Investments (Consolidated Variable Interest Entities) (Details) - USD ($) $ in Millions	Jun. 30, 2021	Dec. 31, 2020
Variable Interest Entity [Line Items]
Total Assets	$ 773,253	$ 795,146
Total Liabilities	703,830	720,329
Consolidated Entities [Member] | Variable Interest Entity, Primary Beneficiary
Variable Interest Entity [Line Items]
Total Assets	403	349
Total Liabilities	10	6
Investment funds (1) | Consolidated Entities [Member] | Variable Interest Entity, Primary Beneficiary
Variable Interest Entity [Line Items]
Total Assets	319	258
Total Liabilities	10	1
Renewable energy partnership (1) | Consolidated Entities [Member] | Variable Interest Entity, Primary Beneficiary
Variable Interest Entity [Line Items]
Total Assets	82	87
Total Liabilities	0	0
Other Investments | Consolidated Entities [Member] | Variable Interest Entity, Primary Beneficiary
Variable Interest Entity [Line Items]
Total Assets	2	4
Total Liabilities	$ 0	$ 5