Investments (Unconsolidated Variable Interest Entities) (Details) - USD ($) $ in Millions	Dec. 31, 2018	Dec. 31, 2017
Variable Interest Entity [Line Items]
Tax Credits Guaranteed By Third Parties Amount That Reduces Maximum Exposure To Loss Related To Other Invested Assets	$ 94	$ 117
Carrying Amount Asset	56,649	56,381
Variable Interest Entity, Reporting Entity Involvement, Maximum Loss Exposure, Amount	61,057	60,429
Other limited partnership interests
Variable Interest Entity [Line Items]
Carrying Amount Asset	5,641	4,834
Variable Interest Entity, Reporting Entity Involvement, Maximum Loss Exposure, Amount	9,888	8,543
Other invested assets
Variable Interest Entity [Line Items]
Carrying Amount Asset	1,906	2,291
Variable Interest Entity, Reporting Entity Involvement, Maximum Loss Exposure, Amount	2,063	2,625
Other
Variable Interest Entity [Line Items]
Carrying Amount Asset	296	82
Variable Interest Entity, Reporting Entity Involvement, Maximum Loss Exposure, Amount	300	87
Structured securities (RMBS, CMBS, and ABS)
Variable Interest Entity [Line Items]
Carrying Amount Asset	47,874	47,614
Variable Interest Entity, Reporting Entity Involvement, Maximum Loss Exposure, Amount	47,874	47,614
U.S. corporate and foreign corporate securities
Variable Interest Entity [Line Items]
Carrying Amount Asset	932	1,560
Variable Interest Entity, Reporting Entity Involvement, Maximum Loss Exposure, Amount	$ 932	$ 1,560