Reclassifications Out of Accumulated Other Comprehensive Income (Detail) - USD ($) $ in Millions		3 Months Ended
		Mar. 31, 2016	Mar. 31, 2015
Reclassifications Out Of Accumulated Other Comprehensive Income [Line Items]
Income Before Income Taxes		$ 435	$ 485
Applicable income tax expense		108	124
Net income		327	361
Total Reclassifications For The Period
Reclassifications Out Of Accumulated Other Comprehensive Income [Line Items]
Net income		13	16
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		8	12
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]	8	12
Income Before Income Taxes	[1]	8	12
Applicable income tax expense	[1]	(3)	(4)
Net income	[1]	5	8
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		14	16
Income Before Income Taxes	[1]	14	16
Applicable income tax expense	[1]	(5)	(6)
Net income	[1]	9	10
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]	14	16
Amortization Of Defined Benefit Pension Items | Net Actuarial Loss
Reclassifications Out Of Accumulated Other Comprehensive Income [Line Items]
Net periodic pension cost	[1],[2]	(2)	(3)
Income Before Income Taxes	[1]	(2)	(3)
Applicable income tax expense	[1]	1	1
Net income	[1]	$ (1)	$ (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, 2015 for information on the computation of net periodic benefit cost.