Fair Value (Recurring Fair Value Measurements) (Details) - USD ($) $ in Millions	Sep. 30, 2020	Dec. 31, 2019
Assets [Abstract]
Fixed maturity securities, estimated fair value	$ 79,338	$ 71,036
Equity securities	117	147
Short-term Investments	4,239	1,958
Derivative assets: (1)	5,152	3,238
Embedded derivatives within asset host contracts	321	217
Separate account assets	103,184	107,107
Liabilities [Abstract]
Derivative liabilities: (1)	7,952	6,785
Embedded derivatives within liability host contracts	6,449	4,248
Recurring
Assets [Abstract]
Fixed maturity securities, estimated fair value	79,338	71,036
Equity securities	117	147
Short-term Investments	4,239	1,958
Derivative assets: (1)	4,831	3,021
Embedded derivatives within asset host contracts	321	217
Separate account assets	103,184	107,107
Total assets	192,030	183,486
Liabilities [Abstract]
Derivative liabilities: (1)	1,503	2,537
Embedded derivatives within liability host contracts	6,449	4,248
Total liabilities	7,952	6,785
Recurring | Interest rate
Assets [Abstract]
Derivative assets: (1)	3,458	1,778
Liabilities [Abstract]
Derivative liabilities: (1)	226	330
Recurring | Foreign currency exchange rate
Assets [Abstract]
Derivative assets: (1)	455	286
Liabilities [Abstract]
Derivative liabilities: (1)	37	43
Recurring | Credit
Assets [Abstract]
Derivative assets: (1)	27	36
Liabilities [Abstract]
Derivative liabilities: (1)	1
Recurring | Equity market
Assets [Abstract]
Derivative assets: (1)	891	921
Liabilities [Abstract]
Derivative liabilities: (1)	1,239	2,164
Recurring | U.S. Corporate
Assets [Abstract]
Fixed maturity securities, estimated fair value	35,906	31,160
Recurring | Foreign Corporate
Assets [Abstract]
Fixed maturity securities, estimated fair value	10,660	9,844
Recurring | RMBS
Assets [Abstract]
Fixed maturity securities, estimated fair value	8,449	9,118
Recurring | U.S. Government and Agency
Assets [Abstract]
Fixed maturity securities, estimated fair value	8,935	7,396
Recurring | CMBS
Assets [Abstract]
Fixed maturity securities, estimated fair value	6,425	5,755
Recurring | State and Political Subdivision
Assets [Abstract]
Fixed maturity securities, estimated fair value	4,429	4,057
Recurring | ABS
Assets [Abstract]
Fixed maturity securities, estimated fair value	2,714	1,955
Recurring | Foreign Government
Assets [Abstract]
Fixed maturity securities, estimated fair value	1,820	1,751
Recurring | Level 1
Assets [Abstract]
Fixed maturity securities, estimated fair value	1,849	1,636
Equity securities	15	14
Short-term Investments	3,019	1,271
Derivative assets: (1)	0	0
Embedded derivatives within asset host contracts	0	0
Separate account assets	153	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	1,849	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	76,330	68,749
Equity securities	99	125
Short-term Investments	1,210	682
Derivative assets: (1)	4,792	2,934
Embedded derivatives within asset host contracts	0	0
Separate account assets	103,028	106,924
Total assets	185,459	179,414
Liabilities [Abstract]
Derivative liabilities: (1)	1,479	2,466
Embedded derivatives within liability host contracts	0	0
Total liabilities	1,479	2,466
Recurring | Level 2 | Interest rate
Assets [Abstract]
Derivative assets: (1)	3,458	1,778
Liabilities [Abstract]
Derivative liabilities: (1)	226	330
Recurring | Level 2 | Foreign currency exchange rate
Assets [Abstract]
Derivative assets: (1)	438	281
Liabilities [Abstract]
Derivative liabilities: (1)	37	43
Recurring | Level 2 | Credit
Assets [Abstract]
Derivative assets: (1)	18	25
Liabilities [Abstract]
Derivative liabilities: (1)	0
Recurring | Level 2 | Equity market
Assets [Abstract]
Derivative assets: (1)	878	850
Liabilities [Abstract]
Derivative liabilities: (1)	1,216	2,093
Recurring | Level 2 | U.S. Corporate
Assets [Abstract]
Fixed maturity securities, estimated fair value	35,207	30,831
Recurring | Level 2 | Foreign Corporate
Assets [Abstract]
Fixed maturity securities, estimated fair value	10,281	9,712
Recurring | Level 2 | RMBS
Assets [Abstract]
Fixed maturity securities, estimated fair value	8,449	9,074
Recurring | Level 2 | U.S. Government and Agency
Assets [Abstract]
Fixed maturity securities, estimated fair value	7,086	5,760
Recurring | Level 2 | CMBS
Assets [Abstract]
Fixed maturity securities, estimated fair value	6,418	5,755
Recurring | Level 2 | State and Political Subdivision
Assets [Abstract]
Fixed maturity securities, estimated fair value	4,429	3,984
Recurring | Level 2 | ABS
Assets [Abstract]
Fixed maturity securities, estimated fair value	2,640	1,882
Recurring | Level 2 | Foreign Government
Assets [Abstract]
Fixed maturity securities, estimated fair value	1,820	1,751
Recurring | Level 3
Assets [Abstract]
Fixed maturity securities, estimated fair value	1,159	651
Equity securities	3	8
Short-term Investments	10	5
Derivative assets: (1)	39	87
Embedded derivatives within asset host contracts	321	217
Separate account assets	3	3
Total assets	1,535	971
Liabilities [Abstract]
Derivative liabilities: (1)	24	71
Embedded derivatives within liability host contracts	6,449	4,248
Total liabilities	6,473	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)	17	5
Liabilities [Abstract]
Derivative liabilities: (1)	0	0
Recurring | Level 3 | Credit
Assets [Abstract]
Derivative assets: (1)	9	11
Liabilities [Abstract]
Derivative liabilities: (1)	1
Recurring | Level 3 | Equity market
Assets [Abstract]
Derivative assets: (1)	13	71
Liabilities [Abstract]
Derivative liabilities: (1)	23	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	379	132
Recurring | Level 3 | RMBS
Assets [Abstract]
Fixed maturity securities, estimated fair value	0	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	7	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	74	73
Recurring | Level 3 | Foreign Government
Assets [Abstract]
Fixed maturity securities, estimated fair value	$ 0	$ 0