Fair Value Measurements (Fair Value Measurements - Additional Information) (Detail) - USD ($) $ / shares in Units, shares in Millions, $ in Millions		3 Months Ended			9 Months Ended		12 Months Ended
		Sep. 30, 2016	Sep. 30, 2015	Mar. 31, 2015	Sep. 30, 2016	Sep. 30, 2015	Dec. 31, 2015	Jun. 30, 2009
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Net fair value of the interest rate lock commitments		$ 33			$ 33
Change in the fair value of the interest rate lock commitments, due to decrease in current interest rates of 25 bp		7			7
Change in the fair value of the interest rate lock commitments, due to decrease in current interest rates of 50 bp		14			14
Change in the fair value of the interest rate lock commitments, due to increase in current interest rates of 25 bp		8			8
Change in the fair value of the interest rate lock commitments, due to increase in current interest rates of 50 bp		17			17
Change in fair value of interest rate lock commitments, due to 10% adverse changes in the assumed loan closing rates		3			3
Change in fair value of interest rate lock commitments, due to 20% adverse changes in the assumed loan closing rates		7			7
Change in fair value of interest rate lock commitments, due to 10% favorable changes in the assumed loan closing rates		3			3
Change in fair value of interest rate lock commitments, due to 20% favorable changes in the assumed loan closing rates		7			7
Portfolio loans to loans held for sale					153	$ 470
Existing loans held for sale, further adjusted		$ 954			954		$ 519
Residential loans transferred to the Bancorp's portfolio					20	274
Fair value changes included in earnings for instruments for which the fair value option was elected					$ 49	32
Incremental Unit Purchase Option		7.8			7.8
Vantiv Holding, LLC Warrant Exercise Price		$ 15.98			$ 15.98
Percentage of Vantiv Holding, LLC sold to Advent for cash and warrants								51.00%
OTTI	[1]	$ 2	$ 0		$ 8	5
Commercial Loans Held For Sale
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Portfolio loans to loans held for sale		112			137	26
Net impact related to fair value adjustments						(1)
Gain Loss On Sales Of Loans Net					(2)	5
Commercial Loans HFS transferred from portfolio in the current quarter
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Net impact related to fair value adjustments		(21)			(26)	(1)
Residential Mortgagel Loans Held For Sale
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Portfolio loans to loans held for sale						233
Net impact related to fair value adjustments						1
Other Real Estate Owned
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Net impact related to fair value adjustments		(3)	(1)		(7)	(6)
Nonrecurring Losses Included As Charge-Offs		2	$ 2		7	$ 10
Private Equity Investments
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
OTTI		$ 9			9
Residential Mortgage Loans
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Residential loans transferred to the Bancorp's portfolio				$ 55
Fair value adjustment				$ 1
Fair value of loans					$ 2		$ 2

[1] (a) Included in securities gains, net, in the Condensed Consolidated Statements of Income.