Accumulated Other Comprehensive Income Loss - Reclassifications from AOCI (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Accumulated Other Comprehensive Income (Loss) [Line Items]
Income tax expense	$ 73	$ 118	$ 268	$ 347
Net Investment Income	492	490	1,290	1,448
Interest Expense	58	67	179	194
Income before income taxes	532	653	1,468	1,884
Net income	459	535	1,200	1,537
Reclassification out of Accumulated Other Comprehensive Income
Accumulated Other Comprehensive Income (Loss) [Line Items]
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax	7	51	74	93
Reclassification out of Accumulated Other Comprehensive Income | Net Unrealized Gain on Securities
Accumulated Other Comprehensive Income (Loss) [Line Items]
Net realized capital gains	15	72	120	143
Income tax expense	3	15	25	30
Income before income taxes	15	72	120	143
Net income	12	57	95	113
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 tax expense	2	0	4	1
Income before income taxes	9	2	19	6
Net income	7	2	15	5
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 realized capital gains		0		2
Net Investment Income	9	1	19	1
Interest Expense	(2)	0	(4)	1
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 realized capital gains	1		1
Net Investment Income	1	1	3	2
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	5	5
Reclassification out of Accumulated Other Comprehensive Income | Amortization of actuarial loss
Accumulated Other Comprehensive Income (Loss) [Line Items]
Insurance operating costs and other expenses	(17)	(12)	(50)	(37)
Reclassification out of Accumulated Other Comprehensive Income | Pension and Other Postretirement Plan Adjustments
Accumulated Other Comprehensive Income (Loss) [Line Items]
Income tax expense	(3)	(2)	(9)	(7)
Income before income taxes	(15)	(10)	(45)	(32)
Net income	$ (12)	$ (8)	$ (36)	$ (25)