XML 92 R81.htm IDEA: XBRL DOCUMENT v3.24.0.1

Statutory Accounting and Regulatory Requirements - Additional Information (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2024
Dividends to the Company	10.00%
Dividends paid	$ 56.0	$ 77.7	$ 148.4
Forecast [Member]
Dividends permissible to pay without seeking regulatory approval				$ 52.6

X

- Definition

Statutory Accounting Practices Future Dividend Payments Percentage

+ References

No definition available.

+ Details

Name:	amsf_StatutoryAccountingPracticesFutureDividendPaymentsPercentage
Namespace Prefix:	amsf_
Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	duration

X

- Definition

Cash outflow in the form of capital distributions and dividends to common shareholders, preferred shareholders and noncontrolling interests.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 15
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482740/230-10-45-15

+ Details

Name:	us-gaap_PaymentsOfDividends
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

X

- Definition

Amount of dividends available for payment after computation of statutory restrictions on capital surplus.

+ References

No definition available.

+ Details

Name:	us-gaap_StatutoryAccountingPracticesStatutoryAmountAvailableForDividendPayments
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

X

- Details

Name:	srt_StatementScenarioAxis=srt_ScenarioForecastMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: