Fair Value (Unobservable Input Reconciliation) (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Residential mortgage loans - FVO
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance, beginning of period	$ 299	$ 520
Total realized/unrealized gains (losses) included in net income (loss)	2	2
Total realized/unrealized gains (losses) included in AOCI	0	0
Purchases	0	0
Sales	(16)	(64)
Issuances	0	0
Settlements	(9)	(20)
Transfers into Level 3	0	0
Transfers out of Level 3	0	0
Balance, end of period	276	438
Changes in unrealized gains (losses) included in net income (loss) for the instruments still held at end of period	0	(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	0	(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	48
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Input Reconciliation [Roll Forward]
Balance, beginning of period	(225)	(132)
Total realized/unrealized gains (losses) included in net income (loss)	70	11
Total realized/unrealized gains (losses) included in AOCI	97	(104)
Purchases	0	0
Sales	0	0
Issuances	0	0
Settlements	(11)	43
Transfers into Level 3	0	0
Transfers out of Level 3	0	0
Balance, end of period	(69)	(182)
Changes in unrealized gains (losses) included in net income (loss) for the instruments still held at end of period	69	48
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	192	31
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Input Reconciliation [Roll Forward]
Balance, beginning of period	(739)	(274)
Total realized/unrealized gains (losses) included in net income (loss)	193	36
Total realized/unrealized gains (losses) included in AOCI	7	(16)
Purchases	0	0
Sales	0	0
Issuances	0	0
Settlements	(66)	(74)
Transfers into Level 3	0	0
Transfers out of Level 3	0	0
Balance, end of period	(605)	(328)
Changes in unrealized gains (losses) included in net income (loss) for the instruments still held at end of period	192	31
Corporate fixed maturity securities
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance, beginning of period	10,467	11,219
Total realized/unrealized gains (losses) included in net income (loss)	9	7
Total realized/unrealized gains (losses) included in AOCI	394	(68)
Purchases	463	512
Sales	(270)	(542)
Issuances	0	0
Settlements	0	0
Transfers into Level 3	284	46
Transfers out of Level 3	(385)	(364)
Balance, end of period	10,962	10,810
Changes in unrealized gains (losses) included in net income (loss) for the instruments still held at end of period	(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)	1
Foreign government
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance, beginning of period	138	209
Total realized/unrealized gains (losses) included in net income (loss)	0	1
Total realized/unrealized gains (losses) included in AOCI	0	(3)
Purchases	20	2
Sales	(1)	(2)
Issuances	0	0
Settlements	0	0
Transfers into Level 3	0	0
Transfers out of Level 3	0	(28)
Balance, end of period	157	179
Changes in unrealized gains (losses) included in net income (loss) for the instruments still held at end of period	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
Structured Securities
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance, beginning of period	4,266	4,841
Total realized/unrealized gains (losses) included in net income (loss)	14	23
Total realized/unrealized gains (losses) included in AOCI	22	24
Purchases	264	657
Sales	(139)	(324)
Issuances	0	0
Settlements	0	0
Transfers into Level 3	1	45
Transfers out of Level 3	(359)	(684)
Balance, end of period	4,069	4,582
Changes in unrealized gains (losses) included in net income (loss) for the instruments still held at end of period	13	21
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	13	21
Equity Securities
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance, beginning of period	419	428
Total realized/unrealized gains (losses) included in net income (loss)	30	(6)
Total realized/unrealized gains (losses) included in AOCI	0	0
Purchases	6	1
Sales	(21)	(1)
Issuances	0	0
Settlements	0	0
Transfers into Level 3	0	0
Transfers out of Level 3	0	0
Balance, end of period	434	422
Changes in unrealized gains (losses) included in net income (loss) for the instruments still held at end of period	23	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	23	0
Unit-linked and FVO Securities
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance, beginning of period	405	362
Total realized/unrealized gains (losses) included in net income (loss)	14	5
Total realized/unrealized gains (losses) included in AOCI	0	0
Purchases	41	27
Sales	(3)	(59)
Issuances	0	0
Settlements	0	0
Transfers into Level 3	4	0
Transfers out of Level 3	(4)	(49)
Balance, end of period	457	286
Changes in unrealized gains (losses) included in net income (loss) for the instruments still held at end of period	15	4
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	4
Short-term Investments
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance, beginning of period	33	33
Total realized/unrealized gains (losses) included in net income (loss)	0	0
Total realized/unrealized gains (losses) included in AOCI	1	0
Purchases	110	605
Sales	(6)	(3)
Issuances	0	0
Settlements	0	0
Transfers into Level 3	0	0
Transfers out of Level 3	0	(20)
Balance, end of period	138	615
Changes in unrealized gains (losses) included in net income (loss) for the instruments still held at end of period	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
Other Investments
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance, beginning of period	39	0
Total realized/unrealized gains (losses) included in net income (loss)	0	0
Total realized/unrealized gains (losses) included in AOCI	0	0
Purchases	129	0
Sales	0	0
Issuances	0	0
Settlements	0	0
Transfers into Level 3	0	0
Transfers out of Level 3	0	0
Balance, end of period	168	0
Changes in unrealized gains (losses) included in net income (loss) for the instruments still held at end of period	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
Separate Accounts
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance, beginning of period	937	959
Total realized/unrealized gains (losses) included in net income (loss)	3	2
Total realized/unrealized gains (losses) included in AOCI	0	0
Purchases	80	409
Sales	(122)	(124)
Issuances	2	1
Settlements	(1)	(1)
Transfers into Level 3	0	53
Transfers out of Level 3	(2)	(75)
Balance, end of period	897	1,224
Changes in unrealized gains (losses) included in net income (loss) for the instruments still held at end of period	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