SCHEDULE II - VALUATION AND QUALIFYING ACCOUNTS (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Allowance for doubtful accounts
VALUATION AND QUALIFYING ACCOUNTS
Balance at the Beginning of the Period	$ 3,161	$ 2,989	$ 2,710
Charged to Costs and Expenses	923	235	561
Deductions from Reserve	(543)	(63)	(282)
Balance at the End of the Period	3,541	3,161	2,989
Deferred tax valuation allowance
VALUATION AND QUALIFYING ACCOUNTS
Balance at the Beginning of the Period	5,414	4,070	6,125
Charged to Costs and Expenses	4,230	3,640	535
Charged to Other Accounts	2,604
Deductions from Reserve	(1,059)	(2,296)	(2,590)
Balance at the End of the Period	$ 11,189	$ 5,414	$ 4,070