Fair Value (Unobservable Input Reconciliation) (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Consolidated Securitization Entities
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance at January 1,	$ (12)	$ (12)	$ (11)	$ (13)
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	0	0	0	0
Sales	0	0	0	0
Issuances	0	0	0	0
Settlements	0	0	(1)	1
Transfers into Level 3	0	0	0	0
Transfers out of Level 3	0	0	0	0
Balance at March 31,	(12)	(12)	(12)	(12)
Changes in unrealized gains (losses) included in net income (loss) for the instruments still held at end of period	0	0	0	0
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	163	7	207	(76)
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Input Reconciliation [Roll Forward]
Balance at January 1,	(338)	(345)	(411)	(300)
Total realized/unrealized gains (losses) included in net income (loss)	165	(2)	228	(68)
Total realized/unrealized gains (losses) included in AOCI	41	(21)	51	(4)
Purchases	4	4	12	4
Sales	0	0	0	0
Issuances	(1)	(1)	(1)	(1)
Settlements	2	(7)	(9)	(3)
Transfers into Level 3	0	0	0	0
Transfers out of Level 3	(5)	0	(2)	0
Balance at March 31,	(132)	(372)	(132)	(372)
Changes in unrealized gains (losses) included in net income (loss) for the instruments still held at end of period	163	7	207	(76)
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	(4,520)	723	(5,634)	770
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Input Reconciliation [Roll Forward]
Balance at January 1,	(1,939)	278	(544)	430
Total realized/unrealized gains (losses) included in net income (loss)	(4,505)	737	(5,616)	789
Total realized/unrealized gains (losses) included in AOCI	(135)	21	(210)	19
Purchases	0	0	0	0
Sales	0	0	0	0
Issuances	0	0	0	0
Settlements	(225)	(195)	(434)	(397)
Transfers into Level 3	0	0	0	0
Transfers out of Level 3	0	0	0	0
Balance at March 31,	(6,804)	841	(6,804)	841
Changes in unrealized gains (losses) included in net income (loss) for the instruments still held at end of period	(4,520)	723	(5,634)	770
Residential mortgage loans — FVO
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance at January 1,	392	329	314	308
Total realized/unrealized gains (losses) included in net income (loss)	1	(2)	11	20
Total realized/unrealized gains (losses) included in AOCI	0	0	0	0
Purchases	71	45	149	104
Sales	(4)	(23)	(8)	(71)
Issuances	0	0	0	0
Settlements	(11)	(4)	(17)	(16)
Transfers into Level 3	0	0	0	0
Transfers out of Level 3	0	0	0	0
Balance at March 31,	449	345	449	345
Changes in unrealized gains (losses) included in net income (loss) for the instruments still held at end of period	1	(2)	11	20
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	(2)	11	20
Trading Liabilities
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance at January 1,	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	0	(4)	0	(4)
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 at March 31,	0	(4)	0	(4)
Changes in unrealized gains (losses) included in net income (loss) for the instruments still held at end of period	0	0	0	0
Corporate fixed maturity securities
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance at January 1,	12,792	13,729	12,796	13,432
Total realized/unrealized gains (losses) included in net income (loss)	(5)	30	(44)	43
Total realized/unrealized gains (losses) included in AOCI	339	(407)	929	(489)
Purchases	852	607	1,316	1,089
Sales	(306)	(538)	(602)	(698)
Issuances	0	0	0	0
Settlements	0	0	0	0
Transfers into Level 3	490	252	639	364
Transfers out of Level 3	(452)	(153)	(1,324)	(221)
Balance at March 31,	13,710	13,520	13,710	13,520
Changes in unrealized gains (losses) included in net income (loss) for the instruments still held at end of period	(5)	7	(44)	16
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	(5)	7	(44)	16
U.S. government and agency
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance at January 1,	211	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	7	0	18	0
Purchases	105	55	105	55
Sales	0	0	0	0
Issuances	0	0	0	0
Settlements	0	0	0	0
Transfers into Level 3	0	0	200	0
Transfers out of Level 3	0	0	0	0
Balance at March 31,	323	55	323	55
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
