EARNINGS PER COMMON SHARE - Computation of Basic and Diluted Earnings Per Share (Details) (USD $) In Thousands, except Share data, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Numerator for basic and diluted earnings per share -income available to common shareholders:
Net income	$ 14,911	$ 16,242	$ 44,564	$ 51,038
Denominator for basic earnings per share - weighted average shares	57,201,390	57,976,943	57,309,934	57,902,102
Effect of dilutive securities -
Employee stock awards	698,194	842,833	725,862	905,210
Warrants	113,004	120,403	107,576	123,258
Denominator for diluted earnings per share - adjusted weighted average shares	58,012,588	58,940,179	58,143,372	58,930,570
Basic	$ 0.26	$ 0.28	$ 0.78	$ 0.88
Diluted	$ 0.26	$ 0.28	$ 0.77	$ 0.87