Fair Value (Unobservable Input Reconciliation) (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Residential mortgage loans - FVO
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance, beginning of period	$ 188	$ 299
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	(5)	(16)
Issuances	0	0
Settlements	(5)	(9)
Transfers into Level 3	0	0
Transfers out of Level 3	0	0
Balance, end of period	180	276
Changes in unrealized gains (losses) included in net income (loss) for the instruments still held at end of period	0	0
Changes in unrealized gains (losses) included in AOCI for the instruments still held at end of period	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
Changes in unrealized gains (losses) included in AOCI for the instruments still held at end of period	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	40	69
Changes in unrealized gains (losses) included in AOCI for the instruments still held at end of period	1,122
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Input Reconciliation [Roll Forward]
Balance, beginning of period	(146)	(225)
Total realized/unrealized gains (losses) included in net income (loss)	71	70
Total realized/unrealized gains (losses) included in AOCI	1,200	97
Purchases	(10)	0
Sales	0	0
Issuances	0	0
Settlements	(76)	(11)
Transfers into Level 3	0	0
Transfers out of Level 3	0	0
Balance, end of period	1,039	(69)
Changes in unrealized gains (losses) included in net income (loss) for the instruments still held at end of period	40	69
Changes in unrealized gains (losses) included in AOCI for the instruments still held at end of period	1,122
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	(1,422)	192
Changes in unrealized gains (losses) included in AOCI for the instruments still held at end of period	(4)
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Input Reconciliation [Roll Forward]
Balance, beginning of period	(742)	(739)
Total realized/unrealized gains (losses) included in net income (loss)	(1,422)	193
Total realized/unrealized gains (losses) included in AOCI	(4)	7
Purchases	0	0
Sales	0	0
Issuances	0	0
Settlements	(64)	(66)
Transfers into Level 3	0	0
Transfers out of Level 3	0	0
Balance, end of period	(2,232)	(605)
Changes in unrealized gains (losses) included in net income (loss) for the instruments still held at end of period	(1,422)	192
Changes in unrealized gains (losses) included in AOCI for the instruments still held at end of period	(4)
Corporate fixed maturity securities
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance, beginning of period	14,229	10,467
Total realized/unrealized gains (losses) included in net income (loss)	(60)	9
Total realized/unrealized gains (losses) included in AOCI	(1,200)	394
Purchases	2,392	463
Sales	(565)	(270)
Issuances	0	0
Settlements	0	0
Transfers into Level 3	5,503	284
Transfers out of Level 3	(490)	(385)
Balance, end of period	19,809	10,962
Changes in unrealized gains (losses) included in net income (loss) for the instruments still held at end of period	(59)	(1)
Changes in unrealized gains (losses) included in AOCI for the instruments still held at end of period	(1,201)
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	(59)	(1)
Changes in unrealized gains (losses) included in AOCI for the instruments still held at end of period	(1,201)
Foreign government
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance, beginning of period	117	138
Total realized/unrealized gains (losses) included in net income (loss)	(2)	0
Total realized/unrealized gains (losses) included in AOCI	(7)	0
Purchases	32	20
Sales	(3)	(1)
Issuances	0	0
Settlements	0	0
Transfers into Level 3	28	0
Transfers out of Level 3	(61)	0
Balance, end of period	104	157
Changes in unrealized gains (losses) included in net income (loss) for the instruments still held at end of period	(2)	0
Changes in unrealized gains (losses) included in AOCI for the instruments still held at end of period	(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	(2)	0
Changes in unrealized gains (losses) included in AOCI for the instruments still held at end of period	(7)
Structured Securities
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance, beginning of period	4,458	4,266
Total realized/unrealized gains (losses) included in net income (loss)	10	14
Total realized/unrealized gains (losses) included in AOCI	(311)	22
Purchases	372	264
Sales	(186)	(139)
Issuances	0	0
Settlements	0	0
Transfers into Level 3	45	1
Transfers out of Level 3	(374)	(359)
Balance, end of period	4,014	4,069
Changes in unrealized gains (losses) included in net income (loss) for the instruments still held at end of period	11	13
Changes in unrealized gains (losses) included in AOCI for the instruments still held at end of period	(312)
