Document And Entity Information
Note To Financial Statement Details Textual
statementsignificantaccountingpoliciespolicies
us-gaap_AssetsFairValueDisclosure
Estimated Fair Value
statementnote5fairvaluemeasurementstables
statementnote6debtandequitysecuritiestables
statementnote7loansreceivableandcreditdisclosurestables
Goodwill and Intangible Assets, Goodwill, Policy [Policy Text Block]
statementnote8otherrealestateownedtables
statementnote10coredepositintangibleassettables
us-gaap_AssetsHeldForSaleLongLivedFairValueDisclosure
Other real estate owned
us-gaap_DisclosureTextBlockAbstract
Notes to Financial Statements
statementnote11securedborrowingstables
statementnote12regulatorymatterstables
statementnote5assetsmeasuredatfairvalueonarecurringbasisdetails
statementnote5assetsmeasuredatfairvalueonanonrecurringbasisdetails
statementnote5fairvaluequantitativeinformationdetails
statementnote5estimatedfairvaluesoffinancialinstrumentsdetails
(Decrease) in securities sold under agreements to repurchase and federal funds purchased
statementnote6securitiesavailableforsaledetails
statementnote6proceedsgainsandlossesfromsecuritiesavailableforsaledetails
statementnote7activityinallowanceforloanlossesdetails
statementnote6securitiesavailableforsalecontinuousunrealizedlosspositiondetails
statementnote7loansreceivableimpairmentanalysisdetails
statementnote7allowanceforloanlossesimpairmentanalysisdetails
statementnote7averagerecordedinvestmentandinterestincomerecognizedonimpairedloansdetails
statementnote7impairedloansdetails
us-gaap_LoansHeldForSaleFairValueDisclosure
Loans held for sale
Noninterest expense:
statementnote7pastdueloansdetails
statementnote7troubleddebtrestructuringsdetails
statementnote7creditriskprofilebasedonpaymentactivitydetails
statementnote7creditriskprofilebyinternallyassignedgradedetails
statementnote10coredepositintangibleassetsdetails
statementnote8componentsofotherrealestateowneddetails
us-gaap_CashAndCashEquivalentsFairValueDisclosure
Cash and due from banks
statementnote10estimatedremainingamortizationexpenseoncoredepositsdetails
statementnote10coredepositintangibleassetsactivitydetails
statementnote12actualcapitalamountsandratiosdetails
statementnote11pledgedcollateralatestimatedfairvaluedetails
us-gaap_DeferredTaxAssetsNet
Deferred income taxes
Notes To Financial Statements
Notes To Financial Statements [Abstract]
Increase (decrease) in deposits
Data processing
Mortgage-backed Securities, Issued by US Government Sponsored Enterprises [Member]
CASH FLOWS FROM FINANCING ACTIVITIES
us-gaap_NetCashProvidedByUsedInInvestingActivities
Net cash (used in) investing activities
Professional fees
us-gaap_SecurityOwnedAndPledgedAsCollateralFairValue
Securities sold under agreements to repurchase
Occupancy expenses, net
Dividends declared per share (in dollars per share)
Cash dividends declared, per share (in dollars per share)
US Government Agencies Debt Securities [Member]
US Treasury Securities [Member]
Real Estate [Domain]
Maturity Overnight [Member]
Real Estate, Type of Property [Axis]
Maturity Greater than 90 Days [Member]
Measurement Frequency [Axis]
Core deposit intangible amortization
Amortization of core deposit intangible asset
Amortization
Fair Value, Measurement Frequency [Domain]
Repurchase Agreements and Similar Transactions, Maturity Periods [Domain]
Repurchase Agreements and Similar Transactions, Maturity Periods [Axis]
Fair Value, Measurements, Recurring [Member]
Other borrowings
Fair Value, Measurements, Nonrecurring [Member]
us-gaap_OtherDepreciationAndAmortization
Amortization, net
Statement [Table]
us-gaap_GoodwillImpairmentLoss
Goodwill, Impairment Loss
us-gaap_ImpairmentOfRealEstate
Impairment of other real estate owned
Income Statement [Abstract]
Collateral Related to Term Repurchase Agreements [Member]
Information related to term repurchase agreements of collateral.
