Credit Quality (Summary of the ALLL and Related Loans and Leases Classified by Portfolio Segment) (Parenthetical) (Detail)		12 Months Ended
		Dec. 31, 2017 USD ($)		Dec. 31, 2016 USD ($)		Dec. 31, 2015 USD ($)	Dec. 31, 2014 USD ($)
Financing Receivable, Allowance for Credit Losses
Allowance for loan and lease losses		$ 1,196,000,000	[1]	$ 1,253,000,000	[1]	$ 1,272,000,000	$ 1,322,000,000
Portfolio loans and leases at fair value		$ 137,000,000		$ 143,000,000
Number of Contracts	[2],[3]	9,256		10,978		14,472
Recorded Investment		$ 1,545,000,000	[4]	$ 1,901,000,000	[5]
Variable Interest Entity, Primary Beneficiary
Financing Receivable, Allowance for Credit Losses
Allowance for loan and lease losses		6,000,000		26,000,000
Leveraged Leases
Financing Receivable, Allowance for Credit Losses
Allowance for loan and lease losses		1,000,000		2,000,000
Residential Portfolio Segment
Financing Receivable, Allowance for Credit Losses
Portfolio loans and leases at fair value		$ 137,000,000		$ 143,000,000

[1] Includes $ 0 and $ 85 of cash and due from banks, $ 62 and $ 0 of other short-term investments, $ 1,297 and $ 1,216 of portfolio loans and leases, $ (6) and $ (26) of ALLL, $ 7 and $ 9 of other assets, $ 2 and $ 3 of other liabilities and $ 1,190 and $ 1,094 of long-term debt from consolidated VIEs that are included in their respective captions above at December 31, 2017 and 2016 , respectively. For further information, refer to Note 11 .

[2] Represents number of loans post-modification and excludes loans previously modified in a TDR .

[3] Excludes all loans and leases held for sale and loans acquired with deteriorated credit quality which were accounted for within a pool .

[4] Includes $ 249 , $ 652 and $ 275 , respectively, of commercial, residential mortgage and consumer portfolio TDRs on accrual status and $ 150 , $ 13 and $ 45 , respectively, of commercial, residential mortgage and consumer portfolio TDRs on nonaccrual status at December 31, 2017 .

[5] Includes $ 322 , $ 635 and $ 323 , respectively, of commercial, residential mortgage and consumer portfolio TDRs on accrual status and $ 192 , $ 17 and $ 48 , respectively, of commercial, residential mortgage and consumer portfolio TDRs on nonaccrual status at December 31, 2016 .