ACCOUNTING POLICIES (Details 5) (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
Earnings (loss) per share
Net income (loss)	$ 8,787	$ 2,693	$ 470	$ 2,719	$ (3,409)	$ (7,787)	$ (7,798)	$ (444)	$ 14,669	$ (19,438)	$ 13,889
Deemed dividend related to redeemable common stock							(2)	(10)		(12)	(112)
Net income (loss) attributable to common shares	$ 8,787	$ 2,693	$ 470	$ 2,719	$ (3,409)	$ (7,787)	$ (7,800)	$ (454)	$ 14,669	$ (19,450)	$ 13,777
Net income (loss) per common share-basic:
Net income (loss) attributable to common shares-basic (in dollars per share)	$ (0.37)	$ (0.11)	$ (0.02)	$ (0.12)	$ 0.15	$ 0.33	$ 0.34	$ 0.02	$ 0.63	$ (0.84)	$ 0.60
Weighted average common shares outstanding-basic	23,450	23,447	23,437	23,392	23,278	23,276	23,265	23,215	23,387	23,259	23,019
Effect of dilutive securities:
Stock options and restricted stock awards (in shares)									285		347
Weighted average common shares outstanding-diluted	24,064	23,754	23,464	23,414	23,278	23,276	23,265	23,215	23,672	23,259	23,366
Net income (loss) attributable to common shares-diluted (in dollars per share)	$ (0.37)	$ (0.11)	$ (0.02)	$ (0.12)	$ 0.15	$ 0.33	$ 0.34	$ 0.02	$ 0.62	$ (0.84)	$ 0.59
Stock options and restricted stock awards
Anti-dilutive securities excluded from computation of earnings per share
Anti-dilutive securities excluded from computation of earnings per share (in shares)									537	927	551
Convertible senior notes
Anti-dilutive securities excluded from computation of earnings per share
Anti-dilutive securities excluded from computation of earnings per share (in shares)											454