Income Taxes - Components of Deferred Tax Assets and Liabilities (Detail) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Schedule Of Deferred Tax Assets And Liabilities [Line Items]
Deferred rent	$ 508	$ 623
Accrued vacation	2,480	1,926
Accrued bonus	2,747	4,342
Deferred compensation	1,497	1,451
Inventory items	6,967	7,072
Allowance for doubtful accounts and other receivables	211	355
Other accruals	6,531	7,355
Equity based compensation expense	16,620	16,124
Unrealized gain on securities	438	288
Unrealized loss on other investments	419	0
Net operating loss carry-forwards	2,462	4,511
Valuation allowance	(267)	(267)	(267)	0
Total deferred tax assets	40,613	43,780
Unrealized loss on other investments	0	(931)
Depreciation and amortization	(24,527)	(17,052)
Total deferred tax liabilities	(24,527)	(17,983)
Net deferred tax assets	$ 16,086	$ 25,797