Schedule II - Valuation and Qualifying Accounts (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
SEC Schedule, 12-09, Allowance, Credit Loss [Member]
SEC Schedule, 12-09, Movement in Valuation Allowances and Reserves [Roll Forward]
Beginning balance	$ (4,143)	$ (2,833)	$ (3,388)
Provision for doubtful accounts	3,571	1,713	1,515
Write-off of accounts receivable against allowance/Other	(745)	(403)	(2,070)
Ending balance	(6,969)	(4,143)	(2,833)
SEC Schedule, 12-09, Valuation Allowance, Operating Loss Carryforward [Member]
SEC Schedule, 12-09, Movement in Valuation Allowances and Reserves [Roll Forward]
Beginning balance	(35)	(3,747)	(5,979)
Decrease (increase)	(1,996)	3,712	2,232
Ending balance	$ (2,031)	$ (35)	$ (3,747)