Fair Value (Recurring Fair Value Measurements) (Details) - USD ($) $ in Millions	Dec. 31, 2019	Dec. 31, 2018
Assets [Abstract]
Debt Securities, Available-for-sale	$ 327,820	$ 298,265
Equity securities	1,342	1,440
Unit-linked and FVO Securities (1)	13,102	12,616
Short-term investments	3,850	3,937
Residential mortgage loans — FVO	80,529	75,752
Derivative assets	10,084	8,969
Separate account assets	188,445	175,556
Liabilities [Abstract]
Derivative liabilities	3,737	3,930
Embedded derivatives within liability host contracts	802	810
Separate account liabilities	188,445	175,556
Residential mortgage loans - FVO
Assets [Abstract]
Residential mortgage loans — FVO	188	299
Recurring
Assets [Abstract]
Debt Securities, Available-for-sale	327,820	298,265
Equity securities	1,342	1,440
Unit-linked and FVO Securities (1)	13,102	12,616
Short-term investments	3,182	3,249
Other investments	689	237
Derivative assets	10,084	8,969
Embedded derivatives within asset host contracts	60	71
Separate account assets	188,445	175,556
Total assets (6)	544,912	500,702
Liabilities [Abstract]
Derivative liabilities	3,737	3,930
Embedded derivatives within liability host contracts	802	810
Total liabilities	4,561	4,768
Recurring | Interest rate contracts
Assets [Abstract]
Derivative assets	6,707	4,843
Liabilities [Abstract]
Derivative liabilities	418	415
Recurring | Foreign currency exchange rate contracts
Assets [Abstract]
Derivative assets	2,378	2,978
Liabilities [Abstract]
Derivative liabilities	2,442	2,749
Recurring | Credit contracts
Assets [Abstract]
Derivative assets	276	120
Liabilities [Abstract]
Derivative liabilities	103	52
Recurring | Equity market contracts
Assets [Abstract]
Derivative assets	723	1,028
Liabilities [Abstract]
Derivative liabilities	774	714
Recurring | Derivative Liabilities Within Separate Accounts
Liabilities [Abstract]
Separate account liabilities	22	28
Recurring | Residential mortgage loans - FVO
Assets [Abstract]
Residential mortgage loans — FVO	188	299
Recurring | U.S. corporate
Assets [Abstract]
Debt Securities, Available-for-sale	87,753	78,948
Recurring | Foreign government
Assets [Abstract]
Debt Securities, Available-for-sale	67,229	62,288
Recurring | Foreign corporate
Assets [Abstract]
Debt Securities, Available-for-sale	64,165	56,703
Recurring | U.S. government and agency
Assets [Abstract]
Debt Securities, Available-for-sale	42,084	39,322
Recurring | RMBS
Assets [Abstract]
Debt Securities, Available-for-sale	28,547	27,961
Recurring | ABS
Assets [Abstract]
Debt Securities, Available-for-sale	14,542	12,472
Recurring | Municipals
Assets [Abstract]
Debt Securities, Available-for-sale	13,053	11,533
Recurring | CMBS
Assets [Abstract]
Debt Securities, Available-for-sale	10,447	9,038
Recurring | Level 1
Assets [Abstract]
Debt Securities, Available-for-sale	21,061	19,656
Equity securities	794	916
Unit-linked and FVO Securities (1)	10,598	10,216
Short-term investments	2,042	1,470
Other investments	74	80
Derivative assets	15	18
Embedded derivatives within asset host contracts	0	0
Separate account assets	86,790	79,726
Total assets (6)	121,374	112,082
Liabilities [Abstract]
Derivative liabilities	11	80
Embedded derivatives within liability host contracts	0	0
Total liabilities	12	81
Recurring | Level 1 | Interest rate contracts
Assets [Abstract]
Derivative assets	2	1
Liabilities [Abstract]
Derivative liabilities	3	3
Recurring | Level 1 | Foreign currency exchange rate contracts
Assets [Abstract]
Derivative assets	7	4
Liabilities [Abstract]
Derivative liabilities	0	0
Recurring | Level 1 | Credit contracts
Assets [Abstract]
Derivative assets	0	0
Liabilities [Abstract]
Derivative liabilities	0	0
Recurring | Level 1 | Equity market contracts
Assets [Abstract]
Derivative assets	6	13
Liabilities [Abstract]
Derivative liabilities	8	77
Recurring | Level 1 | Derivative Liabilities Within Separate Accounts
Liabilities [Abstract]
Separate account liabilities	1	1
Recurring | Level 1 | Residential mortgage loans - FVO
Assets [Abstract]
Residential mortgage loans — FVO	0	0
Recurring | Level 1 | U.S. corporate
Assets [Abstract]
Debt Securities, Available-for-sale	0	0
Recurring | Level 1 | Foreign government
Assets [Abstract]
Debt Securities, Available-for-sale	0	0
Recurring | Level 1 | Foreign corporate
Assets [Abstract]
Debt Securities, Available-for-sale	0	0
Recurring | Level 1 | U.S. government and agency
Assets [Abstract]
Debt Securities, Available-for-sale	21,058	19,656
Recurring | Level 1 | RMBS
Assets [Abstract]
Debt Securities, Available-for-sale	3	0
Recurring | Level 1 | ABS
Assets [Abstract]
Debt Securities, Available-for-sale	0	0
