INCOME TAXES (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Current [Abstract]
Federal	$ 17,748	$ 16,096	$ 14,329
Foreign	1,080	1,441	1,287
State	1,104	131	1,906
Deferred [Abstract]
Federal	(332)	177	(803)
Foreign	148	127	183
State	91	1	(48)
Total income tax provision	19,839	17,973	16,854
Federal statutory rate (in hundredths)	35.00%
Income tax reconciliation [Abstract]
Income tax at Federal statutory rate	20,945	19,858	17,546
State income taxes, net of Federal income tax benefit	659	(207)	987
Other	(1,765)	(1,678)	(1,679)
Total income tax provision	19,839	17,973	16,854
Deferred tax assets [Abstract]
Inventories	435	396
Restricted stock and stock options	4,555	4,218
Other	696	773
Total deferred tax assets	5,686	5,387
Deferred tax liabilities [Abstract]
Customer list and goodwill amortization	2,567	2,952
Depreciation	6,981	6,471
Prepaid expense	665	574
Trade names and trademarks	157	157
Technology and trade secrets	176	176
Other	415	485
Total deferred tax liabilities	10,961	10,815
Net deferred tax liability	5,275	5,428
Unrecognized tax benefits [Roll Forward]
Balance, beginning of period	2,021	1,246	972
Increases for tax positions of prior years	116	397	97
Decreases for tax positions of prior years	(224)	(168)	(127)
Increases for tax positions related to current year	379	546	304
Balance, end of period	2,292	2,021	1,246
Interest and penalties	40	133	152
Accrued interest and penalties	$ 587	$ 547