Investments (Consolidated Variable Interest Entities) (Details) - USD ($) $ in Millions	Sep. 30, 2020	Dec. 31, 2019
Variable Interest Entity [Line Items]
Assets	$ 461,123	$ 430,817
Liabilities	425,495	398,205
Consolidated Entities | Variable Interest Entity, Primary Beneficiary
Variable Interest Entity [Line Items]
Assets	1,719	1,693
Liabilities	5	5
Real estate joint ventures | Variable Interest Entity, Primary Beneficiary | Parent Company
Variable Interest Entity [Line Items]
Assets	1,300	1,200
Real estate joint ventures | Variable Interest Entity, Primary Beneficiary | Affiliated Entity
Variable Interest Entity [Line Items]
Assets	131	129
Real estate joint ventures | Consolidated Entities | Variable Interest Entity, Primary Beneficiary
Variable Interest Entity [Line Items]
Assets	1,404	1,378
Liabilities	0	0
Mortgage loans | Variable Interest Entity, Primary Beneficiary | Parent Company
Variable Interest Entity [Line Items]
Assets	173	172
Mortgage loans | Variable Interest Entity, Primary Beneficiary | Affiliated Entity
Variable Interest Entity [Line Items]
Assets	39	39
Mortgage loans | Consolidated Entities | Variable Interest Entity, Primary Beneficiary
Variable Interest Entity [Line Items]
Assets	212	211
Liabilities	0	0
Renewable energy partnership | Consolidated Entities | Variable Interest Entity, Primary Beneficiary
Variable Interest Entity [Line Items]
Assets	93	94
Liabilities	0	0
Other | Consolidated Entities | Variable Interest Entity, Primary Beneficiary
Variable Interest Entity [Line Items]
Assets	10	10
Liabilities	$ 5	$ 5