CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Cash flows from operating activities:
Net income (loss)	$ 161,148	$ (11,627)	$ (45,192)
Adjustments to reconcile net income (loss) to net cash provided by operating activities:
Depreciation and amortization	14,119	9,667	9,004
Provision for doubtful accounts	217	711	476
Asset impairment	1,124	1,601	1,681
Non-cash interest expense	6,081	2,701	1,673
Financing fees on extinguishment of debt	2,152	0	0
Fees paid for repurchase and exchange of convertible notes due 2023	6,000	0	0
Stock-based compensation	20,176	11,432	6,727
Deferred income taxes	(73,375)	123	(1,394)
Changes in operating assets and liabilities:
Accounts receivable	(68,745)	(13,515)	(4,803)
Inventory	(15,789)	9,732	5,961
Prepaid expenses and other assets	(14,293)	(3,130)	(1,227)
Intangible assets	0	(10,000)	0
Accounts payable, accrued and other liabilities	22,200	23,082	(5,078)
Warranty obligations	5,804	1,478	(1,598)
Deferred revenues	72,248	(6,123)	5,328
Net cash provided by (used in) operating activities	139,067	16,132	(28,442)
Cash flows from investing activities:
Purchases of property and equipment	(14,788)	(4,151)	(4,121)
Acquisition	0	(15,000)	0
Net cash used in investing activities	(14,788)	(19,151)	(4,121)
Cash flows from financing activities:
Issuance of convertible notes due 2024, net of issuance costs	127,413	0	0
Purchase of convertible note hedges	(36,313)	0	0
Sale of warrants	29,818	0	0
Fees paid for repurchase and exchange of convertible notes due 2023	(6,000)	0	0
Principal payments and financing fees on debt	(45,855)	(9,976)	0
Proceeds from issuance of common stock, net of issuance costs	0	19,766	26,425
Proceeds from debt, net of issuance costs	0	68,024	26,442
Payments under revolving credit facility	0	0	(10,100)
Proceeds from exercise of equity awards and employee stock purchase plan	4,985	2,800	530
Payment of withholding taxes related to net share settlement of equity awards	(8,198)	0	0
Net cash provided by financing activities	65,850	80,614	43,297
Effect of exchange rate changes on cash and cash equivalents	(257)	(502)	646
Net increase in cash, cash equivalents, and restricted cash	189,872	77,093	11,380
Cash, cash equivalents and restricted cash—Beginning of period	106,237	29,144	17,764
Cash, cash equivalents and restricted cash—End of period	296,109	106,237	29,144
Reconciliation of cash, cash equivalents, and restricted cash to the consolidated balance sheets
Total cash, cash equivalents, and restricted cash	296,109	29,144	17,764
Supplemental cash flow disclosure:
Cash paid for interest	2,689	6,343	5,816
Cash paid for income taxes	1,755	775	909
Supplemental disclosures of non-cash investing and financing activities:
Acquisition funded by issuance of common stock	0	19,219	0
Purchases of fixed assets included in accounts payable	672	895	551
Accrued interest payable unpaid upon exchange of convertible notes due 2023	$ 833	$ 0	$ 0