Foreign government
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance at January 1,	712	1,384	856	1,311
Total realized/unrealized gains (losses) included in net income (loss)	4	4	8	7
Total realized/unrealized gains (losses) included in AOCI	2	(27)	(3)	(24)
Purchases	65	88	79	145
Sales	(19)	(20)	(23)	(31)
Issuances	0	0	0	0
Settlements	0	0	0	0
Transfers into Level 3	103	10	41	209
Transfers out of Level 3	(491)	(103)	(582)	(281)
Balance at March 31,	376	1,336	376	1,336
Changes in unrealized gains (losses) included in net income (loss) for the instruments still held at end of period	4	4	7	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	4	4	7	7
Structured Securities
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance at January 1,	6,652	7,642	7,116	7,392
Total realized/unrealized gains (losses) included in net income (loss)	30	43	60	64
Total realized/unrealized gains (losses) included in AOCI	5	13	(9)	(28)
Purchases	940	1,218	1,546	2,023
Sales	(478)	(448)	(903)	(883)
Issuances	0	0	0	0
Settlements	0	0	0	0
Transfers into Level 3	12	153	30	177
Transfers out of Level 3	(461)	(1,603)	(1,140)	(1,727)
Balance at March 31,	6,700	7,018	6,700	7,018
Changes in unrealized gains (losses) included in net income (loss) for the instruments still held at end of period	35	30	63	51
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	35	30	63	51
State and political subdivision
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance at January 1,	36	2	46	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	17	55	17	55
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	(2)	(10)	0
Balance at March 31,	53	55	53	55
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 at January 1,	669	338	432	345
Total realized/unrealized gains (losses) included in net income (loss)	0	2	(24)	0
Total realized/unrealized gains (losses) included in AOCI	11	(2)	41	(4)
Purchases	19	42	23	48
Sales	(17)	(20)	(62)	(23)
Issuances	0	0	0	0
Settlements	0	0	0	0
Transfers into Level 3	2	131	457	132
Transfers out of Level 3	(2)	(2)	(185)	(9)
Balance at March 31,	682	489	682	489
Changes in unrealized gains (losses) included in net income (loss) for the instruments still held at end of period	0	0	(26)	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	(26)	0
FVO And Trading Securities
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance at January 1,	249	521	270	567
Total realized/unrealized gains (losses) included in net income (loss)	(3)	(3)	5	(26)
Total realized/unrealized gains (losses) included in AOCI	0	0	0	0
Purchases	11	74	26	98
Sales	(19)	(126)	(26)	(204)
Issuances	0	0	0	0
Settlements	0	0	0	0
Transfers into Level 3	6	52	23	53
Transfers out of Level 3	(13)	(43)	(67)	(13)
Balance at March 31,	231	475	231	475
Changes in unrealized gains (losses) included in net income (loss) for the instruments still held at end of period	(3)	(6)	5	(19)
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)	(6)	5	(19)
Short-term Investments
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance at January 1,	170	1,358	291	336
Total realized/unrealized gains (losses) included in net income (loss)	0	2	0	2
Total realized/unrealized gains (losses) included in AOCI	5	(1)	8	(1)
Purchases	115	1,702	126	1,822
Sales	(6)	(975)	(247)	(60)
Issuances	0	0	0	0
Settlements	0	0	0	0
Transfers into Level 3	2	0	0	0
Transfers out of Level 3	(111)	(277)	(3)	(290)
Balance at March 31,	175	1,809	175	1,809
Changes in unrealized gains (losses) included in net income (loss) for the instruments still held at end of period	0	1	0	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	0	1	0	1
Separate Accounts
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance at January 1,	1,466	2,056	1,704	1,922
Total realized/unrealized gains (losses) included in net income (loss)	33	(30)	62	5
Total realized/unrealized gains (losses) included in AOCI	0	0	0	0
Purchases	209	153	226	310
Sales	(49)	(83)	(234)	(201)
Issuances	(2)	0	2	1
Settlements	5	(1)	(4)	(2)
Transfers into Level 3	2	0	4	0
Transfers out of Level 3	(37)	(170)	(133)	(110)
Balance at March 31,	1,627	1,925	1,627	1,925
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