Fair Value (Recurring Fair Value Measurements) (Details) - USD ($) $ in Millions	Dec. 31, 2018	Dec. 31, 2017
Assets [Abstract]
Debt Securities, Available-for-sale	$ 298,265	$ 308,931
Equity securities	1,440	2,513
Unit-linked and FVO Securities (1)	12,616	16,745
Short-term investments	3,937	4,870
Residential mortgage loans — FVO	75,752	68,731
Derivative assets	8,969	8,551
Embedded derivatives within asset host contracts	71	12
Separate account assets	175,556	205,001
Liabilities [Abstract]
Derivative liabilities	3,930	4,339
Embedded derivatives within liability host contracts	810	418
Separate account liabilities	175,556	205,001
Net Embedded Derivatives
Assets [Abstract]
Debt and equity securities also included in embedded derivatives	0	(132)
Residential mortgage loans - FVO
Assets [Abstract]
Residential mortgage loans — FVO	299	520
Recurring
Assets [Abstract]
Debt Securities, Available-for-sale	298,265	308,931
Equity securities	1,440	2,513
Unit-linked and FVO Securities (1)	12,616	16,745
Short-term investments	3,249	4,286
Other investments	237	165
Derivative assets	8,969	8,551
Embedded derivatives within asset host contracts	71	144
Separate account assets	175,556	205,001
Total assets (6)	500,702	546,856
Liabilities [Abstract]
Derivative liabilities	3,930	4,339
Embedded derivatives within liability host contracts	810	418
Total liabilities	4,768	4,766
Recurring | Interest rate contracts
Assets [Abstract]
Derivative assets	4,843	5,563
Liabilities [Abstract]
Derivative liabilities	415	772
Recurring | Foreign currency exchange rate contracts
Assets [Abstract]
Derivative assets	2,978	2,069
Liabilities [Abstract]
Derivative liabilities	2,749	2,590
Recurring | Credit contracts
Assets [Abstract]
Derivative assets	120	278
Liabilities [Abstract]
Derivative liabilities	52	43
Recurring | Equity market contracts
Assets [Abstract]
Derivative assets	1,028	641
Liabilities [Abstract]
Derivative liabilities	714	934
Recurring | Derivative Liabilities Within Separate Accounts
Liabilities [Abstract]
Separate account liabilities	28	9
Recurring | Residential mortgage loans - FVO
Assets [Abstract]
Residential mortgage loans — FVO	299	520
Recurring | U.S. corporate
Assets [Abstract]
Debt Securities, Available-for-sale	78,948	82,661
Recurring | Foreign government
Assets [Abstract]
Debt Securities, Available-for-sale	62,288	61,534
Recurring | Foreign corporate
Assets [Abstract]
Debt Securities, Available-for-sale	56,703	55,569
Recurring | U.S. government and agency
Assets [Abstract]
Debt Securities, Available-for-sale	39,322	47,394
Recurring | RMBS
Assets [Abstract]
Debt Securities, Available-for-sale	27,961	28,800
Recurring | ABS
Assets [Abstract]
Debt Securities, Available-for-sale	12,472	12,291
Recurring | Municipals
Assets [Abstract]
Debt Securities, Available-for-sale	11,533	12,455
Recurring | CMBS
Assets [Abstract]
Debt Securities, Available-for-sale	9,038	8,227
Recurring | Level 1
Assets [Abstract]
Debt Securities, Available-for-sale	19,656	26,052
Equity securities	916	1,104
Unit-linked and FVO Securities (1)	10,216	14,028
Short-term investments	1,470	3,001
Other investments	80	81
Derivative assets	18	22
Embedded derivatives within asset host contracts	0	0
Separate account assets	79,726	89,916
Total assets (6)	112,082	134,204
Liabilities [Abstract]
Derivative liabilities	80	8
Embedded derivatives within liability host contracts	0	0
Total liabilities	81	8
Recurring | Level 1 | Interest rate contracts
Assets [Abstract]
Derivative assets	1	2
Liabilities [Abstract]
Derivative liabilities	3	4
Recurring | Level 1 | Foreign currency exchange rate contracts
Assets [Abstract]
Derivative assets	4	2
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	13	18
Liabilities [Abstract]
Derivative liabilities	77	4
Recurring | Level 1 | Derivative Liabilities Within Separate Accounts
Liabilities [Abstract]
Separate account liabilities	1	0
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	19,656	26,052
Recurring | Level 1 | RMBS
Assets [Abstract]
Debt Securities, Available-for-sale	0	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	263,738	266,610
