Loan Sale and Servicing Activities and Variable Interest Entities Loan Sale and Servicing Activities and Variable Interest Entities (Additional Information) (Details) - Low Income Housing Tax Credit Investments [Member] $ in Millions	3 Months Ended
	Mar. 31, 2020 USD ($)
Accounts, Notes, Loans and Financing Receivable [Line Items]
Other tax benefits recognized on low income housing tax credit investments	$ 12
New Accounting Pronouncement, Early Adoption, Effect [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Amortization recognized on low income housing tax credit investments	49
Tax credits recognized on low income housing tax credit investments	$ 50