CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE LOSS - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Statement of Comprehensive Income [Abstract]
Net loss	$ (13,244)	$ (121,169)	$ (35,952)	$ (243,569)
Other comprehensive loss:
Holding (losses) gains associated with marketable securities arising during period, net of tax	823	344	275	953
Total comprehensive loss	$ (12,421)	$ (120,825)	$ (35,677)	$ (242,616)