Schedule II - Valuation and Qualifying Accounts (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Allowance for Doubtful Accounts
Balance at beginning of period	$ 4,217	$ 5,063	$ 3,748
Charge to expenses	7,375	1,752	1,323
Additions/(Deductions)	(139)	(2,598)	(8)
Balance at end of period	11,453	4,217	5,063
Valuation Allowance for Deferred Tax Assets
Balance at beginning of period	393	393	3,788
Charge to expenses	320
Additions/(Deductions)			(3,395)
Balance at end of period	$ 713	$ 393	$ 393