Condensed Statement of Comprehensive Income - Parent Company Only (Detail) (USD $) In Millions, unless otherwise specified	12 Months Ended
Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Net income	$ 1,481us-gaap_NetIncomeLoss	$ 1,836us-gaap_NetIncomeLoss	$ 1,576us-gaap_NetIncomeLoss
Comprehensive Income (Loss), Net of Tax, Attributable to Parent [Abstract]
Unrealized gains on cash flow hedge derivatives	39	(8)	24
Other comprehensive income (loss), Net of Tax	347	(293)	(95)
Comprehensive income	1,830	1,533	1,479
Comprehensive income attributable to Bancorp	1,828us-gaap_ComprehensiveIncomeNetOfTax	1,543us-gaap_ComprehensiveIncomeNetOfTax	1,481us-gaap_ComprehensiveIncomeNetOfTax
Parent Company Only
Net income	1,481	1,836	1,576
Comprehensive Income (Loss), Net of Tax, Attributable to Parent [Abstract]
Unrealized gains on cash flow hedge derivatives			3
Other comprehensive income (loss), Net of Tax			3
Comprehensive income	$ 1,481	$ 1,836	$ 1,579

Amount after tax of increase (decrease) in equity from transactions and other events and circumstances from net income and other comprehensive income, attributable to parent entity. Excludes changes in equity resulting from investments by owners and distributions to owners.

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Amount after tax of increase (decrease) in equity from transactions and other events and circumstances from net income and other comprehensive income. Excludes changes in equity resulting from investments by owners and distributions to owners.

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The portion of profit or loss for the period, net of income taxes, which is attributable to the parent.

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Amount after tax and reclassification adjustments of other comprehensive income (loss).

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Amount after tax of increase (decrease) in accumulated gain (loss) from derivative instruments designated and qualifying as the effective portion of cash flow hedges and an entity's share of an equity investee's increase (decrease) in deferred hedging gain (loss).

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