Condensed Consolidated Statements of Operations - USD ($) shares in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Revenue	$ 199,870,000	$ 102,894,000	$ 361,913,000	$ 193,190,000
Cost of sales	51,563,000	26,888,000	94,815,000	49,802,000
Gross margin	148,307,000	76,006,000	267,098,000	143,388,000
Operating expenses:
Research and development	30,203,000	14,712,000	62,219,000	29,647,000
General and administrative	63,734,000	39,565,000	127,764,000	75,132,000
Sales and marketing	88,190,000	54,431,000	179,129,000	107,839,000
Total operating expenses	182,127,000	108,708,000	369,112,000	212,618,000
Loss from operations	(33,820,000)	(32,702,000)	(102,014,000)	(69,230,000)
Other income (expense)
Investment income	7,669,000	4,917,000	14,324,000	8,590,000
Interest expense	(12,712,000)	(8,603,000)	(34,702,000)	(15,113,000)
Total other expense	(5,043,000)	(3,686,000)	(20,378,000)	(6,523,000)
Net loss before tax	(38,863,000)	(36,388,000)	(122,392,000)	(75,753,000)
Income tax benefit (expense)	443,000	1,000	913,000	(58,000)
Net loss	$ (38,420,000)	$ (36,387,000)	$ (121,479,000)	$ (75,811,000)
Net loss per share-basic and diluted (in dollars per share)	$ (0.30)	$ (0.30)	$ (0.95)	$ (0.62)
Weighted average common shares outstanding-basic and diluted (in shares)	129,182	122,129	127,723	121,578