Investments (Consolidated Variable Interest Entities) (Details) - USD ($) $ in Millions	Mar. 31, 2021	Dec. 31, 2020
Variable Interest Entity [Line Items]
Total Assets	$ 769,814	$ 795,146
Total Liabilities	703,677	720,329
Consolidated Entities [Member] | Variable Interest Entity, Primary Beneficiary
Variable Interest Entity [Line Items]
Total Assets	388	349
Total Liabilities	1	6
Investment funds (1) | Consolidated Entities [Member] | Variable Interest Entity, Primary Beneficiary
Variable Interest Entity [Line Items]
Total Assets	300	258
Total Liabilities	1	1
Renewable energy partnership (1) | Consolidated Entities [Member] | Variable Interest Entity, Primary Beneficiary
Variable Interest Entity [Line Items]
Total Assets	87	87
Total Liabilities	0	0
Other Investments | Consolidated Entities [Member] | Variable Interest Entity, Primary Beneficiary
Variable Interest Entity [Line Items]
Total Assets	1	4
Total Liabilities	$ 0	$ 5