INCOME TAXES - Summary of temporary differences (Details 1) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Deferred tax assets:
Goodwill and intangible assets	$ 2,928	$ 1,669
Inventories	436	451
Non-deductible accruals and allowances	482	1,428
Net operating loss carryforwards	192	180
Asset retirement obligation	321	299
Share-based compensation	358	207
Tax credit carryforwards	139	205
Capital loss carryforwards	117	121
Other	38	76
Gross deferred tax assets	5,011	4,636
Deferred tax liabilities:
Property and equipment	(2,937)	(3,311)
Other	(13)
Gross deferred tax liabilities	(2,950)	(3,311)
Valuation allowance	(336)	(340)	(166)	(148)
Net deferred tax asset	$ 1,725	$ 985