EARNINGS PER COMMON SHARE - Computation of Basic and Diluted Earnings Per Share (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Numerator for basic and diluted earnings per share -income available to common shareholders:
Net income	$ 18,673	$ 15,344	$ 55,243	$ 46,401
Denominator for basic earnings per share - weighted average shares	61,135,749	59,403,109	61,088,794	57,907,203
Effect of dilutive securities -
Employee stock awards	715,585	576,543	643,536	594,082
Warrants	136,461	133,280	126,394	138,109
Denominator for diluted earnings per share - adjusted weighted average shares	61,987,795	60,112,932	61,858,724	58,639,394
Basic	$ 0.31	$ 0.26	$ 0.90	$ 0.80
Diluted	$ 0.30	$ 0.26	$ 0.89	$ 0.79