Equity securities	105	981
Unit-linked and FVO Securities (1)	1,995	2,355
Short-term investments	1,746	1,252
Other investments	118	84
Derivative assets	8,778	8,295
Embedded derivatives within asset host contracts	0	0
Separate account assets	94,886	114,124
Total assets (6)	371,366	393,701
Liabilities [Abstract]
Derivative liabilities	3,452	3,965
Embedded derivatives within liability host contracts	0	0
Total liabilities	3,472	3,972
Recurring | Level 2 | Interest rate contracts
Assets [Abstract]
Derivative assets	4,809	5,553
Liabilities [Abstract]
Derivative liabilities	194	638
Recurring | Level 2 | Foreign currency exchange rate contracts
Assets [Abstract]
Derivative assets	2,922	1,954
Liabilities [Abstract]
Derivative liabilities	2,660	2,553
Recurring | Level 2 | Credit contracts
Assets [Abstract]
Derivative assets	91	240
Liabilities [Abstract]
Derivative liabilities	48	43
Recurring | Level 2 | Equity market contracts
Assets [Abstract]
Derivative assets	956	548
Liabilities [Abstract]
Derivative liabilities	550	731
Recurring | Level 2 | Derivative Liabilities Within Separate Accounts
Liabilities [Abstract]
Separate account liabilities	20	7
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	74,874	78,171
Recurring | Level 2 | Foreign government
Assets [Abstract]
Debt Securities, Available-for-sale	62,150	61,325
Recurring | Level 2 | Foreign corporate
Assets [Abstract]
Debt Securities, Available-for-sale	50,310	48,840
Recurring | Level 2 | U.S. government and agency
Assets [Abstract]
Debt Securities, Available-for-sale	19,666	21,342
Recurring | Level 2 | RMBS
Assets [Abstract]
Debt Securities, Available-for-sale	24,734	25,339
Recurring | Level 2 | ABS
Assets [Abstract]
Debt Securities, Available-for-sale	11,775	11,204
Recurring | Level 2 | Municipals
Assets [Abstract]
Debt Securities, Available-for-sale	11,533	12,455
Recurring | Level 2 | CMBS
Assets [Abstract]
Debt Securities, Available-for-sale	8,696	7,934
Recurring | Level 3
Assets [Abstract]
Debt Securities, Available-for-sale	14,871	16,269
Equity securities	419	428
Unit-linked and FVO Securities (1)	405	362
Short-term investments	33	33
Other investments	39	0
Derivative assets	173	234
Embedded derivatives within asset host contracts	71	144
Separate account assets	944	961
Total assets (6)	17,254	18,951
Liabilities [Abstract]
Derivative liabilities	398	366
Embedded derivatives within liability host contracts	810	418
Total liabilities	1,215	786
Recurring | Level 3 | Interest rate contracts
Assets [Abstract]
Derivative assets	33	8
Liabilities [Abstract]
Derivative liabilities	218	130
Recurring | Level 3 | Foreign currency exchange rate contracts
Assets [Abstract]
Derivative assets	52	113
Liabilities [Abstract]
Derivative liabilities	89	37
Recurring | Level 3 | Credit contracts
Assets [Abstract]
Derivative assets	29	38
Liabilities [Abstract]
Derivative liabilities	4	0
Recurring | Level 3 | Equity market contracts
Assets [Abstract]
Derivative assets	59	75
Liabilities [Abstract]
Derivative liabilities	87	199
Recurring | Level 3 | Derivative Liabilities Within Separate Accounts
Liabilities [Abstract]
Separate account liabilities	7	2
Recurring | Level 3 | Residential mortgage loans - FVO
Assets [Abstract]
Residential mortgage loans — FVO	299	520
Recurring | Level 3 | U.S. corporate
Assets [Abstract]
Debt Securities, Available-for-sale	4,074	4,490
Recurring | Level 3 | Foreign government
Assets [Abstract]
Debt Securities, Available-for-sale	138	209
Recurring | Level 3 | Foreign corporate
Assets [Abstract]
Debt Securities, Available-for-sale	6,393	6,729
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	3,227	3,461
Recurring | Level 3 | ABS
Assets [Abstract]
Debt Securities, Available-for-sale	697	1,087
Recurring | Level 3 | Municipals
Assets [Abstract]
Debt Securities, Available-for-sale	0	0
Recurring | Level 3 | CMBS
Assets [Abstract]
Debt Securities, Available-for-sale	342	$ 293
Other limited partnership interests | Recurring
Assets [Abstract]
Investments, Fair Value Disclosure	$ 145