Fair Value (Recurring Fair Value Measurements) (Details) - USD ($) $ in Millions	Jun. 30, 2020	Dec. 31, 2019
Assets [Abstract]
Fixed maturity securities, estimated fair value	$ 75,605	$ 69,977
Equity securities	129	147
Short-term Investments	3,592	1,482
Derivative assets: (1)	6,450	3,222
Embedded derivatives within asset host contracts	323	217
Separate account assets	92,698	99,668
Liabilities [Abstract]
Derivative liabilities: (1)	8,378	7,119
Embedded derivatives within liability host contracts	6,127	4,582
Recurring
Assets [Abstract]
Fixed maturity securities, estimated fair value	75,605	69,977
Equity securities	129	147
Short-term Investments	3,592	1,482
Derivative assets: (1)	6,127	3,005
Embedded derivatives within asset host contracts	323	217
Separate account assets	92,698	99,668
Total assets	178,474	174,496
Liabilities [Abstract]
Derivative liabilities: (1)	2,251	2,537
Embedded derivatives within liability host contracts	6,127	4,582
Total liabilities	8,378	7,119
Recurring | Interest rate
Assets [Abstract]
Derivative assets: (1)	4,503	1,778
Liabilities [Abstract]
Derivative liabilities: (1)	265	330
Recurring | Foreign currency exchange rate
Assets [Abstract]
Derivative assets: (1)	655	270
Liabilities [Abstract]
Derivative liabilities: (1)	15	43
Recurring | Credit
Assets [Abstract]
Derivative assets: (1)	19	36
Liabilities [Abstract]
Derivative liabilities: (1)	2
Recurring | Equity market
Assets [Abstract]
Derivative assets: (1)	950	921
Liabilities [Abstract]
Derivative liabilities: (1)	1,969	2,164
Recurring | U.S. Corporate
Assets [Abstract]
Fixed maturity securities, estimated fair value	33,645	30,591
Recurring | Foreign Corporate
Assets [Abstract]
Fixed maturity securities, estimated fair value	10,148	9,686
Recurring | RMBS
Assets [Abstract]
Fixed maturity securities, estimated fair value	8,500	9,030
Recurring | U.S. Government and Agency
Assets [Abstract]
Fixed maturity securities, estimated fair value	8,742	7,244
Recurring | CMBS
Assets [Abstract]
Fixed maturity securities, estimated fair value	6,174	5,714
Recurring | State and Political Subdivision
Assets [Abstract]
Fixed maturity securities, estimated fair value	4,157	4,011
Recurring | ABS
Assets [Abstract]
Fixed maturity securities, estimated fair value	2,458	1,950
Recurring | Foreign Government
Assets [Abstract]
Fixed maturity securities, estimated fair value	1,781	1,751
Recurring | Level 1
Assets [Abstract]
Fixed maturity securities, estimated fair value	1,741	1,542
Equity securities	13	14
Short-term Investments	2,446	1,004
Derivative assets: (1)	0	0
Embedded derivatives within asset host contracts	0	0
Separate account assets	159	180
Total assets	4,359	2,740
Liabilities [Abstract]
Derivative liabilities: (1)	0	0
Embedded derivatives within liability host contracts	0	0
Total liabilities	0	0
Recurring | Level 1 | Interest rate
Assets [Abstract]
Derivative assets: (1)	0	0
Liabilities [Abstract]
Derivative liabilities: (1)	0	0
Recurring | Level 1 | Foreign currency exchange rate
Assets [Abstract]
Derivative assets: (1)	0	0
Liabilities [Abstract]
Derivative liabilities: (1)	0	0
Recurring | Level 1 | Credit
Assets [Abstract]
Derivative assets: (1)	0	0
Liabilities [Abstract]
Derivative liabilities: (1)	0
Recurring | Level 1 | Equity market
Assets [Abstract]
Derivative assets: (1)	0	0
Liabilities [Abstract]
Derivative liabilities: (1)	0	0
Recurring | Level 1 | U.S. Corporate
Assets [Abstract]
Fixed maturity securities, estimated fair value	0	0
Recurring | Level 1 | Foreign Corporate
Assets [Abstract]
Fixed maturity securities, estimated fair value	0	0
Recurring | Level 1 | RMBS
Assets [Abstract]
Fixed maturity securities, estimated fair value	0	0
Recurring | Level 1 | U.S. Government and Agency
Assets [Abstract]
Fixed maturity securities, estimated fair value	1,741	1,542
Recurring | Level 1 | CMBS
Assets [Abstract]
Fixed maturity securities, estimated fair value	0	0
Recurring | Level 1 | State and Political Subdivision
Assets [Abstract]
Fixed maturity securities, estimated fair value	0	0
Recurring | Level 1 | ABS