Collateral Related to Securities Sold Under Agreements to Repurchase [Member]
Information related to securities sold under an agreement to repurchase.
us-gaap_ImpairedFinancingReceivableInterestIncomeAccrualMethod
Impaired financing receivable, interest income, accrual method
us-gaap_ImpairedFinancingReceivableRelatedAllowance
Impaired financing receivable, related allowance
us-gaap_ImpairedFinancingReceivableWithRelatedAllowanceRecordedInvestment
Impaired financing receivable with related allowance
us-gaap_ImpairedFinancingReceivableWithNoRelatedAllowanceRecordedInvestment
Impaired financing receivable with no related allowance
us-gaap_GainLossOnSaleOfPropertyPlantEquipment
Loss on sale of premises and equipment, net
us-gaap_GainsLossesOnSalesOfOtherRealEstate
(Gain) loss on sale of other real estate owned, net
us-gaap_ImpairedFinancingReceivableAverageRecordedInvestment
Impaired financing receivable, average recorded investment
us-gaap_ImpairedFinancingReceivableWithRelatedAllowanceInterestIncomeAccrualMethod
Impaired financing receivable, with related allowance, interest income, accrual method
us-gaap_ImpairedFinancingReceivableWithNoRelatedAllowanceInterestIncomeAccrualMethod
Impaired financing receivable, with no related allowance, interest income, accrual method
us-gaap_ImpairedFinancingReceivableRecordedInvestment
Impaired financing receivable, recorded investment
us-gaap_WeightedAverageNumberDilutedSharesOutstandingAdjustment
Weighted Average Number Diluted Shares Outstanding Adjustment
us-gaap_ImpairedFinancingReceivableWithNoRelatedAllowanceUnpaidPrincipalBalance
Impaired financing receivable with no related allowance, unpaid principal balance
us-gaap_WeightedAverageNumberOfShareOutstandingBasicAndDiluted
Weighted Average Number of Shares Outstanding, Basic and Diluted
Salaries and employee benefits
us-gaap_ImpairedFinancingReceivableWithRelatedAllowanceUnpaidPrincipalBalance
Impaired financing receivable with related allowance, unpaid principal balance
Weighted Average [Member]
Maximum [Member]
us-gaap_ImpairedFinancingReceivableWithNoRelatedAllowanceAverageRecordedInvestment
Impaired financing receivable, with no related allowance, average recorded investment
Minimum [Member]
us-gaap_ImpairedFinancingReceivableWithRelatedAllowanceAverageRecordedInvestment
Impaired financing receivable, with related allowance, average recorded investment
Range [Axis]
us-gaap_ImpairedFinancingReceivableUnpaidPrincipalBalance
Impaired financing receivable, unpaid principal balance
Range [Domain]
Basic and diluted earnings per share (in dollars per share)
us-gaap_RepaymentsOfLongTermDebt
Payments on FHLB borrowings and other borrowings
Fair Value, Inputs, Level 3 [Member]
Fair Value, Inputs, Level 2 [Member]
Business development
Commercial Real Estate Portfolio Segment [Member]
Securities gains, net
Securities gains, net
Fair Value, Hierarchy [Axis]
Fair Value Hierarchy [Domain]
Financing Receivable Portfolio Segment [Axis]
Fair Value, Inputs, Level 1 [Member]
Financing Receivable Portfolio Segment [Domain]
Commercial Portfolio Segment [Member]
Federal funds purchased
us-gaap_Deposits
Total deposits
Securities sold under agreements to repurchase
Realized Gain (Loss) on Investments [Table Text Block]
Gain on sale of loans held for sale
Schedule of Unrealized Loss on Investments [Table Text Block]
Valuation Technique [Axis]
Proceeds from short-term FHLB borrowings, net
Valuation Technique [Domain]
Fair Value Inputs, Assets, Quantitative Information [Table Text Block]
us-gaap_DepositsFairValueDisclosure
Deposits
Savings and money market
Amount of interest bearing deposits with no stated maturity, which may include passbook and statement savings accounts and money-market deposit accounts (MMDAs), combined with the amount of deposits in accounts that offer many of the same services as checking accounts although transactions may be somewhat more limited, share some of the characteristics of a money market fund and are insured by the Federal government, also known as money market accounts.
