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		6 Months Ended
	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013
Numerator for basic and diluted earnings per share -income available to common shareholders:
Net income	$ 15,953	$ 15,829	$ 31,057	$ 29,653
Denominator for basic earnings per share - weighted average shares	57,201,494	57,291,994	57,146,853	57,365,105
Effect of dilutive securities -
Employee stock awards	613,919	735,440	602,863	739,927
Warrants	136,223	100,915	140,552	101,471
Denominator for diluted earnings per share - adjusted weighted average shares	57,951,636	58,128,349	57,890,268	58,206,503
Basic	$ 0.28	$ 0.28	$ 0.54	$ 0.52
Diluted	$ 0.28	$ 0.27	$ 0.54	$ 0.51