EARNINGS PER COMMON SHARE - Computation of Basic and Diluted Earnings Per Share (Detail) (USD $) In Thousands, except Share data, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2012	Jun. 30, 2011	Jun. 30, 2012	Jun. 30, 2011
Numerator for basic and diluted earnings per share -income available to common shareholders:
Net income	$ 17,802	$ 15,973	$ 34,796	$ 33,180
Dividends on preferred stock	0	0	0	0
Income available to common shareholders	$ 17,802	$ 15,973	$ 34,796	$ 33,180
Denominator for basic earnings per share - weighted average shares	57,933,281	57,694,792	57,864,269	57,642,970
Effect of dilutive securities -
Employee stock awards	915,301	945,250	936,550	974,958
Warrants	109,697	94,620	120,870	104,520
Denominator for diluted earnings per share - adjusted weighted average shares	58,958,279	58,734,662	58,921,689	58,722,448
Earnings per share available to common shareholders
Basic	$ 0.31	$ 0.28	$ 0.60	$ 0.58
Diluted	$ 0.30	$ 0.27	$ 0.59	$ 0.57