Stock-Based Compensation (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) - shares shares in Thousands	12 Months Ended
	Dec. 31, 2009	Dec. 31, 2007	Dec. 31, 2018	Dec. 31, 2017
Employee Stock Ownership Plan (ESOP) Disclosures
Number of shares to be issued based on predefined performance targets			8,888
Additional shares approved by shareholders included under Bancorp's 1993 Stock Purchase Plan	12,000	1,500
Performance Share Awards
Employee Stock Ownership Plan (ESOP) Disclosures
Number of shares to be issued based on predefined performance targets			2,000
2017 Incentive Compensation Plan
Employee Stock Ownership Plan (ESOP) Disclosures
Stock authorized for issuance				6,000