Consolidated Statements of Comprehensive Income (Loss) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Consolidated Statements of Comprehensive Income (Loss)
Net income (loss)	$ (407,088)	$ (51,396)	$ (122,027)
Available-for-sale securities:
Change in net unrealized gains or losses	11	(7)	(6)
Reclassification adjustments for net (gains) losses included in net income			18
Unrealized gain (loss) on available-for-sale securities	11	(7)	12
Minimum pension liability:
Reclassification adjustments for net (gains) losses included in net income			866
Net changes related to minimum pension liability			866
Currency translation adjustments:
Change in currency translation adjustments	5	42	(19)
Reclassification adjustments for net (gains) losses included in net income	(8)		(430)
Net changes related to currency translation adjustments	(3)	42	(449)
Total other comprehensive income (loss), net of tax	8	35	429
Total comprehensive income (loss)	$ (407,080)	$ (51,361)	$ (121,598)