Note 10 - Deposits - Interest Expense on Deposits (Details) - USD ($)	12 Months Ended
Dec. 31, 2020	Dec. 31, 2019
Interest-bearing checking	$ 1,465,000	$ 3,147,000
Savings and money market	1,769,000	2,870,000
Time deposits	4,587,000	4,184,000
Total deposit interest expense	$ 7,820,828	$ 10,200,626

The aggregate interest expense incurred on the following for deposits in domestic offices: (1) money market deposits and (2) savings deposits.

No definition available.

+ Details

Name:	atlo_InterestExpenseMoneyMarketAccountsAndSavingsDeposits
Namespace Prefix:	atlo_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Aggregate amount of interest expense on all deposits.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 220
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-04.6)
-URI http://asc.fasb.org/extlink&oid=120399700&loc=SL114874048-224260

+ Details

Name:	us-gaap_InterestExpenseDeposits
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Interest expense incurred on the amount of Negotiable Order of Withdrawal (NOW). Interest-bearing transaction account that combines the payable on demand feature of checks and investment feature of savings accounts. A NOW account is functionally an interest paying checking account.

+ References

+ Details

Name:	us-gaap_InterestExpenseNegotiableOrderOfWithdrawalNOWDeposits
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Interest expense incurred on other deposits in domestic offices.

+ References

+ Details

Name:	us-gaap_InterestExpenseOtherDomesticDeposits
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration