Investments (Continuous Gross Unrealized Losses for Fixed Maturity Securities Available-For-Sale) (Details) $ in Millions	Mar. 31, 2021 USD ($)	Dec. 31, 2020 USD ($)
Debt Securities, Available-for-sale [Line Items]
Total number of securities in an unrealized loss position less than 12 months	4,117	2,177
Total number of securities in an unrealized loss position equal or greater than 12 months	852	690
Fixed Maturity Securities
Debt Securities, Available-for-sale [Line Items]
Less than 12 months Estimated Fair Value	$ 47,749	$ 27,727
Less than 12 months Gross Unrealized Loss	2,271	1,031
Equal to or Greater than 12 Months Estimated Fair Value	8,680	6,236
Equal to or Greater than 12 Months Gross Unrealized Loss	689	401
U.S. corporate
Debt Securities, Available-for-sale [Line Items]
Less than 12 months Estimated Fair Value	8,418	4,338
Less than 12 months Gross Unrealized Loss	441	196
Equal to or Greater than 12 Months Estimated Fair Value	1,380	506
Equal to or Greater than 12 Months Gross Unrealized Loss	98	50
Foreign government
Debt Securities, Available-for-sale [Line Items]
Less than 12 months Estimated Fair Value	8,983	6,795
Less than 12 months Gross Unrealized Loss	421	305
Equal to or Greater than 12 Months Estimated Fair Value	2,360	836
Equal to or Greater than 12 Months Gross Unrealized Loss	284	100
Foreign corporate
Debt Securities, Available-for-sale [Line Items]
Less than 12 months Estimated Fair Value	6,814	4,856
Less than 12 months Gross Unrealized Loss	305	321
Equal to or Greater than 12 Months Estimated Fair Value	2,247	1,255
Equal to or Greater than 12 Months Gross Unrealized Loss	216	147
U.S. government and agency
Debt Securities, Available-for-sale [Line Items]
Less than 12 months Estimated Fair Value	11,657	4,619
Less than 12 months Gross Unrealized Loss	779	87
Equal to or Greater than 12 Months Estimated Fair Value	76	33
Equal to or Greater than 12 Months Gross Unrealized Loss	15	2
RMBS
Debt Securities, Available-for-sale [Line Items]
Less than 12 months Estimated Fair Value	5,878	1,531
Less than 12 months Gross Unrealized Loss	178	27
Equal to or Greater than 12 Months Estimated Fair Value	450	152
Equal to or Greater than 12 Months Gross Unrealized Loss	18	14
ABS
Debt Securities, Available-for-sale [Line Items]
Less than 12 months Estimated Fair Value	2,519	3,428
Less than 12 months Gross Unrealized Loss	19	26
Equal to or Greater than 12 Months Estimated Fair Value	1,197	2,842
Equal to or Greater than 12 Months Gross Unrealized Loss	21	49
Municipals
Debt Securities, Available-for-sale [Line Items]
Less than 12 months Estimated Fair Value	1,802	273
Less than 12 months Gross Unrealized Loss	85	6
Equal to or Greater than 12 Months Estimated Fair Value	0	0
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	1,678	1,887
Less than 12 months Gross Unrealized Loss	43	63
Equal to or Greater than 12 Months Estimated Fair Value	970	612
Equal to or Greater than 12 Months Gross Unrealized Loss	37	39
Investment Grade
Debt Securities, Available-for-sale [Line Items]
Less than 12 months Estimated Fair Value	45,249	24,572
Less than 12 months Gross Unrealized Loss	2,166	829
Equal to or Greater than 12 Months Estimated Fair Value	7,132	5,841
Equal to or Greater than 12 Months Gross Unrealized Loss	534	350
Below Investment Grade
Debt Securities, Available-for-sale [Line Items]
Less than 12 months Estimated Fair Value	2,500	3,155
Less than 12 months Gross Unrealized Loss	105	202
Equal to or Greater than 12 Months Estimated Fair Value	1,548	395
Equal to or Greater than 12 Months Gross Unrealized Loss	$ 155	$ 51