Unaudited Condensed Consolidated Statements of Operations - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Income Statement [Abstract]
Revenue	$ 8,880	$ 34,692	$ 28,296	$ 77,949
Costs and expenses:
Operating expenses (excluding depreciation and amortization)	11,632	38,121	34,473	82,089
Corporate general and administrative	5,395	6,054	9,888	13,335
Depreciation and amortization	468	2,119	2,659	4,379
Research and development	1,638	2,076	4,193	4,360
(Gain) loss on disposal of long-lived assets	(22)	(4)	(55)	1,093
Impairment of fixed and long-lived assets	0	0	57,454	0
Total costs and expenses	19,111	48,366	108,612	105,256
Loss from operations	(10,231)	(13,674)	(80,316)	(27,307)
Other (expense) income:
Gain on lease termination	576	0	576	0
Interest expense	(16)	(16)	(20)	(2,013)
Other income, net	78	693	31	800
Total other expense, net	638	677	587	(1,213)
Loss before income taxes	(9,593)	(12,997)	(79,729)	(28,520)
Income tax benefit	32	192	6,201	503
Loss from continuing operations	(9,561)	(12,805)	(73,528)	(28,017)
(Loss) income from discontinued operations, net of tax	0	(1,608)	0	44,466
Net (loss) income	$ (9,561)	$ (14,413)	$ (73,528)	$ 16,449
Basic earnings (loss) per common share:
Continuing operations (in dollars per share)	$ (0.14)	$ (0.22)	$ (1.17)	$ (0.48)
Discontinued operations, net of tax (in dollars per share)	0	(0.03)	0	0.76
Basic earnings (loss) per common share (in dollars per share)	(0.14)	(0.25)	(1.17)	0.28
Diluted earnings (loss) per common share:
Continuing operations (in dollars per share)	(0.14)	(0.22)	(1.17)	(0.48)
Discontinued operations, net of tax (in dollars per share)	0	(0.03)	0	0.76
Diluted earnings (loss) per common share (in dollars per share)	$ (0.14)	$ (0.25)	$ (1.17)	$ 0.28
Weighted average common shares:
Weighted average common shares used in computing basic earnings (loss) per common share (in shares)	66,035	58,608	62,828	58,491
Weighted average common shares used in computing diluted earnings (loss) per common share (in shares)	66,035	58,608	62,828	58,491