Accumulated Other Comprehensive (Loss) Income (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Balance	$ 651,983	$ 731,774	$ 920,091
Other comprehensive income before reclassifications	296	213	1,445
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax		(9,665)
Other comprehensive income (loss)	296	(9,452)	1,445
Balance	24,914	651,983	731,774
Total [Member]
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Balance	(5,479)	3,973	2,528
Balance	(5,183)	(5,479)	3,973
Foreign currency translation adjustment [Member]
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Balance	(5,479)	3,924	2,479
Other comprehensive income before reclassifications	296	213	1,445
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax		(9,616)
Other comprehensive income (loss)	296	(9,403)	1,445
Balance	(5,183)	(5,479)	3,924
Unrealized (gain) loss on available for sale securities [Member]
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Balance	0	49	49
Other comprehensive income before reclassifications		0	0
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax		(49)
Other comprehensive income (loss)	0	(49)	0
Balance	$ 0	$ 0	$ 49