Accumulated Other Comprehensive Income - Reclassifications from Accumulated Other Comprehensive Income and Included in Earnings (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Beginning balance			$ 207,163	$ 427,569
Amount reclassified and recognized in net income or loss, net of tax	$ 0	$ (5,487)	(544)	(5,964)
Net change in other comprehensive income, net of tax	0	(5,300)	(544)	(5,874)
Ending balance	195,974	431,523	195,974	431,523
Accumulated other comprehensive income
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Beginning balance		6,087	544	6,661
Ending balance	0	787	0	787
Unrealized (gain) loss reclassified and recognized in net loss, net of tax
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Beginning balance			544
Amount reclassified and recognized in net income or loss, net of tax		(5,485)	16	(5,966)
Unrealized gain reclassified and recognized in net loss, net of tax		175		67
Unrealized gain reclassified to accumulated deficit, net of tax
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Amount reclassified and recognized in net income or loss, net of tax			560
Foreign currency translation
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Beginning balance			0
Amount reclassified and recognized in net income or loss, net of tax		(2)		2
Unrealized gain reclassified and recognized in net loss, net of tax		$ 12		$ 23