Summary of Significant Accounting Policies - Revised Consolidated Statements of Comprehensive Income (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Revision of Previously Issued Financial Statements
Net income (loss)	$ (25,837)	$ 2,755	$ 110	$ 573	$ 5,012	$ 478	$ 2,825	$ 2,199	$ (22,399)	$ 10,514	$ 42,151
Other Comprehensive income (loss):
Cumulative translation adjustment, net									4,029	(2,488)	(3,292)
Pension adjustment, net									313	(1,736)	(552)
Comprehensive income (loss)									$ (18,057)	6,290	38,307
As Previously Reported
Revision of Previously Issued Financial Statements
Net income (loss)										10,514	42,151
Other Comprehensive income (loss):
Cumulative translation adjustment, net										(2,488)	(3,292)
Pension adjustment, net										(1,211)
Comprehensive income (loss)										6,815	38,859
Adjustment
Other Comprehensive income (loss):
Pension adjustment, net										(525)	(552)
Comprehensive income (loss)										$ (525)	$ (552)