Investments (Consolidated Variable Interest Entities) (Details) - USD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2019
Variable Interest Entity [Line Items]
Total assets	$ 795,146	$ 740,463
Total Liabilities	720,329	674,081
Consolidated Entities [Member] | Variable Interest Entity, Primary Beneficiary
Variable Interest Entity [Line Items]
Total assets	349	311
Total Liabilities	6	6
Investment funds (1) | Consolidated Entities [Member] | Variable Interest Entity, Primary Beneficiary
Variable Interest Entity [Line Items]
Total assets	258	207
Total Liabilities	1	1
Renewable energy partnership (1) | Consolidated Entities [Member] | Variable Interest Entity, Primary Beneficiary
Variable Interest Entity [Line Items]
Total assets	87	94
Total Liabilities	0	0
Other Investments | Consolidated Entities [Member] | Variable Interest Entity, Primary Beneficiary
Variable Interest Entity [Line Items]
Total assets	4	10
Total Liabilities	$ 5	$ 5