Common, Preferred, and Treasury Stock - Additional Information (Detail) (USD $) In Millions, except Share data, unless otherwise specified	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2008	Dec. 31, 2012
Issuance of preferred shares	$ 297	$ 1,034
Series J Preferred Stock
Depositary shares	300,000
Preferred stock, issued	12,000
Issuance of preferred shares	297
Preferred stock, liquidation preference	$ 25,000
Preferred Stock, Dividend Payment Terms	The preferred stock accrues dividends, on a non-cumulative semi-annual basis, at an annual rate of 4.90% through but excluding September 30, 2019, at which time it converts to a quarterly floating rate dividend of three-month LIBOR plus 3.129%.
Preferred Stock, Redemption Terms	Subject to any required regulatory approval, the Bancorp may redeem the Series J preferred shares at its option, in whole or in part, at any time on or after September 30, 2019, or any time prior following a regulatory capital event
Preferred stock, shares authorized	12,000
Series I Preferred Stock
Depositary shares		18,000,000
Preferred stock, issued	18,000	18,000
Issuance of preferred shares		441
Preferred stock, liquidation preference	$ 25,000	$ 25,000
Preferred Stock, Dividend Payment Terms	The preferred stock accrues dividends, on a non-cumulative quarterly basis, at an annual rate of 6.625% through but excluding December 31, 2023, at which time it converts to a quarterly floating rate dividend of three-month LIBOR plus 3.71%
Preferred Stock, Redemption Terms	Subject to any required regulatory approval, the Bancorp may redeem the Series I preferred shares at its option in whole or in part, at any time on or after December 31, 2023 and may redeem in whole but not in part, following a regulatory capital event at any time prior to December 31, 2023
Preferred stock, shares authorized	18,000	18,000
Series H Preferred Stock
Depositary shares		600,000
Preferred stock, issued	24,000	24,000
Issuance of preferred shares		593
Preferred stock, liquidation preference	$ 25,000	$ 25,000
Preferred Stock, Dividend Payment Terms	The preferred stock accrues dividends, on a non-cumulative semi-annual basis, at an annual rate of 5.10% through but excluding June 30, 2023, at which time it converts to a quarterly floating rate dividend of three-month LIBOR plus 3.033%
Preferred Stock, Redemption Terms	Subject to any required regulatory approval, the Bancorp may redeem the Series H preferred shares at its option in whole or in part, at any time on or after June 30, 2023 and may redeem in whole but not in part, following a regulatory capital event at any time prior to June 30, 2023
Preferred stock, shares authorized	24,000	24,000
Series G Preferred Stock
Depositary shares		4,110,500
Preferred stock, liquidation preference			$ 25,000
Preferred Stock, Redemption Terms	The preferred stock was convertible at any time, at the option of the shareholder, into 2,159.8272 shares of common stock, representing a conversion price of approximately $11.575 per share of common stock. On June 11, 2013, pursuant to the Amended Articles of Incorporation, the Bancorp’s Board of Directors authorized the conversion into common stock, no par value, of all outstanding shares of the Bancorp’s Series G perpetual preferred stock. The Articles grant the Bancorp the right, at its option, to convert all outstanding shares of Series G preferred stock if the closing price of common stock exceeded 130% of the applicable conversion price for 20 trading days within any period of 30 consecutive trading days. The closing price of shares of common stock satisfied such threshold for the 30 trading days ended June 10, 2013, and the Bancorp gave the required notice of its exercise of its conversion right. On July 1, 2013, the Bancorp converted the remaining 16,442 outstanding shares of Series G preferred stock, which represented 4,110,500 depositary shares, into shares of Fifth Third’s common stock. Each share of Series G preferred stock was converted into 2,159.8272 shares of common stock, representing a total of 35,511,740 issued shares. The common shares issued in the conversion are exempt securities pursuant to Section 3(a)(9) of the Securities Act of 1933, as amended, as the securities exchanged were exclusively with the Bancorp’s existing security holders where no commission or other remuneration was paid. Upon conversion, the depositary shares were delisted from the NASDAQ Global Select Market and withdrawn from the Exchange.
Preferred stock, convertible into shares of common stock			2,159.8272
Preferred stock, conversion price per share of common stock			$ 11.575
August 2012 Repurchase Program
Stock Repurchase Authorization Amount				600
Repurchase Shares Authorized				100
March 2013 Repurchase Program
Stock Repurchase Authorization Amount		984
Repurchase Shares Authorized		100
March 2014 Repurchase Program
Stock Repurchase Authorization Amount	$ 669
Repurchase Shares Authorized	100
Common stock issued after preferred Series G converstion
Issuance of stock		35,511,740
Preferred Stock | Series J Preferred Stock
Issuance of stock	12,000
Preferred Stock | Series I Preferred Stock
Issuance of stock		18,000
Preferred Stock | Series H Preferred Stock
Issuance of stock		24,000