Reclassifications Out of Accumulated Other Comprehensive Income (Detail) - USD ($) $ in Millions		3 Months Ended		6 Months Ended
		Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Reclassifications Out Of Accumulated Other Comprehensive Income [Line Items]
Income Before Income Taxes		$ 417	$ 606	$ 902	$ 1,044
Applicable income tax expense		108	167	232	287
Net income		315	439	676	756
Total Reclassifications For The Period
Reclassifications Out Of Accumulated Other Comprehensive Income [Line Items]
Net income		7	14	23	23
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		(6)	14	6	19
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	[1]	(6)	14	6	19
Income Before Income Taxes	[1]	(6)	14	6	19
Applicable income tax expense	[1]	2	(5)	(2)	(7)
Net income	[1]	(4)	9	4	12
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		19	11	35	21
Income Before Income Taxes	[1]	19	11	35	21
Applicable income tax expense	[1]	(6)	(5)	(12)	(8)
Net income	[1]	13	6	23	13
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	[1]	19	11	35	21
Amortization Of Defined Benefit Pension Items | Net Actuarial Loss
Reclassifications Out Of Accumulated Other Comprehensive Income [Line Items]
Net periodic pension cost	[1],[2]	(3)	(1)	(6)	(3)
Income Before Income Taxes	[1]	(3)	(1)	(6)	(3)
Applicable income tax expense	[1]	1		2	1
Net income	[1]	$ (2)	$ (1)	$ (4)	$ (2)

[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.