XML 56 R50.htm IDEA: XBRL DOCUMENT
v3.24.3

Treasury Stock - Summary of Company's Purchases of Common Stock (Details) - USD ($) $ / shares in Units, $ in Thousands | 1 Months Ended | 3 Months Ended | 9 Months Ended
--- | --- | --- | ---
Aug. 31, 2024 | Jul. 31, 2024 | Sep. 30, 2024 | Sep. 30, 2023 | Sep. 30, 2024 | Sep. 30, 2023
Equity [Abstract] |  |  |  |  |  |  |  |
Total Number of Shares Purchased | 21,586 |  | 0 |  | 21,586 | 0 | 113,411 | 0
Average Price Paid per Share | $ 46.79 | [1] | $ 0 | [1] | $ 46.79 |  | $ 45.16 |
Total Number of Shares Purchased as Part of Publicly Announced Program | 21,586 |  | 0 |  | 21,586 |  |  |
Approximate Dollar Value of Shares that May Yet Be Purchased Under the Program | $ 5,320 |  | $ 6,330 |  | $ 5,320 |  | $ 5,320 |
[1] | Average price paid per share includes commissions and excise tax.

X
- Definition Number of shares purchased as part of publicly announced program. + References No definition available. + Details
Name: | amsf_NumberOfSharesPurchasedAsPartOfPubliclyAnnouncedProgram
Namespace Prefix: | amsf_
Data Type: | xbrli:sharesItemType
Balance Type: | na
Period Type: | duration

X
- References No definition available. + Details
Name: | us-gaap_EquityAbstract
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Amount remaining authorized for purchase of share under share repurchase plan. Includes, but is not limited to, repurchase of stock and unit of ownership. + References No definition available. + Details
Name: | us-gaap_StockRepurchaseProgramRemainingAuthorizedRepurchaseAmount1
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Total cost of shares repurchased divided by the total number of shares repurchased. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Name Accounting Standards Codification -Topic 505 -SubTopic 30 -Section 45 -Paragraph 1 -Publisher FASB -URI https://asc.fasb.org/1943274/2147481549/505-30-45-1 + Details
Name: | us-gaap_TreasuryStockAcquiredAverageCostPerShare
Namespace Prefix: | us-gaap_
Data Type: | dtr-types:perShareItemType
Balance Type: | na
Period Type: | duration

X
- Definition Number of shares that have been repurchased during the period and are being held in treasury. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Name Accounting Standards Codification -Section 50 -Paragraph 2 -SubTopic 10 -Topic 505 -Publisher FASB -URI https://asc.fasb.org/1943274/2147481112/505-10-50-2 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Topic 210 -SubTopic 10 -Name Accounting Standards Codification -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02(29)) -Publisher FASB -URI https://asc.fasb.org/1943274/2147480566/210-10-S99-1 Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef -Topic 505 -SubTopic 10 -Name Accounting Standards Codification -Section S99 -Paragraph 1 -Subparagraph (SX 210.3-04) -Publisher FASB -URI https://asc.fasb.org/1943274/2147480008/505-10-S99-1 + Details
Name: | us-gaap_TreasuryStockSharesAcquired
Namespace Prefix: | us-gaap_
Data Type: | xbrli:sharesItemType
Balance Type: | na
Period Type: | duration