Interest bearing deposits and federal funds sold
Interest income derived from funds deposited with both domestic and foreign financial institutions including funds in money market and other accounts. And, interest income on federal funds sold. Federal funds sold represent the excess federal funds held by one commercial bank which it lends to another commercial bank, usually at an agreed-upon (federal funds) rate of interest. Such loans are made for legal reserve requirement purposes of the borrowing bank and generally are of short-duration (overnight).
Other real estate owned expense, net
The net gain (loss) resulting from sales and other disposals of other real estate owned, increases (decreases) in the valuation allowance for foreclosed real estate, write-downs of other real estate owned after acquisition or physical possession and expenses and income in connection with holding other real estate owned.
Merchant and card fees
Fee income from merchant card transactions and ATM operations.
us-gaap_DividendPayableDateToBePaidDayMonthAndYear
Dividends Payable, Date to be Paid
us-gaap_DividendsPayableDateDeclaredDayMonthAndYear
Dividends Payable, Date Declared
us-gaap_DividendsPayableDateOfRecordDayMonthAndYear
Dividends Payable, Date of Record
Dividend payable
Amortized cost
us-gaap_AvailableForSaleSecuritiesAccumulatedGrossUnrealizedLossBeforeTax
Gross unrealized losses
Gross unrealized gains
Finite-lived Intangible Assets Amortization Expense [Table Text Block]
NOW accounts
Schedule of Available-for-sale Securities Reconciliation [Table Text Block]
us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesMinorityInterestAndIncomeLossFromEquityMethodInvestments
Income before income taxes
Demand, noninterest bearing
us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionLessThan12MonthsAccumulatedLoss
Less than 12 months, unrealized losses
us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionAccumulatedLoss
Total unrealized losses
Wealth management income
Fair Value Measurements, Nonrecurring [Table Text Block]
us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPosition12MonthsOrLongerAccumulatedLoss
12 months or more, unrealized losses
Fair Value, Assets Measured on Recurring Basis [Table Text Block]
Provision for income taxes
Class of Stock [Axis]
Impaired Financing Receivables [Table Text Block]
Troubled Debt Restructurings on Financing Receivables [Table Text Block]
Decrease in federal funds sold
us-gaap_FinancingReceivablesImpairedTroubledDebtRestructuringWriteDown
Financing Receivables, Impaired, Troubled Debt Restructuring, Write-down
us-gaap_FinancingReceivableModificationsRecordedInvestment
Financing Receivable, Modifications, Recorded Investment
us-gaap_FinancingReceivableModificationsPreModificationRecordedInvestment2
Financing receivable modifications, pre-modification outstanding, recorded investment
us-gaap_FinancingReceivableModificationsPostModificationRecordedInvestment2
Financing receivable modifications, post modification outstanding, recorded investment
us-gaap_FinancingReceivableModificationsNumberOfContracts2
Financing receivable modifications, number of contracts
New Accounting Pronouncements, Policy [Policy Text Block]
us-gaap_FinancingReceivableModificationsSubsequentDefaultNumberOfContracts1
Financing Receivable, Modifications, Subsequent Default, Number of Contracts
us-gaap_FinancingReceivableCollectivelyEvaluatedForImpairment
Collectively evaluated for impairment
us-gaap_FinancingReceivableIndividuallyEvaluatedForImpairment
Individually evaluated for impairment
Consolidation, Policy [Policy Text Block]
Service fees
us-gaap_AllowanceForLoanAndLeaseLossRecoveryOfBadDebts
Recoveries of loans charged-off
Financing Receivables, Equal to Greater than 90 Days Past Due [Member]
us-gaap_FinancingReceivableRecordedInvestmentPastDue
Financing receivable, recorded investment, past due
CASH FLOWS FROM INVESTING ACTIVITIES
Past Due Financing Receivables [Table Text Block]
us-gaap_NetCashProvidedByUsedInOperatingActivities
Net cash provided by operating activities
Financing Receivables [Text Block]
Financing Receivables, Period Past Due [Axis]
Financing Receivables, Period Past Due [Domain]
Nonperforming Financial Instruments [Member]
Performing Financial Instruments [Member]
Scenario, Unspecified [Domain]
us-gaap_FinancingReceivableAllowanceForCreditLossesCollectivelyEvaluatedForImpairment
Collectively evaluated for impairment
Scenario [Axis]
us-gaap_FinancingReceivableAllowanceForCreditLossesIndividuallyEvaluatedForImpairment1
Individually evaluated for impairment
us-gaap_FinancingReceivableRecordedInvestment90DaysPastDueAndStillAccruing
Financing receivable, recorded investment, 90 days past due and still accruing
us-gaap_FinancingReceivableRecordedInvestmentCurrent
Financing receivable, recorded investment, current
Allowance for Credit Losses on Financing Receivables [Table Text Block]
Financial Instrument Performance Status [Domain]
Financial Instrument Performance Status [Axis]
Financing Receivable Credit Quality Indicators [Table Text Block]
Pass [Member]
Bank premises and equipment, net
Goodwill
Goodwill Disclosure [Text Block]
Time, $250,000 and over
us-gaap_AllowanceForLoanAndLeaseLossesWriteOffs
Loans charged-off
Net proceeds from the sale of other real estate owned
Net income
Net income
Net income
Proceeds from maturities and calls of securities available-for-sale
Proceeds from sale of securities available-for-sale
Other time
Amount of time deposit liabilities, including certificates of deposit, in denominations of less than FDIC insurance limit.
Schedule of Financial Instruments Owned and Pledged as Collateral [Table Text Block]
Financial Instruments Owned and Pledged as Collateral by Type [Axis]
Financial Instruments Owned and Pledged as Collateral, Type [Domain]
us-gaap_Assets
Total assets
LIABILITIES
us-gaap_PaymentsToAcquireAvailableForSaleSecurities
Purchase of securities available-for-sale
Asset Class [Domain]
us-gaap_PaymentsToAcquirePropertyPlantAndEquipment
Purchase of bank premises and equipment, net
Asset Class [Axis]
Other assets
atlo_NetRealizedGainsOnSecuritiesAvailableForSaleTaxProvision
Tax provision applicable to net realized gains on securities available-for-sale
Element defines tax provision made during the period for realized gains on securities available for sale.
atlo_FairValueInputsEstimationOfValue
Unobservable Inputs, Rate
Percentage of estimation of value used as an input to measure fair value.
Internal Credit Assessment [Axis]
us-gaap_FiniteLivedIntangibleAssetsGross
Core deposit intangible asset
Earnings Per Share [Text Block]
Internal Credit Assessment [Domain]
atlo_InterestBearingDepositsFairValueDisclosure
Interest bearing deposits
The fair value disclosure of interest bearing deposits.
Impaired Loan [Member]
A loan which is considered impaired.
Other Real Estate Owned [Member]
Real estate not separately disclosed, including, but not limited to, real estate investments, real estate loans that qualify as investments in real estate, and premises that are no longer used in operations may also be included in real estate owned. This does not include real estate assets taken in settlement of troubled loans through surrender or foreclosure.
Core deposit intangible, net
Beginning core deposit intangible, net
Ending core deposit intangible, net
Evaluation of Collateral [Member]
The type or description of the valuation technique use to determine the value of particular loans or assets.
Appraisal Valuation [Member]
The type or description of the valuation technique being used.
us-gaap_FiniteLivedIntangibleAssetsAccumulatedAmortization
Core deposit intangible asset
us-gaap_InterestAndDividendIncomeOperating
Total interest income
us-gaap_LoansAndLeasesReceivableImpairedInterestLostOnNonaccrualLoans
Loans and Leases Receivable, Impaired, Interest Lost on Nonaccrual Loans
Amendment Flag
us-gaap_FinancingReceivableAllowanceForCreditLosses
Balance
SUPPLEMENTAL DISCLOSURE OF NONCASH INVESTING ACTIVITIES
Interest expense:
Other real estate owned
Other real estate
Change in assets and liabilities:
Document Fiscal Year Focus
Document Fiscal Period Focus
Document Period End Date
us-gaap_TierOneLeverageCapitalRequiredToBeWellCapitalizedToAverageAssets
Tier one leverage capital required to be well capitalized to average assets
us-gaap_InterestExpenseDeposits
Deposits
us-gaap_TierOneLeverageCapitalRequiredForCapitalAdequacyToAverageAssets
Tier one leverage capital required for capital adequacy to risk weighted assets
Loans receivable, net
Current Fiscal Year End Date
Unrealized holding gains (losses) arising during the period
us-gaap_LongTermDebtFairValue
Other borrowings
us-gaap_LoansAndLeasesReceivableAllowance
Balance
Balance
Less: reclassification adjustment for gains realized in net income
Document Information [Line Items]
us-gaap_DividendsCommonStockCash
Cash dividends declared
Document Information [Table]
Entity Current Reporting Status
Entity Voluntary Filers
Entity Filer Category
Document Type
us-gaap_IncreaseDecreaseInLoansHeldForSale
(Increase) decrease in loans held for sale
us-gaap_RealEstateOwnedValuationAllowance
Real Estate Owned, Valuation Allowance
Real Estate Owned [Text Block]
Other borrowed funds
Common stock, shares outstanding (in shares)
Transfer of loans receivable to other real estate owned
