Variable Interest Entities - Summary of Assets and Liabilities Related to Consolidated Variable Interest Entities (Details) - USD ($) $ in Millions		Dec. 31, 2020		Dec. 31, 2019		Dec. 31, 2018
Variable Interest Entity [Line Items]
Total assets		$ 196,434	[1]	$ 175,375	[1]	$ 172,448
Liabilities	[1]	178,143		157,119
Variable interest entities [Member]
Variable Interest Entity [Line Items]
Total assets		89		98
Liabilities		10		38
Low Income Housing Limited Liability Partnership [Member] | Variable interest entities [Member]
Variable Interest Entity [Line Items]
Total assets		79		98
Liabilities		9		38
Low Income Housing Limited Liability Partnership [Member] | Variable interest entities [Member] | Other assets [Member]
Variable Interest Entity [Line Items]
Total assets		79		98
Low Income Housing Limited Liability Partnership [Member] | Variable interest entities [Member] | Interest, taxes and other liabilities [Member]
Variable Interest Entity [Line Items]
Liabilities		9		38
Venture Debt Financing Entity [Member] | Variable interest entities [Member]
Variable Interest Entity [Line Items]
Total assets		10		0
Liabilities		1		0
Venture Debt Financing Entity [Member] | Variable interest entities [Member] | Loans [Member]
Variable Interest Entity [Line Items]
Total assets		10		0
Venture Debt Financing Entity [Member] | Variable interest entities [Member] | Interest, taxes and other liabilities [Member]
Variable Interest Entity [Line Items]
Liabilities		$ 1		$ 0

[1] Assets