Credit Quality (Recorded Investment in Portfolio Loans and Leases by Age and Class) (Parenthetical) (Detail) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2019		Dec. 31, 2018
Financing Receivable, Recorded Investment, Past Due
Total Past Due		$ 653	[1]	$ 599	[2]
30-89 Days Past Due
Financing Receivable, Recorded Investment, Past Due
Total Past Due		364		326
90 Days and Greater Past Due
Financing Receivable, Recorded Investment, Past Due
Total Past Due		289		273
Post Earnings Adjustment		4
Residential Mortgage Loans
Financing Receivable, Recorded Investment, Past Due
Loans measured at fair value on a recurring basis		190		179
Residential Mortgage Loans | Federal Housing Administration Loan
Financing Receivable, Recorded Investment, Past Due
Losses Due To Claim Denials And Curtailments	$ 2
Residential Mortgage Loans | Federal Housing Administration Loan | 30-89 Days Past Due
Financing Receivable, Recorded Investment, Past Due
Total Past Due		97		90
Residential Mortgage Loans | Federal Housing Administration Loan | 90 Days and Greater Past Due
Financing Receivable, Recorded Investment, Past Due
Total Past Due		$ 262		$ 195

[1] Excludes $ 190 of residential mortgage loans measured at fair value at March 31, 2019 .

[2] Excludes $ 179 of residential mortgage loans measured at fair value at December 31, 2018 .