Fair Value (Recurring Fair Value Measurements) (Details) - USD ($) $ in Millions	Sep. 30, 2020	Dec. 31, 2019
Assets [Abstract]
Fixed maturity securities, estimated fair value	$ 78,139	$ 69,977
Equity securities	114	147
Short-term Investments	3,341	1,482
Derivative assets: (1)	5,134	3,222
Embedded derivatives within asset host contracts	321	217
Separate account assets	95,955	99,668
Liabilities [Abstract]
Derivative liabilities: (1)	8,442	7,119
Embedded derivatives within liability host contracts	6,939	4,582
Recurring
Assets [Abstract]
Fixed maturity securities, estimated fair value	78,139	69,977
Equity securities	114	147
Short-term Investments	3,341	1,482
Derivative assets: (1)	4,813	3,005
Embedded derivatives within asset host contracts	321	217
Separate account assets	95,955	99,668
Total assets	182,683	174,496
Liabilities [Abstract]
Derivative liabilities: (1)	1,503	2,537
Embedded derivatives within liability host contracts	6,939	4,582
Total liabilities	8,442	7,119
Recurring | Interest rate
Assets [Abstract]
Derivative assets: (1)	3,458	1,778
Liabilities [Abstract]
Derivative liabilities: (1)	227	330
Recurring | Foreign currency exchange rate
Assets [Abstract]
Derivative assets: (1)	437	270
Liabilities [Abstract]
Derivative liabilities: (1)	36	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	35,294	30,591
Recurring | Foreign Corporate
Assets [Abstract]
Fixed maturity securities, estimated fair value	10,515	9,686
Recurring | RMBS
Assets [Abstract]
Fixed maturity securities, estimated fair value	8,370	9,030
Recurring | U.S. Government and Agency
Assets [Abstract]
Fixed maturity securities, estimated fair value	8,753	7,244
Recurring | CMBS
Assets [Abstract]
Fixed maturity securities, estimated fair value	6,332	5,714
Recurring | State and Political Subdivision
Assets [Abstract]
Fixed maturity securities, estimated fair value	4,346	4,011
Recurring | ABS
Assets [Abstract]
Fixed maturity securities, estimated fair value	2,710	1,950
Recurring | Foreign Government
Assets [Abstract]
Fixed maturity securities, estimated fair value	1,819	1,751
Recurring | Level 1
Assets [Abstract]
Fixed maturity securities, estimated fair value	1,733	1,542
Equity securities	12	14
Short-term Investments	2,451	1,004
Derivative assets: (1)	0	0
Embedded derivatives within asset host contracts	0	0
Separate account assets	153	180
Total assets	4,349	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	1,733	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	75,266	67,788
Equity securities	99	125
Short-term Investments	880	473
Derivative assets: (1)	4,774	2,918
Embedded derivatives within asset host contracts	0	0
Separate account assets	95,799	99,485
Total assets	176,818	170,789
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)	227	330
Recurring | Level 2 | Foreign currency exchange rate
Assets [Abstract]
Derivative assets: (1)	420	265
Liabilities [Abstract]
Derivative liabilities: (1)	36	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	34,595	30,266
Recurring | Level 2 | Foreign Corporate
Assets [Abstract]
Fixed maturity securities, estimated fair value	10,155	9,554
Recurring | Level 2 | RMBS
Assets [Abstract]
Fixed maturity securities, estimated fair value	8,370	8,986
Recurring | Level 2 | U.S. Government and Agency
Assets [Abstract]
Fixed maturity securities, estimated fair value	7,020	5,702
Recurring | Level 2 | CMBS
Assets [Abstract]
Fixed maturity securities, estimated fair value	6,325	5,714
Recurring | Level 2 | State and Political Subdivision
Assets [Abstract]
Fixed maturity securities, estimated fair value	4,346	3,938
Recurring | Level 2 | ABS
Assets [Abstract]
Fixed maturity securities, estimated fair value	2,636	1,877
Recurring | Level 2 | Foreign Government
Assets [Abstract]
Fixed maturity securities, estimated fair value	1,819	1,751
Recurring | Level 3
Assets [Abstract]
Fixed maturity securities, estimated fair value	1,140	647
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	1,516	967
Liabilities [Abstract]
Derivative liabilities: (1)	24	71
Embedded derivatives within liability host contracts	6,939	4,582
Total liabilities	6,963	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)	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	325
Recurring | Level 3 | Foreign Corporate
Assets [Abstract]
Fixed maturity securities, estimated fair value	360	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