Credit Quality - Recorded Investment in Portfolio Loans and Leases by Age and Class (Parenthetical) (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018	Dec. 31, 2018
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	$ 808		$ 808		$ 599
30-89 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	440		440		326
90 Days and Greater Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	368		368		273
Residential Mortgage Loans
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans measured at fair value on a recurring basis	184		184		179
Residential Mortgage Loans | Federal Housing Administration Loan
Financing Receivable, Recorded Investment, Past Due [Line Items]
Losses Due To Claim Denials And Curtailments	1	$ 1	1	$ 4
Residential Mortgage Loans | Federal Housing Administration Loan | 30-89 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	96		96		90
Residential Mortgage Loans | Federal Housing Administration Loan | 90 Days and Greater Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	$ 274		$ 274		$ 195