NET INCOME PER COMMON 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
NET INCOME PER COMMON SHARE
Net income	$ 12,619	$ 14,079	$ 18,616	$ 23,569
Shares of common stock outstanding used to compute basic per common share amounts	35,469,769	34,849,659	35,319,944	34,724,077
Effect of dilutive restricted stock and options (in shares)	121,995	458,038	150,226	501,794
Shares used to compute dilutive per common share amounts	35,591,764	35,307,697	35,470,170	35,225,871
Basic income per share (in dollars per share)	$ 0.36	$ 0.40	$ 0.53	$ 0.68
Diluted income per share (in dollars per share)	$ 0.35	$ 0.40	$ 0.52	$ 0.67