Fair Value (Unobservable Input Reconciliation) (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Residential mortgage loans - FVO
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance, beginning of period	$ 276	$ 438	$ 299	$ 520
Total realized/unrealized gains (losses) included in net income (loss)	4	1	6	3
Total realized/unrealized gains (losses) included in AOCI	0	0	0	0
Purchases	0	0	0	0
Sales	(9)	(17)	(25)	(81)
Issuances	0	0	0	0
Settlements	(9)	(17)	(18)	(37)
Transfers into Level 3	0	0	0	0
Transfers out of Level 3	0	0	0	0
Balance, end of period	262	405	262	405
Changes in unrealized gains (losses) included in net income (loss) for the instruments still held at end of period	1	(1)	1	(8)
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Input Reconciliation [Roll Forward]
Changes in unrealized gains (losses) included in net income (loss) for the instruments still held at end of period	1	(1)	1	(8)
Net Derivatives
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Changes in unrealized gains (losses) included in net income (loss) for the instruments still held at end of period	69	(86)	104	(18)
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Input Reconciliation [Roll Forward]
Balance, beginning of period	(69)	(182)	(225)	(132)
Total realized/unrealized gains (losses) included in net income (loss)	75	(106)	125	(94)
Total realized/unrealized gains (losses) included in AOCI	136	(19)	223	(123)
Purchases	4	4	4	4
Sales	0	0	0	0
Issuances	(1)	0	(1)	0
Settlements	(40)	36	(21)	78
Transfers into Level 3	0	0	0	0
Transfers out of Level 3	0	0	0	0
Balance, end of period	105	(267)	105	(267)
Changes in unrealized gains (losses) included in net income (loss) for the instruments still held at end of period	69	(86)	104	(18)
Net Embedded Derivatives
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Changes in unrealized gains (losses) included in net income (loss) for the instruments still held at end of period	(146)	153	46	184
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Input Reconciliation [Roll Forward]
Balance, beginning of period	(605)	(328)	(739)	(274)
Total realized/unrealized gains (losses) included in net income (loss)	(146)	152	47	188
Total realized/unrealized gains (losses) included in AOCI	(15)	13	(8)	(3)
Purchases	0	0	0	0
Sales	0	0	0	0
Issuances	0	0	0	0
Settlements	(69)	(77)	(135)	(151)
Transfers into Level 3	0	0	0	0
Transfers out of Level 3	0	0	0	0
Balance, end of period	(835)	(240)	(835)	(240)
Changes in unrealized gains (losses) included in net income (loss) for the instruments still held at end of period	(146)	153	46	184
Corporate fixed maturity securities
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance, beginning of period	10,962	10,810	10,467	11,219
Total realized/unrealized gains (losses) included in net income (loss)	0	1	6	9
Total realized/unrealized gains (losses) included in AOCI	226	(369)	595	(433)
Purchases	705	806	1,030	1,321
Sales	(264)	(512)	(351)	(1,221)
Issuances	0	0	0	0
Settlements	0	0	0	0
Transfers into Level 3	104	1	245	140
Transfers out of Level 3	(126)	(116)	(385)	(414)
Balance, end of period	11,607	10,621	11,607	10,621
Changes in unrealized gains (losses) included in net income (loss) for the instruments still held at end of period	(3)	1	(4)	2
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Input Reconciliation [Roll Forward]
Changes in unrealized gains (losses) included in net income (loss) for the instruments still held at end of period	(3)	1	(4)	2
Foreign government
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance, beginning of period	157	179	138	209
Total realized/unrealized gains (losses) included in net income (loss)	0	1	1	2
Total realized/unrealized gains (losses) included in AOCI	(1)	(9)	(2)	(12)
Purchases	2	0	3	1
Sales	(5)	(14)	(6)	(16)
Issuances	0	0	0	0
Settlements	0	0	0	0
Transfers into Level 3	12	0	13	0
Transfers out of Level 3	(22)	(1)	(4)	(28)
Balance, end of period	143	156	143	156
Changes in unrealized gains (losses) included in net income (loss) for the instruments still held at end of period	1	0	1	1
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Input Reconciliation [Roll Forward]
Changes in unrealized gains (losses) included in net income (loss) for the instruments still held at end of period	1	0	1	1
Structured Securities
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance, beginning of period	4,069	4,582	4,266	4,841
Total realized/unrealized gains (losses) included in net income (loss)	12	21	25	43
Total realized/unrealized gains (losses) included in AOCI	41	(12)	62	12
Purchases	401	998	592	1,022
Sales	(205)	(275)	(335)	(539)
Issuances	0	0	0	0
Settlements	0	0	0	0
Transfers into Level 3	6	2	7	51
Transfers out of Level 3	(169)	(639)	(462)	(753)
Balance, end of period	4,155	4,677	4,155	4,677
Changes in unrealized gains (losses) included in net income (loss) for the instruments still held at end of period	11	19	25	39
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Input Reconciliation [Roll Forward]
