NET INCOME PER COMMON SHARE (Details) (USD $) In Thousands, except Share data, unless otherwise specified	3 Months Ended
	Mar. 31, 2013	Mar. 31, 2012
NET INCOME PER COMMON SHARE
Net income	$ 9,490	$ 8,636
Shares of common stock outstanding used to compute basic per common share amounts	34,598,494	34,036,539
Effect of dilutive restricted stock and options (in shares)	467,538	603,121
Shares used to compute diluted per common share amounts	35,066,032	34,639,660
Basic income per share (in dollars per share)	$ 0.27	$ 0.25
Diluted income per share (in dollars per share)	$ 0.27	$ 0.25
Anti-dilutive options (in shares)	0	0