VALUATION AND QUALIFYING ACCOUNTS - Summary of valuation and qualifying accounts (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2012		Dec. 31, 2011		Dec. 31, 2010
Allowance for doubtful accounts receivable
Movement in Valuation Allowances and Reserves [Roll Forward]
Valuation allowances and reserves, Balance at beginning of period	$ 2,757		$ 2,413		$ 384
Charged to costs and expenses	80		348		2,060
Charged to other accounts
Deductions	2,245	[1]	4	[1]	31	[1]
Valuation allowances and reserves, Balance at end of period	592		2,757		2,413
Allowance for obsolete inventory
Movement in Valuation Allowances and Reserves [Roll Forward]
Valuation allowances and reserves, Balance at beginning of period	617		569		670
Charged to costs and expenses	323		89
Charged to other accounts
Deductions	192	[2]	41	[2]	83	[2]
Reduction in allowance for obsolete inventory amounts					18	[3]
Valuation allowances and reserves, Balance at end of period	$ 748		$ 617		$ 569

[1] write-off of uncollectible amounts

[2] disposal of inventory

[3] reduction in allowance for obsolete inventory amounts