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	13
Changes in unrealized gains (losses) included in AOCI for the instruments still held at end of period	(312)
Municipals
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance, beginning of period	7	0
Total realized/unrealized gains (losses) included in net income (loss)	0	0
Total realized/unrealized gains (losses) included in AOCI	0	0
Purchases	0	0
Sales	0	0
Issuances	0	0
Settlements	0	0
Transfers into Level 3	0	0
Transfers out of Level 3	(7)	0
Balance, end of period	0	0
Changes in unrealized gains (losses) included in net income (loss) for the instruments still held at end of period	0	0
Changes in unrealized gains (losses) included in AOCI for the instruments still held at end of period	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
Changes in unrealized gains (losses) included in AOCI for the instruments still held at end of period	0
Equity Securities
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance, beginning of period	430	419
Total realized/unrealized gains (losses) included in net income (loss)	(28)	30
Total realized/unrealized gains (losses) included in AOCI	0	0
Purchases	2	6
Sales	(32)	(21)
Issuances	0	0
Settlements	0	0
Transfers into Level 3	0	0
Transfers out of Level 3	0	0
Balance, end of period	372	434
Changes in unrealized gains (losses) included in net income (loss) for the instruments still held at end of period	(12)	23
Changes in unrealized gains (losses) included in AOCI for the instruments still held at end of period	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	(12)	23
Changes in unrealized gains (losses) included in AOCI for the instruments still held at end of period	0
Unit-linked and FVO Securities
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance, beginning of period	625	405
Total realized/unrealized gains (losses) included in net income (loss)	(63)	14
Total realized/unrealized gains (losses) included in AOCI	0	0
Purchases	140	41
Sales	(103)	(3)
Issuances	0	0
Settlements	0	0
Transfers into Level 3	14	4
Transfers out of Level 3	(96)	(4)
Balance, end of period	517	457
Changes in unrealized gains (losses) included in net income (loss) for the instruments still held at end of period	(65)	15
Changes in unrealized gains (losses) included in AOCI for the instruments still held at end of period	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	(65)	15
Changes in unrealized gains (losses) included in AOCI for the instruments still held at end of period	0
Short-term Investments
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance, beginning of period	32	33
Total realized/unrealized gains (losses) included in net income (loss)	0	0
Total realized/unrealized gains (losses) included in AOCI	(1)	1
Purchases	354	110
Sales	(8)	(6)
Issuances	0	0
Settlements	0	0
Transfers into Level 3	5	0
Transfers out of Level 3	(14)	0
Balance, end of period	368	138
Changes in unrealized gains (losses) included in net income (loss) for the instruments still held at end of period	0	0
Changes in unrealized gains (losses) included in AOCI for the instruments still held at end of period	(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
Changes in unrealized gains (losses) included in AOCI for the instruments still held at end of period	(1)
Other Investments [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance, beginning of period	455	39
Total realized/unrealized gains (losses) included in net income (loss)	4	0
Total realized/unrealized gains (losses) included in AOCI	0	0
Purchases	16	129
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	475	168
Changes in unrealized gains (losses) included in net income (loss) for the instruments still held at end of period	0	0
Changes in unrealized gains (losses) included in AOCI for the instruments still held at end of period	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
Changes in unrealized gains (losses) included in AOCI for the instruments still held at end of period	0
Separate Accounts
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance, beginning of period	980	937
Total realized/unrealized gains (losses) included in net income (loss)	(8)	3
Total realized/unrealized gains (losses) included in AOCI	0	0
Purchases	144	80
Sales	(62)	(122)
Issuances	(1)	2
Settlements	0	(1)
Transfers into Level 3	10	0
Transfers out of Level 3	(17)	(2)
Balance, end of period	1,046	897
Changes in unrealized gains (losses) included in net income (loss) for the instruments still held at end of period	0	0
Changes in unrealized gains (losses) included in AOCI for the instruments still held at end of period	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
Changes in unrealized gains (losses) included in AOCI for the instruments still held at end of period	$ 0