Investments (Consolidated Variable Interest Entities) (Details) - USD ($) $ in Millions	Jun. 30, 2020	Dec. 31, 2019
Variable Interest Entity [Line Items]
Assets	$ 767,583	$ 740,463
Liabilities	691,643	674,081
Consolidated Entities [Member] | Variable Interest Entity, Primary Beneficiary [Member]
Variable Interest Entity [Line Items]
Assets	321	311
Liabilities	6	6
Investment Funds [Domain] | Consolidated Entities [Member] | Variable Interest Entity, Primary Beneficiary [Member]
Variable Interest Entity [Line Items]
Assets	218	207
Liabilities	1	1
Renewable energy partnership | Consolidated Entities [Member] | Variable Interest Entity, Primary Beneficiary [Member]
Variable Interest Entity [Line Items]
Assets	91	94
Liabilities	0	0
Other | Consolidated Entities [Member] | Variable Interest Entity, Primary Beneficiary [Member]
Variable Interest Entity [Line Items]
Assets	12	10
Liabilities	$ 5	$ 5