Other Compensation Liabilities - Narrative (Details) - USD ($) $ in Millions	12 Months Ended
Dec. 31, 2025	Dec. 31, 2024	Dec. 31, 2023
Share-Based Payment Arrangement [Abstract]
Profit interests compensation expense	$ 38.0	$ 19.0	$ 0.0
Redemption of profit sharing interests for cash	$ 2.7	$ 0.3	$ 0.0

The amount of profit interests compensation expense (income).

No definition available.

Name:	aami_DeferredCompensationLiabilityProfitInterestsExpenseIncome
Namespace Prefix:	aami_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration