Investments (Unconsolidated Variable Interest Entities) (Details) - USD ($) $ in Millions	Mar. 31, 2020	Dec. 31, 2019
Variable Interest Entity [Line Items]
Assets	$ 737,741	$ 740,463
Maximum Exposure to Loss	70,466	67,996
Tax Credits Guaranteed By Third Parties Amount That Reduces Maximum Exposure To Loss Related To Other Invested Assets	7	6
Structured Securities
Variable Interest Entity [Line Items]
Maximum Exposure to Loss	53,654	51,962
U.S. corporate and foreign corporate securities
Variable Interest Entity [Line Items]
Maximum Exposure to Loss	1,780	1,764
Foreign government
Variable Interest Entity [Line Items]
Maximum Exposure to Loss	124	136
Variable Interest Entity, Not Primary Beneficiary
Variable Interest Entity [Line Items]
Assets	64,633	62,481
Variable Interest Entity, Not Primary Beneficiary | Structured Securities
Variable Interest Entity [Line Items]
Assets	53,654	51,962
Variable Interest Entity, Not Primary Beneficiary | U.S. corporate and foreign corporate securities
Variable Interest Entity [Line Items]
Assets	1,780	1,764
Variable Interest Entity, Not Primary Beneficiary | Foreign government
Variable Interest Entity [Line Items]
Assets	124	136
Variable Interest Entity, Not Primary Beneficiary | Other limited partnership interests
Variable Interest Entity [Line Items]
Assets	7,164	6,674
Variable Interest Entity, Not Primary Beneficiary | Other invested assets
Variable Interest Entity [Line Items]
Assets	1,458	1,495
Variable Interest Entity, Not Primary Beneficiary | Other
Variable Interest Entity [Line Items]
Assets	453	450
Other limited partnership interests
Variable Interest Entity [Line Items]
Maximum Exposure to Loss	12,841	12,016
Other invested assets
Variable Interest Entity [Line Items]
Maximum Exposure to Loss	1,567	1,621
Other
Variable Interest Entity [Line Items]
Maximum Exposure to Loss	$ 500	$ 497