Reserves - Narrative (Details) - USD ($) $ in Millions	6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020
Liability for Claims and Claims Adjustment Expense [Line Items]
Favorable (unfavorable) prior year development	$ 34.5	$ 42.8
Global Lifestyle
Liability for Claims and Claims Adjustment Expense [Line Items]
Favorable (unfavorable) prior year development	35.0	29.0
Global Housing
Liability for Claims and Claims Adjustment Expense [Line Items]
Favorable (unfavorable) prior year development	(4.6)	4.3
Corporate and Other
Liability for Claims and Claims Adjustment Expense [Line Items]
Favorable (unfavorable) prior year development	$ 4.1	$ 9.5