Deferred Tax Assets and liabilities (Detail) (USD $)	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Schedule Of Deferred Tax Assets [Line Items]
Deferred Compensation	$ 0	$ 301,000	$ 314,000
Reserves on inventory and sales	336,000	242,000	140,000
Credit and loss carryforwards	692,000	545,000	178,000
Stock compensation	0	0	601,000
Other	690,000	516,000	77,000
Inventory Capitalization	526,000	555,000	0
Sales tax accrual	1,228,000	0	0
Total deferred tax assets	3,472,000	2,159,000	1,310,000
Unrealized gain/loss on investments	(333,000)	(250,000)	(145,000)
Prepaid expenses	(752,000)	(426,000)	(429,000)
Depreciation	(7,729,000)	(8,075,000)	(1,317,000)
Stock compensation	(105,000)	(109,000)	0
Total deferred tax liabilities	(8,919,000)	(8,860,000)	(1,891,000)
Net deferred tax liabilities	$ (5,447,000)	$ (6,701,000)	$ (581,000)