Unaudited Consolidated Statements of Comprehensive Loss - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Statement of Comprehensive Income [Abstract]
Net loss	$ (24,488)	$ (12,683)	$ (47,127)	$ (27,729)
Other comprehensive income (loss):
Unrealized income on marketable securities, net of tax	31	27	50	18
Gains (losses) on marketable securities reclassified into earnings, net of tax	3	(8)	(6)	(7)
Total	34	19	44	11
Unrealized income (loss) on derivative instruments, net of tax	832	(1,832)	3,316	(3,885)
Losses on derivative instruments reclassified into earnings, net of tax	80	948	531	900
Total	912	(884)	3,847	(2,985)
Total other comprehensive income (loss)	946	(865)	3,891	(2,974)
Comprehensive loss	$ (23,542)	$ (13,548)	$ (43,236)	$ (30,703)