Medical Claims and Related Payables - Narrative (Details) - USD ($) $ in Millions	Mar. 31, 2026	Dec. 31, 2025
Insurance [Abstract]
Related payables associated with retained liability	$ 39.8	$ 34.5

Liability For Claims And Claims Adjustment Expense, Amounts Recoverable under risk sharing arrangements

No definition available.

Name:	agl_LiabilityForClaimsAndClaimsAdjustmentExpenseAmountsRecoverable
Namespace Prefix:	agl_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant