Consolidated Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Cash flows from operating activities:
Net loss	$ (66,400)	$ (154,677)	$ (50,424)
Adjustments to reconcile net loss to net cash used in operating activities:
Deferred income taxes	(696)	0	(9,635)
Bad debt expense	(235)	916	107
Depreciation and amortization	9,111	9,149	5,886
Stock-based compensation	11,644	12,286	9,255
Change in fair value of derivative liabilities	0	43,831	0
Change in fair value of contingent consideration related to acquisition	(2,900)	(2,500)	100
Accretion of interest & amortization of deferred financing costs on convertible notes	10,165	9,539	4,842
Accretion on marketable securities	0	(87)	59
Non-cash loss on debt extinguishment	3,997	0	0
Loss on disposal of assets	0	123	58
Non-cash foreign exchange (gain) loss	(678)	2,112	(504)
Changes in operating assets and liabilities:
Restricted cash	(607)	(2,001)	0
Accounts receivable and other receivables	4,771	(2,911)	(3,193)
Inventories	(3,035)	3,540	3,528
Prepaid expenses and other current assets	(1,034)	1,070	167
Accounts payable	(1,826)	(5,152)	8,342
Accrued payroll	(5,176)	7,079	(75)
Accrued expenses and other current liabilities	4,374	2,875	395
Net cash used in operating activities	(38,525)	(74,808)	(31,092)
Cash flows from investing activities:
Purchases of marketable securities	0	(20,976)	(82,646)
Maturity on marketable securities	21,000	55,850	89,690
Purchases of property and equipment	(1,170)	(2,796)	(4,191)
Acquisition of business, net of cash acquired of $24,012	0	(60,622)	0
Net cash provided by (used in) investing activities	19,830	(28,544)	2,853
Cash flows from financing activities:
Net proceeds from revolving line of credit	21	0	0
Deferred financing costs	(6,755)	(918)	(3,617)
Proceeds from sale of common stock under employee stock purchase plan	2,519	3,216	2,962
Proceeds from exercise of stock options	546	3,129	2,871
Proceeds from issuance of debt	120,000	0	125,000
Repayment of debt	(66,613)	0	0
Minimum tax withholding paid on behalf of employees for restricted stock units	0	(133)	(481)
Net cash provided by financing activities	49,718	5,294	126,735
Effect of exchange rate changes on cash and cash equivalents	848	(375)	(741)
Net increase (decrease) in cash and cash equivalents	31,871	(98,433)	97,755
Cash and cash equivalents, beginning of year	26,120	124,553	26,798
Cash and cash equivalents, end of year	57,991	26,120	124,553
Supplemental disclosure of cash flow information:
Cash paid for interest	9,836	6,262	1,957
Cash paid for income taxes	681	208	124
Non-cash investing and financing activities:
Landlord funded leasehold improvements	0	0	46
Fair value of warrants issued for business acquisition	0	44	0
Fair value of common stock issued for business acquisition	0	100,812	0
Acquisition of property and equipment included in accounts payable	0	0	155
Fair value of warrants issued in connection with the Facility Agreement	$ 14,704	$ 0	$ 0