Fair Value (Unobservable Input Reconciliation) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Residential mortgage loans - FVO
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance at January 1,	$ 520	$ 566
Total realized/unrealized gains (losses) included in net income (loss)	7	40	$ 8
Total realized/unrealized gains (losses) included in AOCI	0	0	0
Purchases	0	175
Sales	(162)	(179)
Issuances	0	0
Settlements	(66)	(82)
Transfers into Level 3	0	0
Transfers out of Level 3	0	0
Balance at December 31,	299	520	566
Changes in unrealized gains (losses) included in net income (loss) for the instruments still held at end of period	(15)	27	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	(15)	27	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	(59)	53	(56)
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Input Reconciliation [Roll Forward]
Balance at January 1,	(132)	(562)
Total realized/unrealized gains (losses) included in net income (loss)	(161)	87	(31)
Total realized/unrealized gains (losses) included in AOCI	(140)	216	(367)
Purchases	5	0
Sales	0	0
Issuances	(1)	(7)
Settlements	204	134
Transfers into Level 3	0	0
Transfers out of Level 3	0	0
Balance at December 31,	(225)	(132)	(562)
Changes in unrealized gains (losses) included in net income (loss) for the instruments still held at end of period	(59)	53	(56)
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	(150)	793	(242)
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Input Reconciliation [Roll Forward]
Balance at January 1,	(274)	(729)
Total realized/unrealized gains (losses) included in net income (loss)	(150)	823	(214)
Total realized/unrealized gains (losses) included in AOCI	(15)	(46)	(20)
Purchases	0	0
Sales	0	0
Issuances	0	0
Settlements	(300)	(322)
Transfers into Level 3	0	0
Transfers out of Level 3	0	0
Balance at December 31,	(739)	(274)	(729)
Changes in unrealized gains (losses) included in net income (loss) for the instruments still held at end of period	(150)	793	(242)
Corporate fixed maturity securities
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance at January 1,	11,219	11,537
Total realized/unrealized gains (losses) included in net income (loss)	9	3	5
Total realized/unrealized gains (losses) included in AOCI	(745)	708	59
Purchases	1,903	3,830
Sales	(1,464)	(1,763)
Issuances	0	0
Settlements	0	0
Transfers into Level 3	152	72
Transfers out of Level 3	(607)	(3,168)
Balance at December 31,	10,467	11,219	11,537
Changes in unrealized gains (losses) included in net income (loss) for the instruments still held at end of period	1	1	6
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	6
Foreign government
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance at January 1,	209	289
Total realized/unrealized gains (losses) included in net income (loss)	3	4	12
Total realized/unrealized gains (losses) included in AOCI	(14)	0	(42)
Purchases	5	30
Sales	(47)	(53)
Issuances	0	0
Settlements	0	0
Transfers into Level 3	0	5
Transfers out of Level 3	(18)	(66)
Balance at December 31,	138	209	289
Changes in unrealized gains (losses) included in net income (loss) for the instruments still held at end of period	1	4	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	1	4	12
Structured Securities
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance at January 1,	4,841	5,215
Total realized/unrealized gains (losses) included in net income (loss)	82	94	103
Total realized/unrealized gains (losses) included in AOCI	(23)	133	56
Purchases	1,142	1,376
Sales	(946)	(1,598)
Issuances	0	0
Settlements	0	0
Transfers into Level 3	59	70
Transfers out of Level 3	(889)	(449)
Balance at December 31,	4,266	4,841	5,215
Changes in unrealized gains (losses) included in net income (loss) for the instruments still held at end of period	70	84	103
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	70	84	103
Municipals
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance at January 1,	0	10
Total realized/unrealized gains (losses) included in net income (loss)	0	0	1
Total realized/unrealized gains (losses) included in AOCI	0	0	2
Purchases	0	0
Sales	0	0
Issuances	0	0
Settlements	0	0
Transfers into Level 3	0	0
Transfers out of Level 3	0	(10)
Balance at December 31,	0	0	10
Changes in unrealized gains (losses) included in net income (loss) for the instruments still held at end of period	0	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	0	1
Equity securities
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance at January 1,	428	468
Total realized/unrealized gains (losses) included in net income (loss)	(36)	0	(24)
Total realized/unrealized gains (losses) included in AOCI	0	19	19
Purchases	13	25
Sales	(28)	(51)
Issuances	0	0
Settlements	0	0
Transfers into Level 3	52	1
Transfers out of Level 3	(10)	(34)
Balance at December 31,	419	428	468
Changes in unrealized gains (losses) included in net income (loss) for the instruments still held at end of period	(26)	(17)	(29)
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	(26)	(17)	(29)
Unit-linked and FVO Securities
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance at January 1,	362	287
Total realized/unrealized gains (losses) included in net income (loss)	6	22	2
Total realized/unrealized gains (losses) included in AOCI	0	0	0
Purchases	263	292
Sales	(176)	(141)
Issuances	0	0
Settlements	0	0
Transfers into Level 3	9	8
Transfers out of Level 3	(59)	(106)
Balance at December 31,	405	362	287
Changes in unrealized gains (losses) included in net income (loss) for the instruments still held at end of period	8	19	3
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	19	3
Short-term Investments
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance at January 1,	33	46
Total realized/unrealized gains (losses) included in net income (loss)	(1)	0	1
Total realized/unrealized gains (losses) included in AOCI	(1)	0	4
Purchases	34	32
Sales	(12)	(1)
Issuances	0	0
Settlements	0	0
Transfers into Level 3	0	0
Transfers out of Level 3	(20)	(44)
Balance at December 31,	33	33	46
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
Other Investments [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance at January 1,	0	0
Total realized/unrealized gains (losses) included in net income (loss)	0	0	0
Total realized/unrealized gains (losses) included in AOCI	0	0	0
Purchases	39	0
Sales	0	0
Issuances	0	0
Settlements	0	0
Transfers into Level 3	0	0
Transfers out of Level 3	0	0
Balance at December 31,	39	0	0
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
Separate Accounts
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance at January 1,	959	1,141
Total realized/unrealized gains (losses) included in net income (loss)	7	(8)	(2)
Total realized/unrealized gains (losses) included in AOCI	0	0	0
Purchases	198	187
Sales	(168)	(80)
Issuances	(3)	1
Settlements	(1)	(93)
Transfers into Level 3	53	35
Transfers out of Level 3	(108)	(224)
Balance at December 31,	937	959	1,141
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