Investments - Summary of Maximum Loss Exposure (Details) - USD ($) $ in Millions	Sep. 30, 2020	Dec. 31, 2019
Variable Interest Entity [Line Items]
Assets	$ 191,088	$ 146,875
Variable Interest Entity, Reporting Entity Involvement, Maximum Loss Exposure, Amount	37,075	34,326
Investment funds
Variable Interest Entity [Line Items]
Variable Interest Entity, Reporting Entity Involvement, Maximum Loss Exposure, Amount	1,183	1,265
Related Party | Investment funds
Variable Interest Entity [Line Items]
Variable Interest Entity, Reporting Entity Involvement, Maximum Loss Exposure, Amount	7,256	5,955
Debt Securities [Member]
Variable Interest Entity [Line Items]
Variable Interest Entity, Reporting Entity Involvement, Maximum Loss Exposure, Amount	22,000	22,170
Debt Securities [Member] | Related Party
Variable Interest Entity [Line Items]
Variable Interest Entity, Reporting Entity Involvement, Maximum Loss Exposure, Amount	6,586	4,878
Equity securities | Related Party
Variable Interest Entity [Line Items]
Variable Interest Entity, Reporting Entity Involvement, Maximum Loss Exposure, Amount	50	58
Variable Interest Entity, Not Primary Beneficiary [Member]
Variable Interest Entity [Line Items]
Assets	33,729	31,622
Variable Interest Entity, Not Primary Beneficiary [Member] | Investment funds
Variable Interest Entity [Line Items]
Assets	723	750
Variable Interest Entity, Not Primary Beneficiary [Member] | Related Party | Investment funds
Variable Interest Entity [Line Items]
Assets	4,808	3,550
Variable Interest Entity, Not Primary Beneficiary [Member] | Debt Securities [Member]
Variable Interest Entity [Line Items]
Assets	21,930	22,694
Variable Interest Entity, Not Primary Beneficiary [Member] | Debt Securities [Member] | Related Party
Variable Interest Entity [Line Items]
Assets	6,218	4,570
Variable Interest Entity, Not Primary Beneficiary [Member] | Equity securities | Related Party
Variable Interest Entity [Line Items]
Assets	$ 50	$ 58