Accumulated Other Comprehensive Loss - Changes in Accumulated Other Comprehensive Loss (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	$ (258,601)	$ (365,282)	$ (395,899)
Other comprehensive income (loss), net of tax	(747)	3,823	256
Ending balance	(183,772)	(258,601)	(365,282)
Loss on Cash Flow Hedge
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	(2,298)	(3,160)
Other comprehensive loss before reclassification	0	0
Amounts reclassified from accumulated other comprehensive income	862	862
Other comprehensive income (loss), net of tax	862	862
Ending balance	(1,436)	(2,298)	(3,160)
Foreign Currency Items
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	(2,401)	(5,362)
Other comprehensive loss before reclassification	(1,609)	2,961
Amounts reclassified from accumulated other comprehensive income	0	0
Other comprehensive income (loss), net of tax	(1,609)	2,961
Ending balance	(4,010)	(2,401)	(5,362)
AOCI Attributable to Parent
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	(4,699)	(8,522)	(8,778)
Other comprehensive loss before reclassification	(1,609)	2,961
Amounts reclassified from accumulated other comprehensive income	862	862
Other comprehensive income (loss), net of tax	(747)	3,823	256
Ending balance	$ (5,446)	$ (4,699)	$ (8,522)