us-gaap_InterestExpense
Total interest expense
Substandard [Member]
Other comprehensive income (loss), before tax:
us-gaap_StockholdersEquity
Balance
Balance
Total stockholders' equity
Special Mention [Member]
Entity Well-known Seasoned Issuer
us-gaap_ComprehensiveIncomeNetOfTax
Comprehensive income (loss)
Interest income:
Statement of Financial Position [Abstract]
Regulatory Capital Requirements under Banking Regulations [Text Block]
Reported Value Measurement [Member]
Loans, including fees
Statement of Comprehensive Income [Abstract]
us-gaap_TableTextBlock
Notes Tables
Securities:
us-gaap_TierOneLeverageCapitalToAverageAssets
Tier one leverage capital to average assets
us-gaap_AcquiredFiniteLivedIntangibleAssetsWeightedAverageUsefulLife
Acquired Finite-lived Intangible Assets, Weighted Average Useful Life
Taxable
us-gaap_CapitalRequiredToBeWellCapitalizedToRiskWeightedAssets
Capital required to be well capitalized to risk weighted assets
us-gaap_CapitalToRiskWeightedAssets
Capital to risk weighted assets
us-gaap_LoansAndLeasesReceivableGrossCarryingAmount
Balance
us-gaap_CapitalRequiredForCapitalAdequacyToRiskWeightedAssets
Capital required for capital adequacy to risk weighted assets
Tax-exempt
us-gaap_TierOneRiskBasedCapitalRequiredForCapitalAdequacyToRiskWeightedAssets
Tier one risk based capital required for capital adequacy to risk weighted assets
us-gaap_OtherComprehensiveIncomeLossBeforeTaxPortionAttributableToParent
Other comprehensive income (loss), before tax
us-gaap_TierOneRiskBasedCapitalRequiredToBeWellCapitalizedToRiskWeightedAssets
Tier one risk based capital required to be well capitalized to risk weighted assets
us-gaap_OtherComprehensiveIncomeLossTaxPortionAttributableToParent1
Tax effect related to other comprehensive income (loss)
us-gaap_TierOneRiskBasedCapitalToRiskWeightedAssets
Tier one risk based capital to risk weighted assets
us-gaap_CapitalRequiredToBeWellCapitalized
Capital required to be well capitalized
us-gaap_IncreaseDecreaseInInterestAndDividendsReceivable
Decrease in accrued income receivable
us-gaap_Capital
Capital
us-gaap_CapitalRequiredForCapitalAdequacy
Capital required for capital adequacy
Statement of Stockholders' Equity [Abstract]
us-gaap_TierOneLeverageCapitalRequiredToBeWellCapitalized
Tier one leverage capital required to be well capitalized
us-gaap_TierOneLeverageCapitalRequiredForCapitalAdequacy
Tier one leverage capital required for capital adequacy
us-gaap_TierOneLeverageCapital
Tier one leverage capital
SUPPLEMENTAL DISCLOSURE OF CASH FLOW INFORMATION
us-gaap_OtherComprehensiveIncomeLossNetOfTaxPortionAttributableToParent
Other comprehensive income (loss), net of tax
Other comprehensive income (loss)
us-gaap_TierOneRiskBasedCapitalRequiredToBeWellCapitalized
Tier one risk based capital required to be well capitalized
us-gaap_TierOneRiskBasedCapitalRequiredForCapitalAdequacy
Tier one risk based capital required for capital adequacy
us-gaap_TierOneRiskBasedCapital
Tier one risk based capital
Statement of Cash Flows [Abstract]
Schedule of Compliance with Regulatory Capital Requirements under Banking Regulations [Table Text Block]
us-gaap_IncreaseDecreaseInOtherOperatingAssets
(Increase) decrease in other assets
Accumulated other comprehensive income - net unrealized gain on securities available-for-sale
Securities available-for-sale
Estimated fair value
Available for sale securities
Retained earnings
us-gaap_LiabilitiesAndStockholdersEquity
Total liabilities and stockholders' equity
Federal Home Loan Bank (FHLB) advances
Legal Entity [Axis]
Entity Registrant Name
Entity Central Index Key
Entity [Domain]
Entity Common Stock, Shares Outstanding (in shares)
Accrued income receivable
