Reserve for Unpaid Losses and Loss Adjustment Expenses - GB Additional information (Details) - Group Benefits - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2023	Mar. 31, 2022
Liability for Claims and Claims Adjustment Expense [Line Items]
Prior incurral year development [1]	$ (133)	$ (119)
Disability Insurance Policy [Member]
Liability for Claims and Claims Adjustment Expense [Line Items]
Prior incurral year development [1]	120	80
group life term, disability and accident [Member]
Liability for Claims and Claims Adjustment Expense [Line Items]
Prior incurral year development [1]	8	$ 35
Supplemental Health
Liability for Claims and Claims Adjustment Expense [Line Items]
Prior incurral year development [1]	$ 5