Shareholders' Equity And Earnings Per Share (Computation Of Basic And Diluted Earnings Per Common Share) (Detail) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Earnings Per Share, Basic and Diluted, Other Disclosures [Abstract]
Net income	$ 49,111	$ 39,052
Less: Preferred stock dividends and discount accretion	3,628	1,581
Net income applicable to common shares—Basic	45,483	37,471
Add: Dividends on convertible preferred stock, if dilutive	1,578	1,581
Net income applicable to common shares—Diluted	$ 47,061	$ 39,052
Weighted average common shares outstanding	48,448	47,239
Effect of dilutive potential common shares
Common stock equivalents	750	1,158
Convertible preferred stock, if dilutive	3,070	3,075
Total dilutive potential common shares	3,820	4,233
Weighted average common shares and effect of dilutive potential common shares	52,268	51,472
Net income per common share-Basic	$ 0.94	$ 0.79
Net income per common share-Diluted	$ 0.90	$ 0.76