Summary of the ALLL and Related Loans and Leases Classified by Portfolio Segment (Parenthetical) (Detail) (USD $) In Millions, unless otherwise specified	3 Months Ended		12 Months Ended
	Mar. 31, 2015		Dec. 31, 2014		Mar. 31, 2014	Dec. 31, 2013
Financing Receivable, Allowance for Credit Losses [Line Items]
Allowance for loan and lease losses	$ 1,300	[1]	$ 1,322	[1]	$ 1,483	$ 1,582
Portfolio loans and leases	91,118	[2]	89,976	[3]
Recorded Investment	2,197	[4]	2,233	[5]
Variable Interest Entity, Primary Beneficiary
Financing Receivable, Allowance for Credit Losses [Line Items]
Allowance for loan and lease losses	23		22
Commercial | Variable Interest Entity, Primary Beneficiary
Financing Receivable, Allowance for Credit Losses [Line Items]
Allowance for loan and lease losses	10		10
Number of Contracts	5		5
Recorded Investment	28		28
Leveraged Leases
Financing Receivable, Allowance for Credit Losses [Line Items]
Allowance for loan and lease losses	6		6
Portfolio loans and leases	873		874
Residential Mortgage Loans
Financing Receivable, Allowance for Credit Losses [Line Items]
Portfolio loans and leases at fair value	$ 126		$ 108

[1] Includes $176 and $179 of cash and due from banks, $48 and $47 of commercial mortgage loans, $2,900 and $3,331 of automobile loans, $(23) and $(22) of ALLL, $26 and $25 of other assets, $4 and $5 of other liabilities, and $2,983 and $3,434 of long-term debt from consolidated VIEs that are included in their respective captions above at March 31, 2015 and December 31, 2014, respectively. For further information refer to Note 10.

[2] Excludes $126 of loans measured at fair value.

[3] Excludes $108 of loans measured at fair value.

[4] Includes $774, $538 and $405, respectively, of commercial, residential mortgage and consumer TDRs on accrual status; $205, $31 and $59, respectively, of commercial, residential mortgage and consumer TDRs on nonaccrual status.

[5] Includes $869, $485 and $420, respectively, of commercial, residential mortgage and consumer TDRs on accrual status; $214, $33 and $63, respectively, of commercial, residential mortgage and consumer TDRs on nonaccrual status. Excludes five restructured loans at December 31, 2014 associated with a consolidated VIE in which the Bancorp has no continuing credit risk due to the risk being assumed by a third party, with an unpaid principal balance of $28, a recorded investment of $28, and an allowance of $10.