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		9 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012	Sep. 30, 2011
Disclosure Shareholders Equity And Earnings Per Share Computation Of Basic And Diluted Earnings Per Common Share [Abstract]
Net income	$ 32,302	$ 30,202	$ 81,107	$ 58,354
Less: Preferred stock dividends and discount accretion	2,616	1,032	6,477	3,096
Net income applicable to common shares-Basic	29,686	29,170	74,630	55,258
Add: Dividends on convertible preferred stock, if dilutive	2,581	1,000	6,374	0
Net income applicable to common shares-Diluted	$ 32,267	$ 30,170	$ 81,004	$ 55,258
Weighted average common shares outstanding	36,381	35,550	36,305	35,152
Effect of dilutive potential common shares	12,295	10,551	11,292	8,683
Weighted average common shares and effect of dilutive potential common shares	48,676	46,101	47,597	43,835
Net income per common share - Basic	$ 0.82	$ 0.82	$ 2.06	$ 1.57
Net income per common share - Diluted	$ 0.66	$ 0.65	$ 1.70	$ 1.26