Investments (Continuous Gross Unrealized Losses for Fixed Maturity Securities Available For Sale) Details (Details) $ in Millions	Sep. 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	1,772	1,059
Total number of securities in an unrealized loss position equal or greater than 12 months	411	802
Fixed maturity securities AFS
Debt Securities, Available-for-sale [Line Items]
Less than 12 months Estimated Fair Value	$ 22,424	$ 10,377
Less than 12 months Gross Unrealized Loss	1,026	248
Equal to or Greater than 12 Months Estimated Fair Value	3,309	9,562
Equal to or Greater than 12 Months Gross Unrealized Loss	239	683
U.S. corporate
Debt Securities, Available-for-sale [Line Items]
Less than 12 months Estimated Fair Value	4,316	2,036
Less than 12 months Gross Unrealized Loss	256	77
Equal to or Greater than 12 Months Estimated Fair Value	295	1,304
Equal to or Greater than 12 Months Gross Unrealized Loss	58	146
U.S. government and agency
Debt Securities, Available-for-sale [Line Items]
Less than 12 months Estimated Fair Value	3,158	1,552
Less than 12 months Gross Unrealized Loss	7	26
Equal to or Greater than 12 Months Estimated Fair Value	0	29
Equal to or Greater than 12 Months Gross Unrealized Loss	0	0
Foreign corporate
Debt Securities, Available-for-sale [Line Items]
Less than 12 months Estimated Fair Value	5,596	1,368
Less than 12 months Gross Unrealized Loss	568	93
Equal to or Greater than 12 Months Estimated Fair Value	94	3,499
Equal to or Greater than 12 Months Gross Unrealized Loss	36	424
RMBS
Debt Securities, Available-for-sale [Line Items]
Less than 12 months Estimated Fair Value	2,901	1,479
Less than 12 months Gross Unrealized Loss	34	15
Equal to or Greater than 12 Months Estimated Fair Value	131	524
Equal to or Greater than 12 Months Gross Unrealized Loss	13	12
ABS
Debt Securities, Available-for-sale [Line Items]
Less than 12 months Estimated Fair Value	4,460	2,428
Less than 12 months Gross Unrealized Loss	70	13
Equal to or Greater than 12 Months Estimated Fair Value	2,453	3,778
Equal to or Greater than 12 Months Gross Unrealized Loss	80	48
Municipals
Debt Securities, Available-for-sale [Line Items]
Less than 12 months Estimated Fair Value	127	508
Less than 12 months Gross Unrealized Loss	3	13
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	1,479	857
Less than 12 months Gross Unrealized Loss	60	5
Equal to or Greater than 12 Months Estimated Fair Value	249	212
Equal to or Greater than 12 Months Gross Unrealized Loss	18	12
Foreign government
Debt Securities, Available-for-sale [Line Items]
Less than 12 months Estimated Fair Value	387	149
Less than 12 months Gross Unrealized Loss	28	6
Equal to or Greater than 12 Months Estimated Fair Value	87	215
Equal to or Greater than 12 Months Gross Unrealized Loss	34	41
Investment Grade
Debt Securities, Available-for-sale [Line Items]
Less than 12 months Estimated Fair Value	18,308	9,288
Less than 12 months Gross Unrealized Loss	693	190
Equal to or Greater than 12 Months Estimated Fair Value	3,022	8,233
Equal to or Greater than 12 Months Gross Unrealized Loss	185	530
Below Investment Grade
Debt Securities, Available-for-sale [Line Items]
Less than 12 months Estimated Fair Value	4,116	1,089
Less than 12 months Gross Unrealized Loss	333	58
Equal to or Greater than 12 Months Estimated Fair Value	287	1,329
Equal to or Greater than 12 Months Gross Unrealized Loss	$ 54	$ 153