Reclassifications Out of Accumulated Other Comprehensive Income (Detail) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2015		Mar. 31, 2014
Reclassifications Out Of Accumulated Other Comprehensive Income [Line Items]
Income Before Income Taxes	$ 485		$ 438
Applicable income tax expense	124		119
Net income	361		318
Total Reclassifications For The Period
Reclassifications Out Of Accumulated Other Comprehensive Income [Line Items]
Net income	16		9
Net Unrealized Gains On Available For Sale Securities
Reclassifications Out Of Accumulated Other Comprehensive Income [Line Items]
Reclassification adjustment for net losses (gains) included in net income	12		5
Net Unrealized Gains On Available For Sale Securities | Net Losses Included In Net Income
Reclassifications Out Of Accumulated Other Comprehensive Income [Line Items]
Reclassification adjustment for net losses (gains) included in net income	12	[1]	5	[1]
Income Before Income Taxes	12	[1]	5	[1]
Applicable income tax expense	(4)	[1]	(2)	[1]
Net income	8	[1]	3	[1]
Net Unrealized Gains On Cash Flow Hedge Activities
Reclassifications Out Of Accumulated Other Comprehensive Income [Line Items]
Reclassification adjustment for net gains on cash flow hedge derivatives included in net income	16		10
Income Before Income Taxes	16	[1]	10	[1]
Applicable income tax expense	(6)	[1]	(3)	[1]
Net income	10	[1]	7	[1]
Net Unrealized Gains On Cash Flow Hedge Activities | Interest Rate Contracts Related To C&I Loans
Reclassifications Out Of Accumulated Other Comprehensive Income [Line Items]
Reclassification adjustment for net gains on cash flow hedge derivatives included in net income	16	[1],[2]	10	[1],[2]
Amortization Of Defined Benefit Pension Items | Net Actuarial Loss
Reclassifications Out Of Accumulated Other Comprehensive Income [Line Items]
Net periodic pension cost	(3)	[1],[2]	(2)	[1],[2]
Income Before Income Taxes	(3)	[1]	(2)	[1]
Applicable income tax expense	1	[1]	1	[1]
Net income	$ (2)	[1]	$ (1)	[1]

[1] Amounts in parentheses indicate reductions to net income

[2] This AOCI component is included in the computation of net periodic benefit cost. Refer to Note 21 in the Bancorp’s Annual Report on Form 10-K for the year ended December 31, 2014 for information on the computation of net periodic benefit cost.