Accumulated Other Comprehensive Income Loss - Reclassifications from AOCI (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Accumulated Other Comprehensive Income (Loss) [Line Items]
Income tax expense	$ 124	$ 84	$ 195	$ 229
Interest Expense	57	63	121	127
Net Investment Income	339	488	798	958
Income before income taxes	592	456	936	1,231
Net income	468	372	741	1,002
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	34	32	67	42
Net Unrealized Gain on Securities | Reclassification out of Accumulated Other Comprehensive Income
Accumulated Other Comprehensive Income (Loss) [Line Items]
Net realized capital gains	52	50	105	71
Income tax expense	11	11	22	15
Income before income taxes	52	50	105	71
Net income	41	39	83	56
Accumulated Net Gain (Loss) from Cash Flow Hedges Attributable to Parent | Reclassification out of Accumulated Other Comprehensive Income
Accumulated Other Comprehensive Income (Loss) [Line Items]
Income tax expense	1	1	2	1
Income before income taxes	6	3	10	4
Net income	5	2	8	3
Accumulated Net Gain (Loss) from Cash Flow Hedges Attributable to Parent | Reclassification out of Accumulated Other Comprehensive Income | Interest rate swaps
Accumulated Other Comprehensive Income (Loss) [Line Items]
Net realized capital gains		2		2
Interest Expense	(2)	1	(2)	1
Net Investment Income	7		10
Accumulated Net Gain (Loss) from Cash Flow Hedges Attributable to Parent | Reclassification out of Accumulated Other Comprehensive Income | Currency Swap [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Net Investment Income	1	0	2	1
Amortization of prior service credit | Reclassification out of Accumulated Other Comprehensive Income
Accumulated Other Comprehensive Income (Loss) [Line Items]
Insurance operating costs and other expenses	1	2	3	3
Amortization of actuarial loss | Reclassification out of Accumulated Other Comprehensive Income
Accumulated Other Comprehensive Income (Loss) [Line Items]
Insurance operating costs and other expenses	(16)	(13)	(33)	(25)
Pension and Other Postretirement Plan Adjustments | Reclassification out of Accumulated Other Comprehensive Income
Accumulated Other Comprehensive Income (Loss) [Line Items]
Income tax expense	(3)	(2)	(6)	(5)
Income before income taxes	(15)	(11)	(30)	(22)
Net income	$ (12)	$ (9)	$ (24)	$ (17)