Summary of the ALLL and Related Loans and Leases Classified by Portfolio Segment (Parenthetical) (Detail) $ in Millions	3 Months Ended		12 Months Ended
	Mar. 31, 2016 USD ($) number		Dec. 31, 2015 USD ($) number		Mar. 31, 2015 USD ($)	Dec. 31, 2014 USD ($)
Financing Receivable, Allowance for Credit Losses [Line Items]
Allowance for loan and lease losses	$ 1,295	[1]	$ 1,272	[1]	$ 1,300	$ 1,322
Portfolio loans and leases	93,445	[2]	92,415	[3]
Recorded Investment	2,065	[4]	1,842	[5]
Variable Interest Entity, Primary Beneficiary
Financing Receivable, Allowance for Credit Losses [Line Items]
Allowance for loan and lease losses	27		28
Commercial | Variable Interest Entity, Primary Beneficiary
Financing Receivable, Allowance for Credit Losses [Line Items]
Allowance for loan and lease losses	$ 15		$ 15
Number of Contracts | number	5		5
Recorded Investment	$ 27		$ 27
Leveraged Leases
Financing Receivable, Allowance for Credit Losses [Line Items]
Allowance for loan and lease losses	5		5
Portfolio loans and leases	812		801
Residential Mortgage Loans
Financing Receivable, Allowance for Credit Losses [Line Items]
Portfolio loans and leases at fair value	$ 160		$ 167

[1] Includes $147 and $152 of cash and due from banks, $2,178 and $2,537 of portfolio loans and leases, $(27) and $(28) of ALLL, $11 and $14 of other assets, $4 and $3 of other liabilities, and $2,102 and $2,487 of long-term debt from consolidated VIEs that are included in their respective captions above at March 31, 2016 and December 31, 2015, respectively. For further information refer to Note 9.

[2] Excludes $160 of residential mortgage loans measured at fair value at March 31, 2016.

[3] Excludes $167 of residential mortgage loans measured at fair value at December 31, 2015.

[4] Includes $461, $636 and $362, respectively, of commercial, residential mortgage and consumer portfolio TDRs on accrual status and $210, $19 and $53, respectively, of commercial, residential mortgage and consumer portfolio TDRs on nonaccrual status at March 31, 2016.

[5] Includes $491, $607 and $372, respectively, of commercial, residential mortgage and consumer portfolio TDRs on accrual status and $203, $23 and $52, respectively, of commercial, residential mortgage and consumer portfolio TDRs on nonaccrual status at December 31, 2015.