Accrued income receivable
Loans held for sale
Cash and due from banks
us-gaap_CashAndCashEquivalentsAtCarryingValue
Beginning
Ending
Trading Symbol
Interest bearing deposits in financial institutions
us-gaap_IncreaseDecreaseInAccountsPayableAndAccruedLiabilities
Increase in accrued expenses and other liabilities
us-gaap_InterestIncomeExpenseNet
Net interest income
Common Stock [Member]
Equity Component [Domain]
Equity Components [Axis]
Noninterest income:
us-gaap_CashAndCashEquivalentsPeriodIncreaseDecrease
Net increase (decrease) in cash and due from banks
us-gaap_AvailableForSaleSecuritiesGrossRealizedLosses
Gross realized losses on securities available-for-sale
us-gaap_InterestIncomeExpenseAfterProvisionForLoanLoss
Net interest income after provision for loan losses
us-gaap_AvailableForSaleSecuritiesGrossRealizedGains
Gross realized gains on securities available-for-sale
Provision for loan losses
Provision (credit) for loan losses
Additional Paid-in Capital [Member]
us-gaap_ProvisionForLoanLossesExpensed
Provision for loan losses
Retained Earnings [Member]
Common stock, par value (in dollars per share)
us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionLessThanTwelveMonthsFairValue
Less than 12 months, estimated fair value
Schedule of Accounts, Notes, Loans and Financing Receivable [Table Text Block]
us-gaap_NoninterestIncome
Total noninterest income
us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionTwelveMonthsOrLongerFairValue
12 months or more, estimated fair value
us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionFairValue
Total estimated fair value
Other noninterest income
US Treasury and Government [Member]
Investments in Debt and Marketable Equity Securities (and Certain Trading Assets) Disclosure [Text Block]
Major Types of Debt and Equity Securities [Domain]
Major Types of Debt and Equity Securities [Axis]
Allowance for Loan Losses Disaggregated on Basis of Impairment Analysis Method [Table Text Block]
Tabular disclosure of credit losses for current financing receivables on basis of impairment analysis method (such as trade and accounts receivable), including a roll forward of the balance. An alternative caption includes allowance for doubtful accounts.
Common stock, $2 par value, authorized 18,000,000 shares; issued and outstanding 9,310,913 shares as of June 30, 2016 and December 31, 2015
AOCI Attributable to Parent [Member]
atlo_ProvisionForOffBalanceSheetCommitments
Provision for off-balance sheet commitments
Amount of expense related to off-balance sheet commitments.
Significant Accounting Policies [Text Block]
Common stock, shares issued (in shares)
Corporate Debt Securities [Member]
Net (increase) in loans
The net change during the reporting period in the value of loans or securitized loans that are held in portfolio.
Common stock, shares authorized (in shares)
US States and Political Subdivisions Debt Securities [Member]
atlo_NetIncreaseDecreaseInInterestBearingDepositsInFinancialInstitutions
Net (increase) decrease in interest bearing deposits in financial institutions
The net cash inflow or outflow associated with interest bearing deposits in financial institutions.
Accounting Policies [Abstract]
us-gaap_PaymentsOfDividends
Dividends paid
Statement [Line Items]
Subsequent Events [Text Block]
us-gaap_PolicyTextBlockAbstract
Accounting Policies
CASH FLOWS FROM OPERATING ACTIVITIES
Core Deposits [Member]
us-gaap_AvailableForSaleSecuritiesGrossRealizedGainsLossesSaleProceeds
Proceeds from sales of securities available-for-sale
Fair Value Disclosures [Text Block]
Dividends Disclosure [Text Block]
Disclosure of all or some of the information related to dividends declared, but not paid, as of the financial reporting date.
