Credit Quality - Recorded Investment in Portfolio Loans and Leases by Age and Class (Parenthetical) (Details) - USD ($) $ in Millions	3 Months Ended	6 Months Ended
	Jun. 30, 2018	Jun. 30, 2018	Jun. 30, 2019	Dec. 31, 2018
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due			$ 736	$ 599
30-89 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due			444	326
90 Days and Greater Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due			292	273
Residential Mortgage Loans
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans measured at fair value on a recurring basis			192	179
Residential Mortgage Loans | Federal Housing Administration Loan
Financing Receivable, Recorded Investment, Past Due [Line Items]
Losses Due To Claim Denials And Curtailments	$ 1	$ 3
Residential Mortgage Loans | Federal Housing Administration Loan | 30-89 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due			99	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			$ 266	$ 195