Condensed Consolidated Statements of Cash Flows (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2015	Mar. 31, 2014
Cash flows from operating activities:
Net income (loss)	$ (11,213)	$ 5,295
Adjustments to reconcile net income (loss) to net cash used in operating activities:
Depreciation and amortization	1,489	602
Stock-based compensation	2,211	1,613
Change in fair value of contingent consideration related to acquisition	100	(11,800)
Accretion of interest on convertible note	863	800
Amortization of deferred financing costs	113	97
Non-cash foreign exchange loss (gain)	111	(367)
Changes in operating assets and liabilities:
Accounts receivable and other receivables	48	(254)
Inventories	(4,637)	(4,360)
Prepaid expenses and other current assets	681	(147)
Accounts payable	859	4,005
Accrued payroll	(2,482)	(1,654)
Accrued expenses and other liabilities	130	3,190
Net cash used in operating activities	(11,727)	(2,980)
Cash flows from investing activities:
Purchases of marketable securities	(28,059)	(53,023)
Maturities of marketable securities	34,430	6,918
Purchases of property and equipment	(2,174)	(3,491)
Net cash provided by (used in) investing activities	4,197	(49,596)
Cash flows from financing activities:
Proceeds from exercise of stock options	1,642	246
Minimum tax withholding paid on behalf of employees for restricted stock units	(35)	(644)
Net cash provided by (used in) financing activities	1,607	(398)
Effect of exchange rate changes on cash and cash equivalents	(692)	1
Net decrease in cash and cash equivalents	(6,615)	(52,973)
Cash and cash equivalents, beginning of period	26,798	95,152
Cash and cash equivalents, end of period	20,183	42,179
Supplemental disclosure of cash flow information:
Cash paid for income taxes	35	129
Non-cash investing and financing activities:
Landlord funded leasehold improvements	0	2,425
Acquisition of property and equipment included in accounts payable	$ 1,254	$ 0