Consolidated Statements of Cash Flows - Debt Instrument, Name [Domain] - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014
Cash flows from operating activities
Net loss	$ (27,266)	$ (35,255)
Adjustments to reconcile net loss to net cash used in operating activities
Depreciation and amortization	7,114	6,100
Non-cash interest and other expense	3,789	5,869
Stock-based compensation expense	9,630	8,577
Loss on extinguishment of debt	0	18,943
Provision for bad debts	1,180	1,804
Changes in operating assets and liabilities:
Accounts receivable	6,876	(10,534)
Inventories	(10,336)	699
Deferred revenue	534	355
Prepaid expenses and other assets	632	(1,006)
Accounts payable, accrued expenses and other current liabilities	4,997	4,361
Other long-term liabilities	147	(422)
Net cash used in operating activities	(2,703)	(509)
Cash flows from investing activities
Purchases of property and equipment	(4,601)	(5,745)
Net cash used in investing activities	(4,601)	(5,745)
Cash flows from financing activities
Principal payments of capital lease obligations	(2,814)	(1,262)
Proceeds from Issuance of long-term debt, net of issuance costs	0	194,570
Repayments of Convertible Debt	0	160,685
Proceeds from issuance of common stock, net of offering costs	6,489	5,339
Payment of withholding taxes in connection with vesting of restricted stock units	(2,427)	(5,890)
Net cash provided by financing activities	1,248	32,072
Net (decrease) increase in cash and cash equivalents	(6,056)	25,818
Cash and cash equivalents, beginning of period	151,193	149,727
Cash and cash equivalents, end of period	145,137	175,545
Allocation to equity for conversion for the 2% Notes	0	35,638
Purchases of property and equipment under capital lease	$ 5,721	$ 0