UNAUDITED CONDENSED CONSOLIDATED STATEMENTS OF OPERATIONS - USD ($) shares in Thousands, $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Income Statement [Abstract]
Revenue	$ 11,770	$ 19,416
Costs and expenses:
Operating expenses (excluding depreciation and amortization)	13,801	22,841
Corporate general and administrative	4,361	4,493
Depreciation and amortization	307	2,191
Research and development	1,542	2,555
Loss (gain) on disposal of long-lived assets	2	(33)
Impairment of fixed, long-lived and intangible assets	0	57,454
Total costs and expenses	20,013	89,501
Loss from operations	(8,243)	(70,085)
Other (expense) income:
Interest expense	(18)	(4)
Other expense, net	(33)	(47)
Total other (expense) income, net	(51)	(51)
Loss before income taxes	(8,294)	(70,136)
Income tax (expense) benefit	(6)	6,169
Net loss	$ (8,300)	$ (63,967)
Loss per common share:
Basic (in dollars per share)	$ (0.12)	$ (1.07)
Diluted (in dollars per share)	$ (0.12)	$ (1.07)
Weighted average common shares:
Weighted average common shares used in computing basic loss per common share (in shares)	68,447	59,836
Weighted average common shares used in computing diluted loss per common share (in shares)	68,447	59,836