CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	3 Months Ended		12 Months Ended
	Mar. 31, 2020	Mar. 31, 2019	Dec. 31, 2019	Mar. 31, 2020	Dec. 31, 2019	Mar. 31, 2019
Cash flows from operating activities:
Net income	$ 68,936	$ 2,765
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	3,844	3,572
Provision for doubtful accounts	104	0	$ 217
Non-cash interest expense	2,722	1,490
Financing fees on extinguishment of debt	0	2,152
Stock-based compensation	7,515	3,290
Change in fair value of derivatives	(15,344)	0
Deferred income taxes	(12,500)	0
Changes in operating assets and liabilities:
Accounts receivable	49,637	(3,266)
Inventory	(2,560)	3,296
Prepaid expenses and other assets	(5,009)	(2,413)
Accounts payable, accrued and other liabilities	(22,066)	4,851
Warranty obligations	403	(252)
Deferred revenues	(36,460)	1,578
Net cash provided by operating activities	39,222	17,063
Cash flows from investing activities:
Purchases of property and equipment	(3,353)	(658)
Net cash used in investing activities	(3,353)	(658)
Cash flows from financing activities:
Issuance of convertible notes, net of issuance costs	313,011	0
Purchase of convertible note hedges	(89,056)	0
Sale of warrants	71,552	0
Principal payments and financing fees on debt	(1,148)	(44,731)
Proceeds from exercise of equity awards and employee stock purchase plan	1,979	1,664
Payment of withholding taxes related to net share settlement of equity awards	(34,267)	(1,355)
Net cash provided by (used in) financing activities	262,071	(44,422)
Effect of exchange rate changes on cash and cash equivalents	(205)	(133)
Net increase (decrease) in cash, cash equivalents, and restricted cash	297,735	(28,150)
Cash, cash equivalents and restricted cash—Beginning of period	296,109	106,237	106,237
Cash, cash equivalents and restricted cash—End of period	593,844	78,087	296,109
Reconciliation of cash, cash equivalents, and restricted cash to the condensed consolidated balance sheets
Cash and cash equivalents				$ 549,144	$ 251,409	$ 78,087
Restricted cash				44,700	44,700	0
Total cash, cash equivalents, and restricted cash	593,844	78,087	$ 106,237	$ 593,844	$ 296,109	$ 78,087
Supplemental disclosures of non-cash investing and financing activities:
Purchases of fixed assets included in accounts payable	585	458
Convertible senior note issuance costs included in accounts payable and accrued expense	$ 591	$ 0