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		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Earnings Per Share, Basic and Diluted, Other Disclosures [Abstract]
Net income	$ 38,355	$ 40,224	$ 121,238	$ 113,265
Less: Preferred stock dividends and discount accretion	4,079	1,581	7,240	4,743
Net income applicable to common shares—Basic	34,276	38,643	113,998	108,522
Add: Dividends on convertible preferred stock, if dilutive	1,579	1,581	4,740	4,743
Net income applicable to common shares—Diluted	$ 35,855	$ 40,224	$ 118,738	$ 113,265
Weighted average common shares outstanding	48,158	46,639	47,658	46,453
Effect of dilutive potential common shares
Common stock equivalents	978	1,166	1,070	1,274
Convertible preferred stock, if dilutive	3,071	3,075	3,071	3,075
Total dilutive potential common shares	4,049	4,241	4,141	4,349
Weighted average common shares and effect of dilutive potential common shares	52,207	50,880	51,799	50,802
Net income per common share-Basic	$ 0.71	$ 0.83	$ 2.39	$ 2.34
Net income per common share-Diluted	$ 0.69	$ 0.79	$ 2.29	$ 2.23