Recurring | Level 1 | Municipals
Assets [Abstract]
Debt Securities, Available-for-sale	0	0
Recurring | Level 1 | CMBS
Assets [Abstract]
Debt Securities, Available-for-sale	0	0
Recurring | Level 2
Assets [Abstract]
Debt Securities, Available-for-sale	287,948	263,738
Equity securities	118	105
Unit-linked and FVO Securities (1)	1,879	1,995
Short-term investments	1,108	1,746
Other investments	160	118
Derivative assets	9,882	8,778
Embedded derivatives within asset host contracts	0	0
Separate account assets	100,668	94,886
Total assets (6)	401,763	371,366
Liabilities [Abstract]
Derivative liabilities	3,393	3,452
Embedded derivatives within liability host contracts	0	0
Total liabilities	3,407	3,472
Recurring | Level 2 | Interest rate contracts
Assets [Abstract]
Derivative assets	6,616	4,809
Liabilities [Abstract]
Derivative liabilities	220	194
Recurring | Level 2 | Foreign currency exchange rate contracts
Assets [Abstract]
Derivative assets	2,336	2,922
Liabilities [Abstract]
Derivative liabilities	2,324	2,660
Recurring | Level 2 | Credit contracts
Assets [Abstract]
Derivative assets	244	91
Liabilities [Abstract]
Derivative liabilities	102	48
Recurring | Level 2 | Equity market contracts
Assets [Abstract]
Derivative assets	686	956
Liabilities [Abstract]
Derivative liabilities	747	550
Recurring | Level 2 | Derivative Liabilities Within Separate Accounts
Liabilities [Abstract]
Separate account liabilities	14	20
Recurring | Level 2 | Residential mortgage loans - FVO
Assets [Abstract]
Residential mortgage loans — FVO	0	0
Recurring | Level 2 | U.S. corporate
Assets [Abstract]
Debt Securities, Available-for-sale	81,501	74,874
Recurring | Level 2 | Foreign government
Assets [Abstract]
Debt Securities, Available-for-sale	67,112	62,150
Recurring | Level 2 | Foreign corporate
Assets [Abstract]
Debt Securities, Available-for-sale	56,188	50,310
Recurring | Level 2 | U.S. government and agency
Assets [Abstract]
Debt Securities, Available-for-sale	21,026	19,666
Recurring | Level 2 | RMBS
Assets [Abstract]
Debt Securities, Available-for-sale	25,682	24,734
Recurring | Level 2 | ABS
Assets [Abstract]
Debt Securities, Available-for-sale	13,326	11,775
Recurring | Level 2 | Municipals
Assets [Abstract]
Debt Securities, Available-for-sale	13,046	11,533
Recurring | Level 2 | CMBS
Assets [Abstract]
Debt Securities, Available-for-sale	10,067	8,696
Recurring | Level 3
Assets [Abstract]
Debt Securities, Available-for-sale	18,811	14,871
Equity securities	430	419
Unit-linked and FVO Securities (1)	625	405
Short-term investments	32	33
Other investments	455	39
Derivative assets	187	173
Embedded derivatives within asset host contracts	60	71
Separate account assets	987	944
Total assets (6)	21,775	17,254
Liabilities [Abstract]
Derivative liabilities	333	398
Embedded derivatives within liability host contracts	802	810
Total liabilities	1,142	1,215
Recurring | Level 3 | Interest rate contracts
Assets [Abstract]
Derivative assets	89	33
Liabilities [Abstract]
Derivative liabilities	195	218
Recurring | Level 3 | Foreign currency exchange rate contracts
Assets [Abstract]
Derivative assets	35	52
Liabilities [Abstract]
Derivative liabilities	118	89
Recurring | Level 3 | Credit contracts
Assets [Abstract]
Derivative assets	32	29
Liabilities [Abstract]
Derivative liabilities	1	4
Recurring | Level 3 | Equity market contracts
Assets [Abstract]
Derivative assets	31	59
Liabilities [Abstract]
Derivative liabilities	19	87
Recurring | Level 3 | Derivative Liabilities Within Separate Accounts
Liabilities [Abstract]
Separate account liabilities	7	7
Recurring | Level 3 | Residential mortgage loans - FVO
Assets [Abstract]
Residential mortgage loans — FVO	188	299
Recurring | Level 3 | U.S. corporate
Assets [Abstract]
Debt Securities, Available-for-sale	6,252	4,074
Recurring | Level 3 | Foreign government
Assets [Abstract]
Debt Securities, Available-for-sale	117	138
Recurring | Level 3 | Foreign corporate
Assets [Abstract]
Debt Securities, Available-for-sale	7,977	6,393
Recurring | Level 3 | U.S. government and agency
Assets [Abstract]
Debt Securities, Available-for-sale	0	0
Recurring | Level 3 | RMBS
Assets [Abstract]
Debt Securities, Available-for-sale	2,862	3,227
Recurring | Level 3 | ABS
Assets [Abstract]
Debt Securities, Available-for-sale	1,216	697
Recurring | Level 3 | Municipals
Assets [Abstract]
Debt Securities, Available-for-sale	7	0
Recurring | Level 3 | CMBS
Assets [Abstract]
Debt Securities, Available-for-sale	380	342
Other limited partnership interests | Recurring
Assets [Abstract]
Investments, Fair Value Disclosure	$ 95	$ 145