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, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Earnings Per Share, Basic and Diluted, Other Disclosures [Abstract]
Net income	$ 53,115	$ 38,355	$ 152,267	$ 121,238
Less: Preferred stock dividends and discount accretion	3,628	4,079	10,884	7,240
Net income applicable to common shares	49,487	34,276	141,383	113,998
Add: Dividends on convertible preferred stock, if dilutive	1,578	1,579	4,735	4,740
Net income applicable to common shares—Diluted	$ 51,065	$ 35,855	$ 146,118	$ 118,738
Weighted average common shares outstanding	51,679	48,158	49,763	47,658
Effect of dilutive potential common shares
Common stock equivalents	938	978	822	1,070
Convertible preferred stock, if dilutive	3,109	3,071	3,109	3,071
Total dilutive potential common shares	4,047	4,049	3,931	4,141
Weighted average common shares and effect of dilutive potential common shares	55,726	52,207	53,694	51,799
Net income per common share-Basic (usd per share)	$ 0.96	$ 0.71	$ 2.84	$ 2.39
Net income per common share-Diluted (usd per share)	$ 0.92	$ 0.69	$ 2.72	$ 2.29