Shareholders' Equity And Earnings Per Share (Computation Of Basic And Diluted Earnings Per Common Share) (Detail) (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended
	Mar. 31, 2015	Mar. 31, 2014
Earnings Per Share, Basic and Diluted, Other Disclosures [Abstract]
Net income	$ 39,052	$ 34,500
Less: Preferred stock dividends and discount accretion	1,581	1,581
Net income applicable to common shares—Basic	37,471	32,919
Add: Dividends on convertible preferred stock, if dilutive	1,581	1,581
Net income applicable to common shares—Diluted	$ 39,052	$ 34,500
Weighted average common shares outstanding	47,239	46,195
Effect of dilutive potential common shares
Common stock equivalents	1,158	1,434
Convertible preferred stock, if dilutive	3,075	3,075
Total dilutive potential common shares	4,233	4,509
Weighted average common shares and effect of dilutive potential common shares	51,472	50,704
Net income per common share-Basic	$ 0.79	$ 0.71
Net income per common share-Diluted	$ 0.76	$ 0.68