Fair Value (Unobservable Input Reconciliation) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Residential Mortgage Loans - FVO
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance at January 1,	$ 314	$ 308
Total realized/unrealized gains (losses) included in net income (loss)	8	20	$ 20
Total realized/unrealized gains (losses) included in AOCI	0	0	0
Purchases	297	136
Sales	(11)	(121)
Issuances	0	0
Settlements	(42)	(29)
Transfers into Level 3	0	0
Transfers out of Level 3	0	0
Balance at December 31,	566	314	308
Changes in unrealized gains (losses) included in net income (loss) for the instruments still held at end of period	8	20	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	8	20	20
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	(743)	(234)	(67)
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Input Reconciliation [Roll Forward]
Balance at January 1,	(411)	(300)
Total realized/unrealized gains (losses) included in net income (loss)	(734)	(223)	(83)
Total realized/unrealized gains (losses) included in AOCI	(363)	0	101
Purchases	38	24
Sales	0	0
Issuances	0	0
Settlements	(46)	88
Transfers into Level 3	0	0
Transfers out of Level 3	0	0
Balance at December 31,	(1,516)	(411)	(300)
Changes in unrealized gains (losses) included in net income (loss) for the instruments still held at end of period	(743)	(234)	(67)
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	(2,311)	(176)	(173)
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Input Reconciliation [Roll Forward]
Balance at January 1,	(544)	430
Total realized/unrealized gains (losses) included in net income (loss)	(2,271)	(159)	(173)
Total realized/unrealized gains (losses) included in AOCI	(18)	2	191
Purchases	0	0
Sales	0	0
Issuances	0	0
Settlements	(892)	(817)
Transfers into Level 3	0	0
Transfers out of Level 3	0	0
Balance at December 31,	(3,725)	(544)	430
Changes in unrealized gains (losses) included in net income (loss) for the instruments still held at end of period	(2,311)	(176)	(173)
Corporate fixed maturity securities [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance at January 1,	12,796	13,432
Total realized/unrealized gains (losses) included in net income (loss)	3	69	13
Total realized/unrealized gains (losses) included in AOCI	33	(761)	353
Purchases	3,198	2,556
Sales	(1,295)	(1,425)
Issuances	0	0
Settlements	0	0
Transfers into Level 3	1,089	918
Transfers out of Level 3	(1,897)	(1,993)
Balance at December 31,	13,927	12,796	13,432
Changes in unrealized gains (losses) included in net income (loss) for the instruments still held at end of period	8	24	13
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	8	24	13
Foreign government
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance at January 1,	856	1,311
Total realized/unrealized gains (losses) included in net income (loss)	12	13	61
Total realized/unrealized gains (losses) included in AOCI	(42)	(25)	(110)
Purchases	45	212
Sales	(45)	(45)
Issuances	0	0
Settlements	0	0
Transfers into Level 3	3	7
Transfers out of Level 3	(539)	(617)
Balance at December 31,	290	856	1,311
Changes in unrealized gains (losses) included in net income (loss) for the instruments still held at end of period	12	12	12
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	12	12	12
Structured Securities
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance at January 1,	7,116	7,392
Total realized/unrealized gains (losses) included in net income (loss)	138	124	14
Total realized/unrealized gains (losses) included in AOCI	77	(91)	69
Purchases	2,519	3,167
Sales	(1,815)	(1,585)
Issuances	0	0
Settlements	0	0
Transfers into Level 3	38	66
Transfers out of Level 3	(1,208)	(1,957)
Balance at December 31,	6,865	7,116	7,392
Changes in unrealized gains (losses) included in net income (loss) for the instruments still held at end of period	131	125	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	131	125	39
State and political subdivision
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance at January 1,	46	0
Total realized/unrealized gains (losses) included in net income (loss)	1	0	0
Total realized/unrealized gains (losses) included in AOCI	2	0	0
Purchases	0	46
Sales	0	0
Issuances	0	0
Settlements	0	0
Transfers into Level 3	16	0
Transfers out of Level 3	(38)	0
Balance at December 31,	27	46	0
Changes in unrealized gains (losses) included in net income (loss) for the instruments still held at end of period	2	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	2	0	0
Equity securities
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance at January 1,	432	345
Total realized/unrealized gains (losses) included in net income (loss)	(24)	22	17
Total realized/unrealized gains (losses) included in AOCI	7	(64)	(80)
Purchases	23	128
Sales	(41)	(96)
Issuances	0	0
Settlements	0	0
Transfers into Level 3	457	107
Transfers out of Level 3	(250)	(10)
Balance at December 31,	604	432	345
Changes in unrealized gains (losses) included in net income (loss) for the instruments still held at end of period	(29)	(1)	(5)
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	(29)	(1)	(5)
FVO And Trading Securities
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance at January 1,	270	567
Total realized/unrealized gains (losses) included in net income (loss)	2	(30)	8
Total realized/unrealized gains (losses) included in AOCI	0	0	0
Purchases	99	51
Sales	(35)	(127)
Issuances	0	0
Settlements	0	0
Transfers into Level 3	18	56
Transfers out of Level 3	(67)	(247)
Balance at December 31,	287	270	567
Changes in unrealized gains (losses) included in net income (loss) for the instruments still held at end of period	3	(27)	(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	3	(27)	(7)
Short-term Investments
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance at January 1,	291	336
Total realized/unrealized gains (losses) included in net income (loss)	1	1	1
Total realized/unrealized gains (losses) included in AOCI	4	(1)	0
Purchases	52	292
Sales	(51)	(27)
Issuances	0	0
Settlements	0	0
Transfers into Level 3	0	0
Transfers out of Level 3	(250)	(310)
Balance at December 31,	47	291	336
Changes in unrealized gains (losses) included in net income (loss) for the instruments still held at end of period	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	1	0	1
Separate Accounts
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance at January 1,	1,704	1,922
Total realized/unrealized gains (losses) included in net income (loss)	(3)	8	103
Total realized/unrealized gains (losses) included in AOCI	0	0	0
Purchases	377	572
Sales	(644)	(527)
Issuances	62	98
Settlements	(51)	(60)
Transfers into Level 3	19	1
Transfers out of Level 3	(312)	(310)
Balance at December 31,	1,152	1,704	1,922
Changes in unrealized gains (losses) included in net income (loss) for the instruments still held at end of period	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