Assets [Abstract]
Fixed maturity securities, estimated fair value	0	0
Recurring | Level 1 | Foreign Government
Assets [Abstract]
Fixed maturity securities, estimated fair value	0	0
Recurring | Level 2
Assets [Abstract]
Fixed maturity securities, estimated fair value	72,797	67,788
Equity securities	113	125
Short-term Investments	1,146	473
Derivative assets: (1)	6,077	2,918
Embedded derivatives within asset host contracts	0	0
Separate account assets	92,536	99,485
Total assets	172,669	170,789
Liabilities [Abstract]
Derivative liabilities: (1)	2,221	2,466
Embedded derivatives within liability host contracts	0	0
Total liabilities	2,221	2,466
Recurring | Level 2 | Interest rate
Assets [Abstract]
Derivative assets: (1)	4,503	1,778
Liabilities [Abstract]
Derivative liabilities: (1)	265	330
Recurring | Level 2 | Foreign currency exchange rate
Assets [Abstract]
Derivative assets: (1)	626	265
Liabilities [Abstract]
Derivative liabilities: (1)	15	43
Recurring | Level 2 | Credit
Assets [Abstract]
Derivative assets: (1)	11	25
Liabilities [Abstract]
Derivative liabilities: (1)	1
Recurring | Level 2 | Equity market
Assets [Abstract]
Derivative assets: (1)	937	850
Liabilities [Abstract]
Derivative liabilities: (1)	1,940	2,093
Recurring | Level 2 | U.S. Corporate
Assets [Abstract]
Fixed maturity securities, estimated fair value	32,946	30,266
Recurring | Level 2 | Foreign Corporate
Assets [Abstract]
Fixed maturity securities, estimated fair value	9,953	9,554
Recurring | Level 2 | RMBS
Assets [Abstract]
Fixed maturity securities, estimated fair value	8,460	8,986
Recurring | Level 2 | U.S. Government and Agency
Assets [Abstract]
Fixed maturity securities, estimated fair value	7,001	5,702
Recurring | Level 2 | CMBS
Assets [Abstract]
Fixed maturity securities, estimated fair value	6,148	5,714
Recurring | Level 2 | State and Political Subdivision
Assets [Abstract]
Fixed maturity securities, estimated fair value	4,157	3,938
Recurring | Level 2 | ABS
Assets [Abstract]
Fixed maturity securities, estimated fair value	2,351	1,877
Recurring | Level 2 | Foreign Government
Assets [Abstract]
Fixed maturity securities, estimated fair value	1,781	1,751
Recurring | Level 3
Assets [Abstract]
Fixed maturity securities, estimated fair value	1,067	647
Equity securities	3	8
Short-term Investments	0	5
Derivative assets: (1)	50	87
Embedded derivatives within asset host contracts	323	217
Separate account assets	3	3
Total assets	1,446	967
Liabilities [Abstract]
Derivative liabilities: (1)	30	71
Embedded derivatives within liability host contracts	6,127	4,582
Total liabilities	6,157	4,653
Recurring | Level 3 | Interest rate
Assets [Abstract]
Derivative assets: (1)	0	0
Liabilities [Abstract]
Derivative liabilities: (1)	0	0
Recurring | Level 3 | Foreign currency exchange rate
Assets [Abstract]
Derivative assets: (1)	29	5
Liabilities [Abstract]
Derivative liabilities: (1)	0	0
Recurring | Level 3 | Credit
Assets [Abstract]
Derivative assets: (1)	8	11
Liabilities [Abstract]
Derivative liabilities: (1)	1
Recurring | Level 3 | Equity market
Assets [Abstract]
Derivative assets: (1)	13	71
Liabilities [Abstract]
Derivative liabilities: (1)	29	71
Recurring | Level 3 | U.S. Corporate
Assets [Abstract]
Fixed maturity securities, estimated fair value	699	325
Recurring | Level 3 | Foreign Corporate
Assets [Abstract]
Fixed maturity securities, estimated fair value	195	132
Recurring | Level 3 | RMBS
Assets [Abstract]
Fixed maturity securities, estimated fair value	40	44
Recurring | Level 3 | U.S. Government and Agency
Assets [Abstract]
Fixed maturity securities, estimated fair value	0	0
Recurring | Level 3 | CMBS
Assets [Abstract]
Fixed maturity securities, estimated fair value	26	0
Recurring | Level 3 | State and Political Subdivision
Assets [Abstract]
Fixed maturity securities, estimated fair value	0	73
Recurring | Level 3 | ABS
Assets [Abstract]
Fixed maturity securities, estimated fair value	107	73
Recurring | Level 3 | Foreign Government
Assets [Abstract]
Fixed maturity securities, estimated fair value	$ 0	$ 0