Fair Value (Recurring Fair Value Measurements) (Details) - USD ($) $ in Millions	Jun. 30, 2020	Dec. 31, 2019
Assets [Abstract]
Fixed maturity securities, estimated fair value	$ 76,796	$ 71,036
Equity securities	129	147
Short-term Investments	4,537	1,958
Derivative assets: (1)	6,473	3,238
Embedded derivatives within asset host contracts	323	217
Separate account assets	99,599	107,107
Liabilities [Abstract]
Derivative liabilities: (1)	7,900	6,785
Embedded derivatives within liability host contracts	5,649	4,248
Recurring
Assets [Abstract]
Fixed maturity securities, estimated fair value	76,796	71,036
Equity securities	129	147
Short-term Investments	4,537	1,958
Derivative assets: (1)	6,150	3,021
Embedded derivatives within asset host contracts	323	217
Separate account assets	99,599	107,107
Total assets	187,534	183,486
Liabilities [Abstract]
Derivative liabilities: (1)	2,251	2,537
Embedded derivatives within liability host contracts	5,649	4,248
Total liabilities	7,900	6,785
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)	678	286
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	34,265	31,160
Recurring | Foreign Corporate
Assets [Abstract]
Fixed maturity securities, estimated fair value	10,291	9,844
Recurring | RMBS
Assets [Abstract]
Fixed maturity securities, estimated fair value	8,584	9,118
Recurring | U.S. Government and Agency
Assets [Abstract]
Fixed maturity securities, estimated fair value	8,925	7,396
Recurring | CMBS
Assets [Abstract]
Fixed maturity securities, estimated fair value	6,255	5,755
Recurring | State and Political Subdivision
Assets [Abstract]
Fixed maturity securities, estimated fair value	4,232	4,057
Recurring | ABS
Assets [Abstract]
Fixed maturity securities, estimated fair value	2,463	1,955
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	1,858	1,636
Equity securities	12	14
Short-term Investments	3,007	1,271
Derivative assets: (1)	0	0
Embedded derivatives within asset host contracts	0	0
Separate account assets	159	180
Total assets	5,036	3,101
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	1,858	1,636
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	73,871	68,749
Equity securities	113	125
Short-term Investments	1,530	682
Derivative assets: (1)	6,100	2,934
Embedded derivatives within asset host contracts	0	0
Separate account assets	99,437	106,924
Total assets	181,051	179,414
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)	649	281
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	33,566	30,831
Recurring | Level 2 | Foreign Corporate
Assets [Abstract]
Fixed maturity securities, estimated fair value	10,096	9,712
Recurring | Level 2 | RMBS
Assets [Abstract]
Fixed maturity securities, estimated fair value	8,544	9,074
Recurring | Level 2 | U.S. Government and Agency
Assets [Abstract]
Fixed maturity securities, estimated fair value	7,067	5,760
Recurring | Level 2 | CMBS
Assets [Abstract]
Fixed maturity securities, estimated fair value	6,229	5,755
Recurring | Level 2 | State and Political Subdivision
Assets [Abstract]
Fixed maturity securities, estimated fair value	4,232	3,984
Recurring | Level 2 | ABS
Assets [Abstract]
Fixed maturity securities, estimated fair value	2,356	1,882
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	651
Equity securities	4	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	1,447	971
Liabilities [Abstract]
Derivative liabilities: (1)	30	71
Embedded derivatives within liability host contracts	5,649	4,248
Total liabilities	5,679	4,319
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	329
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