Stockholders' Equity - Reclassifications from Accumulated Comprehensive Loss (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Other expense, net									$ 2,603	$ 3,056	$ 9,443
Income before income taxes									(59,186)	(121,353)	(88,355)
Provision for (benefit from) income taxes									6,226	28,162	(22,164)
Net income (loss)	$ 1,574	$ (11,588)	$ (23,008)	$ (19,938)	$ (23,347)	$ (24,015)	$ (21,879)	$ (23,950)	(52,960)	(93,191)	(110,519)
Amortization of actuarial loss and net transition obligation | Reclassification out of Accumulated Other Comprehensive Income
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Other expense, net									364	330	397
Amortization of prior service cost | Reclassification out of Accumulated Other Comprehensive Income
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Other expense, net									2	1	2
Settlement loss | Reclassification out of Accumulated Other Comprehensive Income
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Other expense, net									508	479	0
Accumulated Defined Benefit Plans Adjustment Including Portion Attributable to Noncontrolling Interest | Reclassification out of Accumulated Other Comprehensive Income
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Income before income taxes									874	810	399
Provision for (benefit from) income taxes									(230)	(210)	(141)
Net income (loss)									$ 644	$ 600	$ 258