Finite-Lived Intangible Assets by Major Class [Axis]
Finite-Lived Intangible Assets, Major Class Name [Domain]
Watch [Member]
A category of financing receivables considered to be on watch status.
Fair Value, by Balance Sheet Grouping [Table Text Block]
Loans and Leases Receivable Commitments [Text Block]
Reflects the amount of cash required to fully fund agreements to provide advances to borrowers and lessees at fixed and variable interest rates depending on certain facts or circumstances.
us-gaap_AvailableForSaleSecuritiesGrossUnrealizedLoss
Available-for-sale Securities, Gross Unrealized Loss
us-gaap_LoansReceivableFairValueDisclosure
Loans receivable
us-gaap_NetCashProvidedByUsedInFinancingActivities
Net cash provided by (used in) financing activities
Equity Securities, Other [Member]
Ownership interest or right to acquire or dispose of ownership interest in corporations and other legal entities for which ownership interest is represented by shares other than financial industry common stock.
us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseRemainderOfFiscalYear
2016
Construction and Land Development [Member]
Property classified as construction and land development.
atlo_FinitelivedIntangibleAssetsAmortizationExpenseAfterYearSix
After
The amount of amortization expense relating to finite lived intangible assets after year six.
Estimate of Fair Value Measurement [Member]
atlo_CommonEquityTierOneCapitalConservationBuffer
Common Equity Tier One Capital Conservation Buffer
A capital conservation buffer, comprised of Common Equity Tier 1, is established above the regulatory minimum capital requirement.
One to Four Family Residential Real Estate [Member]
Property classified as 1-4 family residential real estate.
Measurement Basis [Axis]
Fair Value Measurement [Domain]
atlo_FiniteTaxLivedIntangibleAssetUsefulLife
Finite Tax Lived Intangible Asset, Useful Life
Useful tax life of finite-lived intangible assets, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.
atlo_FinitelivedIntangibleAssetsAmortizationExpenseYearSix
2021
The amount of amortization expense relating to finite lived intangible assets in year six.
Debt Disclosure [Text Block]
Reliance State Bank [Member]
The entity Reliance State Bank.
Conducts Business Out of Offices at Story City, Garner, and Kleme, Iowa [Member]
Also conducts business out of three offices; Story City, Garner and Kleme, Iowa.
State Bank and Trust [Member]
State Bank is an Iowa, state-chartered, FDIC insured commercial bank. It provides full-service banking to businesses and residents within the Nevada area from its main Nevada location and one office in Colo, Iowa. It has a strong presence in agricultural, commercial and residential real estate lending.
United Bank and Trust [Member]
United Bank is a nationally-chartered, commercial bank insured by the FDIC. It offers a broad range of deposit and loan products, as well as trust services to customers located in the Marshalltown and surrounding Marshall County area.
Effective January 2019 [Member]
Represents regulations effective in January 2019.
Boone Bank and Trust [Member]
Boone Bank is an Iowa, state-chartered, FDIC insured commercial bank. It provides full service banking to businesses and residents within the Boone community and surrounding area. It is actively engaged in agricultural, consumer and commercial lending, including real estate, operating and equipment loans. It conducts business from its main office and a full service office, both located in Boone.
Income taxes
Also Conducts Business Out of 3 Full Service Offices in Des Moines Metro Area [Member]
In addition to First National Bank, also conducts business out of 3 full service offices in the Des Moines metro area.
Interest
First National Bank [Member]
First National is a nationally-chartered, commercial bank insured by the Federal Deposit Insurance Corporation (the "FDIC"). It provides full-service banking to businesses and residents within the Ames community and surrounding area. It provides a variety of products and services designed to meet the needs of the market it serves. First National conducts business out of three full-service offices, all located in the city of Ames and a full-service office in Ankeny, Iowa.
atlo_TroubledDebtRestructuringLoanPaymentDefaultPeriod
Troubled Debt Restructuring, Loan Payment Default Period
Represents troubled debt restructuring loan payment default period.
