Investments (Continuous Gross Unrealized Losses for Fixed Maturity Securities Available-For-Sale) (Details) $ in Millions	Jun. 30, 2020 USD ($)	Dec. 31, 2019 USD ($)
Debt Securities, Available-for-sale [Line Items]
Total number of securities in an unrealized loss position less than 12 months	3,419	2,153
Total number of securities in an unrealized loss position equal or greater than 12 months	808	1,411
Fixed Maturity Securities
Debt Securities, Available-for-sale [Line Items]
Less than 12 months Estimated Fair Value	$ 41,247	$ 24,806
Less than 12 months Gross Unrealized Loss	2,460	578
Equal to or Greater than 12 Months Estimated Fair Value	7,342	15,700
Equal to or Greater than 12 Months Gross Unrealized Loss	688	1,069
U.S. corporate
Debt Securities, Available-for-sale [Line Items]
Less than 12 months Estimated Fair Value	9,285	3,817
Less than 12 months Gross Unrealized Loss	617	107
Equal to or Greater than 12 Months Estimated Fair Value	538	2,226
Equal to or Greater than 12 Months Gross Unrealized Loss	89	198
Foreign government
Debt Securities, Available-for-sale [Line Items]
Less than 12 months Estimated Fair Value	4,420	3,295
Less than 12 months Gross Unrealized Loss	244	149
Equal to or Greater than 12 Months Estimated Fair Value	1,259	1,490
Equal to or Greater than 12 Months Gross Unrealized Loss	130	172
Foreign corporate
Debt Securities, Available-for-sale [Line Items]
Less than 12 months Estimated Fair Value	11,997	3,188
Less than 12 months Gross Unrealized Loss	1,021	133
Equal to or Greater than 12 Months Estimated Fair Value	1,794	5,873
Equal to or Greater than 12 Months Gross Unrealized Loss	254	584
U.S. government and agency
Debt Securities, Available-for-sale [Line Items]
Less than 12 months Estimated Fair Value	2,033	5,391
Less than 12 months Gross Unrealized Loss	21	97
Equal to or Greater than 12 Months Estimated Fair Value	36	196
Equal to or Greater than 12 Months Gross Unrealized Loss	1	9
RMBS
Debt Securities, Available-for-sale [Line Items]
Less than 12 months Estimated Fair Value	2,620	2,341
Less than 12 months Gross Unrealized Loss	69	25
Equal to or Greater than 12 Months Estimated Fair Value	188	584
Equal to or Greater than 12 Months Gross Unrealized Loss	15	14
ABS
Debt Securities, Available-for-sale [Line Items]
Less than 12 months Estimated Fair Value	7,191	3,692
Less than 12 months Gross Unrealized Loss	249	22
Equal to or Greater than 12 Months Estimated Fair Value	3,127	4,843
Equal to or Greater than 12 Months Gross Unrealized Loss	157	66
Municipals
Debt Securities, Available-for-sale [Line Items]
Less than 12 months Estimated Fair Value	232	1,156
Less than 12 months Gross Unrealized Loss	4	29
Equal to or Greater than 12 Months Estimated Fair Value	0	1
Equal to or Greater than 12 Months Gross Unrealized Loss	0	0
CMBS
Debt Securities, Available-for-sale [Line Items]
Less than 12 months Estimated Fair Value	3,469	1,926
Less than 12 months Gross Unrealized Loss	235	16
Equal to or Greater than 12 Months Estimated Fair Value	400	487
Equal to or Greater than 12 Months Gross Unrealized Loss	42	26
Investment Grade
Debt Securities, Available-for-sale [Line Items]
Less than 12 months Estimated Fair Value	33,735	22,838
Less than 12 months Gross Unrealized Loss	1,840	437
Equal to or Greater than 12 Months Estimated Fair Value	6,372	13,813
Equal to or Greater than 12 Months Gross Unrealized Loss	549	821
Below Investment Grade
Debt Securities, Available-for-sale [Line Items]
Less than 12 months Estimated Fair Value	7,512	1,968
Less than 12 months Gross Unrealized Loss	620	141
Equal to or Greater than 12 Months Estimated Fair Value	970	1,887
Equal to or Greater than 12 Months Gross Unrealized Loss	$ 139	$ 248