Stockholders' Equity - Reclassifications from accumulated comprehensive loss (Details) - USD ($) $ in Thousands		3 Months Ended																12 Months Ended
		Dec. 31, 2018	[1]	Sep. 30, 2018	[1],[2]	Jun. 30, 2018	[1],[2]	Mar. 31, 2018	[1],[2]	Dec. 31, 2017	[1],[2]	Sep. 30, 2017	[1],[2]	Jun. 30, 2017	[1],[2]	Mar. 31, 2017	[1],[2]	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Other expense, net																		$ 2,943	$ 10,377	$ 9,354
Income (loss) before income taxes																		(123,291)	(90,788)	18,943
Provision for (benefit from) income taxes																		28,796	(21,876)	(8,043)
Net income (loss)		$ (22,732)		$ (25,494)		$ (22,075)		$ (24,194)		$ (61,225)		$ (18,820)		$ (19,033)		$ (13,586)		(94,495)	(112,664)	10,900
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	[3]																	330	397	362
Amortization of prior service cost (1) | Reclassification out of Accumulated Other Comprehensive Income
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Other expense, net	[3]																	1	2	2
Settlement loss | Reclassification out of Accumulated Other Comprehensive Income
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Other expense, net	[3]																	479
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 (loss) before income taxes																		810	399	364
Provision for (benefit from) income taxes																		(210)	(141)	(129)
Net income (loss)																		$ 600	$ 258	$ 235

[1] Includes a net tax benefit related to the Tax Reform Act during the three months ended December 31, 2017. See Note 15—Income Taxes for additional information.

[2] We revised our previously issued financial statements to correct immaterial errors. See Note 1 for additional information.

[3] These accumulated comprehensive loss components are included in the computation of net periodic benefit cost (See Note16—Employee Benefit Plans for additional information).