Stock-Based Compensation - Additional Information (Detail) (USD $) In Millions, except Share data, unless otherwise specified	12 Months Ended
	Dec. 31, 2014		Dec. 31, 2013	Dec. 31, 2012
Employee Stock Ownership Plan (ESOP) Disclosures [Line Items]
Shares available for future issuance	38,217,000
The Bancorp's total overhang (potential dilution from share-based compensation)	10.00%
Stock options, SARs, restricted stock and performance units outstanding as a percentage of issued shares	7.00%
Stock-based compensation expense	$ 83		$ 78	$ 69
Tax benefit for stock-based compensation expense	30		28	24
Weighted-average grant-date fair value per share	$ 6.53		$ 4.56	$ 4.23
Incentive Compensation Plan 2014
Employee Stock Ownership Plan (ESOP) Disclosures [Line Items]
Shares available for future issuance	36,000,000
Full value awards
Employee Stock Ownership Plan (ESOP) Disclosures [Line Items]
Shares available for future issuance	16,000,000
Stock Appreciation Rights
Employee Stock Ownership Plan (ESOP) Disclosures [Line Items]
Vesting period of share based compensation	four year period
Stock-based compensation expense	57
Weighted-average grant-date fair value per share	$ 21.63		$ 16.16	$ 14.36
Total grant-date fair value	34		29	22
Weighted-average period over which expense is expected to be recognized	2 years 4 months 24 days
Shares granted	4,526,000		10,267,000	12,179,000
Exercisable Weighted-Average Remaining Contractual Life	4 years 3 months 18 days
Restricted Stock
Employee Stock Ownership Plan (ESOP) Disclosures [Line Items]
Vesting period of share based compensation	vest after four years, or ratably over three or four years of continued employment
Stock-based compensation expense	88
Weighted-average grant-date fair value per share	$ 21.61		$ 16.21	$ 14.33
Total grant-date fair value	32		40	32
Weighted-average period over which expense is expected to be recognized	2 years 7 months 6 days
Shares granted	3,264,000		3,583,000	3,863,000
Phantom Stock Units
Employee Stock Ownership Plan (ESOP) Disclosures [Line Items]
Settled phantom stock units			200,130	199,813
Settlement terms of phantom stock units	Phantom stock units issued on or before June 12, 2010 were settled in cash upon the earlier to occur of June 15, 2011 or the executive’s death. Units issued thereafter were settled in cash with 50% settled on June 15, 2012 and 50% settled on June 15, 2013. The amount paid on settlement of the phantom stock units was equal to the total amount of phantom stock units settled at the reported closing price of the Bancorp’s common stock on the settlement date.
Performance Units
Employee Stock Ownership Plan (ESOP) Disclosures [Line Items]
Vesting period of share based compensation	three-year cliff vesting terms
Weighted-average grant-date fair value per share	$ 15.61		$ 16.15	$ 14.36
Shares granted	322,567		348,595	344,741
Stock Option
Employee Stock Ownership Plan (ESOP) Disclosures [Line Items]
Intrinsic Value of Options Exercised	1		1	1
Cash received from options exercised	1		2	2
Aggregate intrinsic value of exercisable options	2
Employee stock purchase plan
Employee Stock Ownership Plan (ESOP) Disclosures [Line Items]
Shares available for future issuance	7,431,000	[1]
Stock-based compensation expense	$ 1		$ 1	$ 1
Match on qualifying employees purchase of shares of the Bancorp's common stock	15.00%
Stock purchased by plan participants	599,101		690,039	827,709

[1] Represents remaining shares of Fifth Third common stock under the Bancorp’s 1993 Stock Purchase Plan, as amended and restated, including an additional 1.5 million shares approved by shareholders on March 28, 2007 and an additional 12 million shares approved by shareholders on April 21, 2009.