Adjustments to reconcile net income to net cash provided by operating activities:
atlo_CommonEquityTierOneCapitalRequiredToBeWellCapitalizedToRiskWeightedAssets
Common equity tier one capital required to be well capitalized to risk weighted assets
The Common Equity Tier 1 capital ratio (Tier 1 capital divided by risk weighted assets) required to be categorized as "well capitalized" under the regulatory framework for prompt corrective action.
atlo_CommonEquityTierOneCapitalRequiredToBeWellCapitalized
Common equity tier one capital required to be well capitalized
The amount of Common Equity Tier 1 Risk Based Capital required to be categorized as well capitalized under the regulatory framework for prompt corrective action.
atlo_CommonEquityTierOneRiskBasedCapitalRequiredForCapitalAdequacyToRiskWeightedAssets
Common equity tier one risk based capital required for capital adequacy to risk weighted assets
The minimum Common Equity Tier One Capital Ratio (Tier one capital divided by risk-weighted assets) required for capital adequacy purposes under the regulatory framework for prompt corrective action.
atlo_CommonEquityTierOneCapitalRequiredForCapitalAdequacy
Common equity tier one capital required for capital adequacy
The minimum amount of common equity tier 1 capital required for capital adequacy purposes under the regulatory framework for prompt corrective action.
atlo_CommonEquityTierOneRiskBasedCapitalToRiskWeightedAssets
Common equity tier one risk based capital to risk weighted assets
Common Equity Tier 1 capital divided by risk weighted assets as defined by regulations.
atlo_CommonEquityTierOneRiskBasedCapital
Common equity tier one capital
Common Equity Tier 1 Risk Based Capital as defined in the regulations.
Consumer and Other [Member]
Segment of the company's total financing receivables related to consumer and other receivables.
Agriculture [Member]
Segment of the company's total financing receivables related to agriculture receivables.
Family Residential Real Estate 1-4 [Member]
Segment of the company's total financing receivables related to 1-4 Family residential real estate.
Construction Real Estate [Member]
Segment of the company's total financing receivables related to construction real estate.
Agriculture Real Estate [Member]
Segment of the company's total financing receivables related to agricultural real estate receivables
us-gaap_InterestPayableCurrentAndNoncurrent
Accrued interest payable
Accrued expenses and other liabilities
Financing Receivables 30 to 89 Days Past Due [Member]
Financing receivables that are more than 29 days past due but fewer than 90 days past due.
us-gaap_Depreciation
Depreciation
Average Investment in Impaired Loans and Interest Income Recognized [Table Text Block]
Tabular disclosure of average investment in impaired loans and interest income recognized.
atlo_LoanAndLeaseReceivableConsumerAndResidential
Loan and lease receivable, consumer and residential
Element defines loans and lease receivable pertaining to consumer and residential loans at book value.
Schedule of Finite-Lived Intangible Assets, Future Amortization Expense [Table Text Block]
atlo_LoanAndLeaseReceivableOtherThanConsumerAndResidential
Loan and lease receivable other than consumer and residential
Element defines loans and lease receivable other than consumer and residential loans at book value.
Credit Risk Profile Based on Payment Activity on Disaggregated Basis [Table Text Block]
Tabular disclosure of credit risk profile based on payment activity, on a disaggregated basis.
us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseYearTwo
2017
us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseYearThree
2018
Substandard Impaired [Member]
A category of financing receivables that are inadequately protected by the current sound worth and paying capacity of the obligor or of the collateral pledged, if any. Loans so classified have a well-defined weakness or weaknesses that jeopardize the liquidation of the debt. They are characterized by the distinct possibility that the creditor will sustain some loss if the deficiencies are not corrected. Also impaired.
us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseYearFour
2019
us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseYearFive
2020
Other Real Estate, Roll Forward [Table Text Block]
us-gaap_Liabilities
Total liabilities
us-gaap_FederalHomeLoanBankBorrowingsFairValueDisclosure
FHLB advances
us-gaap_SecuritiesLoanedOrSoldUnderAgreementsToRepurchaseFairValueDisclosure
Securities sold under agreements to repurchase
us-gaap_FederalFundsPurchasedFairValueDisclosure
Federal funds purchased
Deferred income taxes
Intangible Assets Disclosure [Text Block]
Schedule of Finite-Lived Intangible Assets [Table Text Block]
FDIC insurance assessments
us-gaap_NoninterestExpense
Total noninterest expense
Other operating expenses, net
Additional paid-in capital
STOCKHOLDERS' EQUITY
us-gaap_DeferredIncomeTaxExpenseBenefit
Deferred income taxes