Investments (Unconsolidated Variable Interest Entities) (Details) - USD ($) $ in Millions	Mar. 31, 2019	Dec. 31, 2018
Variable Interest Entity [Line Items]
Carrying Amount Asset	$ 58,075	$ 56,649
Maximum Exposure to Loss	63,083	61,057
Tax Credits Guaranteed By Third Parties Amount That Reduces Maximum Exposure To Loss Related To Other Invested Assets	76	94
Other limited partnership interests
Variable Interest Entity [Line Items]
Carrying Amount Asset	5,772	5,641
Maximum Exposure to Loss	10,573	9,888
Other invested assets
Variable Interest Entity [Line Items]
Carrying Amount Asset	1,825	1,906
Maximum Exposure to Loss	1,960	2,063
Other
Variable Interest Entity [Line Items]
Carrying Amount Asset	349	296
Maximum Exposure to Loss	421	300
Structured securities (RMBS, CMBS, and ABS)
Variable Interest Entity [Line Items]
Carrying Amount Asset	48,865	47,874
Maximum Exposure to Loss	48,865	47,874
U.S. corporate and foreign corporate securities
Variable Interest Entity [Line Items]
Carrying Amount Asset	1,127	932
Maximum Exposure to Loss	1,127	932
Foreign government
Variable Interest Entity [Line Items]
Carrying Amount Asset	137	0
Maximum Exposure to Loss	$ 137	$ 0