Changes in unrealized gains (losses) included in net income (loss) for the instruments still held at end of period	11	19	25	39
US States and Political Subdivisions Debt Securities [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance, beginning of period	0	0	0	0
Total realized/unrealized gains (losses) included in net income (loss)	0	0	0	0
Total realized/unrealized gains (losses) included in AOCI	0	0	0	0
Purchases	7	8	7	8
Sales	0	0	0	0
Issuances	0	0	0	0
Settlements	0	0	0	0
Transfers into Level 3	0	0	0	0
Transfers out of Level 3	0	0	0	0
Balance, end of period	7	8	7	8
Changes in unrealized gains (losses) included in net income (loss) for the instruments still held at end of period	0	0	0	0
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Input Reconciliation [Roll Forward]
Changes in unrealized gains (losses) included in net income (loss) for the instruments still held at end of period	0	0	0	0
Equity Securities
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance, beginning of period	434	422	419	428
Total realized/unrealized gains (losses) included in net income (loss)	(2)	(5)	28	(10)
Total realized/unrealized gains (losses) included in AOCI	0	0	0	0
Purchases	41	7	48	5
Sales	(16)	(16)	(38)	(15)
Issuances	0	0	0	0
Settlements	0	0	0	0
Transfers into Level 3	0	0	0	0
Transfers out of Level 3	0	0	0	0
Balance, end of period	457	408	457	408
Changes in unrealized gains (losses) included in net income (loss) for the instruments still held at end of period	(3)	0	15	0
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Input Reconciliation [Roll Forward]
Changes in unrealized gains (losses) included in net income (loss) for the instruments still held at end of period	(3)	0	15	0
Unit-linked and FVO Securities
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance, beginning of period	457	286	405	362
Total realized/unrealized gains (losses) included in net income (loss)	10	(11)	29	(6)
Total realized/unrealized gains (losses) included in AOCI	0	0	0	0
Purchases	38	84	70	104
Sales	(5)	(81)	(7)	(141)
Issuances	0	0	0	0
Settlements	0	0	0	0
Transfers into Level 3	1	0	2	0
Transfers out of Level 3	(7)	(9)	(5)	(50)
Balance, end of period	494	269	494	269
Changes in unrealized gains (losses) included in net income (loss) for the instruments still held at end of period	10	(10)	29	(7)
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Input Reconciliation [Roll Forward]
Changes in unrealized gains (losses) included in net income (loss) for the instruments still held at end of period	10	(10)	29	(7)
Short-term Investments
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance, beginning of period	138	615	33	33
Total realized/unrealized gains (losses) included in net income (loss)	0	0	1	0
Total realized/unrealized gains (losses) included in AOCI	0	(3)	(1)	(3)
Purchases	15	4	119	560
Sales	(25)	(33)	(31)	(11)
Issuances	0	0	0	0
Settlements	0	0	0	0
Transfers into Level 3	2	0	2	0
Transfers out of Level 3	(7)	(24)	0	(20)
Balance, end of period	123	559	123	559
Changes in unrealized gains (losses) included in net income (loss) for the instruments still held at end of period	0	0	1	0
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Input Reconciliation [Roll Forward]
Changes in unrealized gains (losses) included in net income (loss) for the instruments still held at end of period	0	0	1	0
Other Investments
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance, beginning of period	168	0	39	0
Total realized/unrealized gains (losses) included in net income (loss)	0	0	0	0
Total realized/unrealized gains (losses) included in AOCI	0	0	0	0
Purchases	64	0	193	0
Sales	0	0	0	0
Issuances	0	0	0	0
Settlements	0	0	0	0
Transfers into Level 3	0	0	0	0
Transfers out of Level 3	0	0	0	0
Balance, end of period	232	0	232	0
Changes in unrealized gains (losses) included in net income (loss) for the instruments still held at end of period	0	0	0	0
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Input Reconciliation [Roll Forward]
Changes in unrealized gains (losses) included in net income (loss) for the instruments still held at end of period	0	0	0	0
Separate Accounts
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance, beginning of period	897	1,224	937	959
Total realized/unrealized gains (losses) included in net income (loss)	2	(1)	6	1
Total realized/unrealized gains (losses) included in AOCI	0	0	0	0
Purchases	101	270	124	307
Sales	(75)	(323)	(140)	(147)
Issuances	3	(2)	2	(3)
Settlements	(3)	2	(2)	1
Transfers into Level 3	0	71	0	99
Transfers out of Level 3	0	(103)	(2)	(79)
Balance, end of period	925	1,138	925	1,138
Changes in unrealized gains (losses) included in net income (loss) for the instruments still held at end of period	0	0	0	0
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Input Reconciliation [Roll Forward]
Changes in unrealized gains (losses) included in net income (loss) for the instruments still held at end of period	$ 0	$ 0	$ 0	$ 0