Number of Shares to be issued upon Exercise of Outstanding Stock-Based Awards and Remaining Shares Available for Future Issuance under all Equity Compensation Plans (Parenthetical) (Detail) (USD $)	1 Months Ended
	Apr. 30, 2009	Mar. 31, 2007	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009	Dec. 31, 2008
Employee Stock Ownership Plan (ESOP) Disclosures [Line Items]
Weighted-average exercise price of the outstanding options			$ 53.88	$ 52.01	$ 49.29	$ 48.97
Number of shares to be issued based on predefined performance targets			11,326,000
Additional shares approved by shareholders included under Bancorp's 1993 Stock Purchase Plan	12,000,000	1,500,000
Performance Incentive Plan 2008 [Member]
Employee Stock Ownership Plan (ESOP) Disclosures [Line Items]
Stock authorized for issuance			4,500,000
Acquisition [Member]
Employee Stock Ownership Plan (ESOP) Disclosures [Line Items]
Outstanding options awarded in connection with mergers and acquisitions			1,000,000
Weighted-average exercise price of the outstanding options			$ 16.31
Number of shares to be issued based on predefined performance targets			1,500,000
2011 Incentive Compensation Plan
Employee Stock Ownership Plan (ESOP) Disclosures [Line Items]
Stock authorized for issuance			39,000,000