Consolidated Statements of Operations (unaudited) (Parenthetical) - USD ($) $ in Millions	3 Months Ended
Mar. 31, 2024	Mar. 31, 2023
Income Statement [Abstract]
Net realized losses on investments	$ 8.0	$ 2.5

Investment Impairment Losses included in Net Realized Gains (Losses)

No definition available.

Name:	aiz_InvestmentImpairmentLossesincludedinNetRealizedGainsLosses
Namespace Prefix:	aiz_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration