Accumulated Other Comprehensive Income Loss - Reclassifications from AOCI (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Accumulated Other Comprehensive Income (Loss) [Line Items]
Net Investment Income	$ 509	$ 459
Interest Expense	57	64
Income before income taxes	303	344
Income tax expense	54	71
Net income	249	273
Reclassification out of Accumulated Other Comprehensive Income
Accumulated Other Comprehensive Income (Loss) [Line Items]
Net income	(3)	33
Reclassification out of Accumulated Other Comprehensive Income | Net Unrealized Gain on Securities
Accumulated Other Comprehensive Income (Loss) [Line Items]
Net realized capital gains	4	53
Income before income taxes	4	53
Income tax expense	1	11
Net income	3	42
Reclassification out of Accumulated Other Comprehensive Income | Accumulated Net Gain (Loss) from Cash Flow Hedges Attributable to Parent
Accumulated Other Comprehensive Income (Loss) [Line Items]
Income before income taxes	9	4
Income tax expense	2	1
Net income	7	3
Reclassification out of Accumulated Other Comprehensive Income | Accumulated Net Gain (Loss) from Cash Flow Hedges Attributable to Parent | Interest rate swaps
Accumulated Other Comprehensive Income (Loss) [Line Items]
Net Investment Income	10	3
Interest Expense	(2)
Reclassification out of Accumulated Other Comprehensive Income | Accumulated Net Gain (Loss) from Cash Flow Hedges Attributable to Parent | Currency Swap [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Net Investment Income	1	1
Reclassification out of Accumulated Other Comprehensive Income | Amortization of prior service credit
Accumulated Other Comprehensive Income (Loss) [Line Items]
Insurance operating costs and other expenses	2	2
Reclassification out of Accumulated Other Comprehensive Income | Amortization of actuarial loss
Accumulated Other Comprehensive Income (Loss) [Line Items]
Insurance operating costs and other expenses	(19)	(17)
Reclassification out of Accumulated Other Comprehensive Income | Pension and Other Postretirement Plan Adjustments
Accumulated Other Comprehensive Income (Loss) [Line Items]
Income before income taxes	(17)	(15)
Income tax expense	(4)	(3)
Net income	$ (13)	$ (12)