CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018
Cash flows from operating activities:
Net income (loss)	$ 44,482	$ (12,336)
Adjustments to reconcile net income (loss) to net cash provided by operating activities:
Depreciation and amortization	11,551	6,950
Provision for doubtful accounts	408	668
Asset impairment	0	1,636
Non-cash interest expense	4,173	1,880
Financing fees on extinguishment of debt	2,152	0
Fees paid for repurchase and exchange of convertible notes due 2023	6,000	0
Stock-based compensation	14,000	9,911
Changes in operating assets and liabilities:
Accounts receivable	(56,139)	10,671
Inventory	(13,964)	8,112
Prepaid expenses and other assets	(8,634)	(3,995)
Intangible assets	0	(6,000)
Accounts payable, accrued and other liabilities	18,656	4,672
Warranty obligations	3,330	2,368
Deferred revenues	10,781	(10,280)
Net cash provided by operating activities	36,796	14,257
Cash flows from investing activities:
Purchases of property and equipment	(7,368)	(2,384)
Acquisition	0	(9,000)
Net cash used in investing activities	(7,368)	(11,384)
Cash flows from financing activities:
Issuance of convertible notes due 2024, net of issuance costs	127,481	0
Purchase of convertible note hedges	(36,313)	0
Sale of warrants	29,819	0
Fees paid for repurchase and exchange of convertible notes due 2023	(6,000)	0
Principal payments and financing fees on debt	(45,658)	(5,664)
Proceeds from issuance of common stock, net of issuance costs	0	19,771
Proceeds from debt, net of issuance costs	0	68,352
Proceeds from exercise of equity awards	2,925	2,151
Payment of withholding taxes related to net share settlement of equity awards	(4,438)	0
Net cash provided by financing activities	67,816	84,610
Effect of exchange rate changes on cash	(435)	(463)
Net increase in cash and cash equivalents	96,809	87,020
Cash and cash equivalents—Beginning of period	106,237	29,144
Cash and cash equivalents—End of period	203,046	116,164
Supplemental disclosures of non-cash investing and financing activities:
Acquisition funded by issuance of common stock	0	19,219
Acquisition funded by accrued liabilities	0	6,000
Purchases of fixed assets included in accounts payable	926	125
Accrued interest payable unpaid upon exchange of convertible notes due 2023	$ 833	$ 0