Variable Interest Entities - Additional Information (Details) - USD ($)	9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Dec. 31, 2019
Variable Interest Entity [Line Items]
VIE, assets that can only be used to settle obligations	$ 170,540,000,000		$ 144,988,000,000
VIE, liabilities	152,818,000,000		127,950,000,000
Recurring
Variable Interest Entity [Line Items]
Other investments	81,000,000		90,000,000
Variable Interest Entity, Not Primary Beneficiary
Variable Interest Entity [Line Items]
VIE, assets that can only be used to settle obligations	335,000,000		282,000,000
VIE, liabilities	1,000,000		1,000,000
Variable Interest Entity, Not Primary Beneficiary | LIHTC investments
Variable Interest Entity [Line Items]
VIE, assets that can only be used to settle obligations	6,693,000,000		6,405,000,000
VIE, liabilities	2,547,000,000		2,526,000,000
Tax credit of investment		$ 135,000,000
Variable Interest Entity, Not Primary Beneficiary | LIHTC investments | Qualified affordable housing projects investment
Variable Interest Entity [Line Items]
VIE, liabilities	477,000,000		546,000,000
Variable Interest Entity, Not Primary Beneficiary | LIHTC investments | Accrued Income And Other Assets
Variable Interest Entity [Line Items]
VIE, assets that can only be used to settle obligations	1,400,000,000		1,500,000,000
Variable Interest Entity, Not Primary Beneficiary | LIHTC investments | Investments
Variable Interest Entity [Line Items]
Amortization of investment	146,000,000	$ 137,000,000
Tax credit of investment	134,000,000
Variable Interest Entity, Not Primary Beneficiary | Measured at NAV | Recurring | Principal Investments, Indirect
Variable Interest Entity [Line Items]
Other investments	60,000,000		68,000,000
Variable Interest Entity, Primary Beneficiary | Investments
Variable Interest Entity [Line Items]
VIE, assets that can only be used to settle obligations	0		0
VIE, liabilities	$ 0		$ 0