Fair Value, Reconciliations of Assets and Liabilities Measured at Fair Value on Recurring Basis Using Significant Unobservable Inputs (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Fixed Maturities Available-for-Sale [Member]
Reconciliations for All Assets and Liabilities [Roll Forward]
Beginning balance	$ 693	$ 437	$ 633	$ 419
Net realized investment gains (losses) and net change in unrealized investment gains (losses), included in net income	0	0	0	0
Net realized investment gains (losses) and net change in unrealized investment gains (losses), included in OCI	77	16	32	27
Purchases	39	76	151	152
Sales	(9)	0	(9)	0
Settlements	(9)	(6)	(15)	(12)
Transfers into Level 3	0	40	0	45
Transfers out of Level 3	(14)	(32)	(15)	(100)
Ending balance	777	531	777	531
Unrealized gains (losses) recognized in net income (loss) on level 3 assets and liabilities	0	0	0	0
Unrealized gains (losses) recognized in other comprehensive income (loss) on level 3 assets and liabilities	76	15	34	25
Corporate Bonds and Other [Member]
Reconciliations for All Assets and Liabilities [Roll Forward]
Beginning balance	496	253	468	222
Net realized investment gains (losses) and net change in unrealized investment gains (losses), included in OCI	59	12	22	20
Purchases	4	76	71	132
Settlements	(4)	(2)	(6)	(4)
Transfers out of Level 3		(1)		(32)
Ending balance	555	338	555	338
Unrealized gains (losses) recognized in other comprehensive income (loss) on level 3 assets and liabilities	58	10	24	17
Asset-Backed [Member]
Reconciliations for All Assets and Liabilities [Roll Forward]
Beginning balance	197	184	165	197
Net realized investment gains (losses) and net change in unrealized investment gains (losses), included in OCI	18	4	10	7
Purchases	35		80	20
Sales	(9)		(9)
Settlements	(5)	(4)	(9)	(8)
Transfers into Level 3		40		45
Transfers out of Level 3	(14)	(31)	(15)	(68)
Ending balance	222	193	222	193
Unrealized gains (losses) recognized in other comprehensive income (loss) on level 3 assets and liabilities	18	5	10	8
Fixed Maturities Trading [Member]
Reconciliations for All Assets and Liabilities [Roll Forward]
Beginning balance	3	5	4	6
Net realized investment gains (losses) and net change in unrealized investment gains (losses), included in net income	1	(1)		(2)
Ending balance	4	4	4	4
Unrealized gains (losses) recognized in net income (loss) on level 3 assets and liabilities	1	(1)		(2)
Total Fixed Maturities [Member]
Reconciliations for All Assets and Liabilities [Roll Forward]
Beginning balance	696	442	637	425
Net realized investment gains (losses) and net change in unrealized investment gains (losses), included in net income	1	(1)	0	(2)
Net realized investment gains (losses) and net change in unrealized investment gains (losses), included in OCI	77	16	32	27
Purchases	39	76	151	152
Sales	(9)	0	(9)	0
Settlements	(9)	(6)	(15)	(12)
Transfers into Level 3	0	40	0	45
Transfers out of Level 3	(14)	(32)	(15)	(100)
Ending balance	781	535	781	535
Unrealized gains (losses) recognized in net income (loss) on level 3 assets and liabilities	1	(1)	0	(2)
Unrealized gains (losses) recognized in other comprehensive income (loss) on level 3 assets and liabilities	76	15	34	25
Equity Securities [Member]
Reconciliations for All Assets and Liabilities [Roll Forward]
Beginning balance	16	21	19	19
Net realized investment gains (losses) and net change in unrealized investment gains (losses), included in net income	(4)		(7)	2
Purchases		2		2
Transfers into Level 3	15		15
Ending balance	27	$ 23	27	23
Unrealized gains (losses) recognized in net income (loss) on level 3 assets and liabilities	$ (4)		$ (7)	$ 3