NET INCOME PER SHARE - Calculation of net income per share (Details) (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2011	Sep. 30, 2011	Jun. 30, 2011	Mar. 31, 2011	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Net income:
Income from continuing operations	$ 5,954	$ 10,080	$ 54,776	$ 1,125	$ 1,261	$ 1,601	$ (207)	$ 736	$ 71,934	$ 3,393	$ 669
Income (loss) from discontinued operations	12	217	150	(7)	(302)	(317)	(60)	(146)	373	(826)	(489)
Net income	$ 5,966	$ 10,297	$ 54,926	$ 1,118	$ 959	$ 1,284	$ (267)	$ 590	$ 72,307	$ 2,567	$ 180
Shares outstanding:
Weighted-average common shares outstanding									21,814	20,534	19,971
Additional dilutive common stock equivalents									257	201	211
Diluted shares outstanding									22,071	20,735	20,182
Basic net income per share:
Basic net income per share from continuing operations (in dollars per share)									$ 3.30	$ 0.16	$ 0.03
Basic net income (loss) per share from discontinued operations (in dollars per share)									$ 0.02	$ (0.04)	$ (0.02)
Basic net income per share	$ 0.27	$ 0.46	$ 2.52	$ 0.05	$ 0.05	$ 0.06	$ (0.01)	$ 0.03	$ 3.32	$ 0.12	$ 0.01
Diluted net income per share:
Diluted net income per share from continuing operations (in dollars per share)									$ 3.26	$ 0.16	$ 0.03
Diluted net income (loss) per share from discontinued operations (in dollars per share)									$ 0.02	$ (0.04)	$ (0.02)
Diluted net income per share	$ 0.27	$ 0.46	$ 2.49	$ 0.05	$ 0.05	$ 0.06	$ (0.01)	$ 0.03	$ 3.28	$ 0.12	$ 0.01