Variable Interest Entities - Summary of Assets and Liabilities Related to Consolidated Variable Interest Entities (Details) - USD ($) $ in Millions		Mar. 31, 2020		Dec. 31, 2019		Mar. 31, 2019
Variable Interest Entity [Line Items]
Total assets		$ 205,077	[1]	$ 175,375	[1]	$ 180,921
Liabilities	[1]	186,758		157,119
Variable interest entities [Member]
Variable Interest Entity [Line Items]
Total assets		131		98
Liabilities		32		38
Low Income Housing Limited Liability Partnership [Member] | Variable interest entities [Member]
Variable Interest Entity [Line Items]
Total assets		92		98
Liabilities		31		38
Low Income Housing Limited Liability Partnership [Member] | Variable interest entities [Member] | Other assets [Member]
Variable Interest Entity [Line Items]
Total assets		92		98
Low Income Housing Limited Liability Partnership [Member] | Variable interest entities [Member] | Interest, taxes and other liabilities [Member]
Variable Interest Entity [Line Items]
Liabilities		31		38
Venture Debt Financing Entity [Member] | Variable interest entities [Member]
Variable Interest Entity [Line Items]
Total assets		39		0
Liabilities		1		0
Venture Debt Financing Entity [Member] | Variable interest entities [Member] | Interest, taxes and other liabilities [Member]
Variable Interest Entity [Line Items]
Liabilities		1		0
Venture Debt Financing Entity [Member] | Variable interest entities [Member] | Loans [Member]
Variable Interest Entity [Line Items]
Total assets		$ 39		$ 0

[1] The following table summarizes assets and liabilities related to our consolidated variable interest entities ("VIEs") at March 31, 2020 and December 31, 2019 which are consolidated on our balance sheet. Assets and liabilities exclude intercompany balances that eliminate in consolidation. See Note 17, "Variable Interest Entities," for additional information. Assets: Loans $39 million and $0 million. Other assets $92 million and $98 million. Total assets $131 million and $98 million respectively. Liabilities: Interest, taxes and other liabilities $32 million and $38 million. Total liabilities $32 million and $38 million, respectively.