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, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Shareholders' Equity and Earnings Per Share Disclosure [Abstract]
Net income	$ 35,563	$ 32,302	$ 101,922	$ 81,107
Less: Preferred stock dividends and discount accretion	1,581	2,616	6,814	6,477
Net income applicable to common shares	33,982	29,686	95,108	74,630
Add: Dividends on convertible preferred stock, if dilutive	1,581	2,581	6,744	6,374
Net income applicable to common shares-Diluted	$ 35,563	$ 32,267	$ 101,852	$ 81,004
Weighted average common shares outstanding	39,331	36,381	37,939	36,305
Effect of dilutive potential common shares
Common stock equivalents	7,346	7,275	7,263	7,159
Convertible preferred stock, if dilutive	3,477	5,020	4,500	4,133
Total dilutive potential common shares	10,823	12,295	11,763	11,292
Average common shares and dilutive common shares	50,154	48,676	49,702	47,597
Net income per common share-Basic	$ 0.86	$ 0.82	$ 2.51	$ 2.06
Net income per common share-Diluted	$ 0.71	$ 0.66	$ 2.05	$ 1.70