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
Movement in valuation and qualifying accounts
Balance at Beginning of Year		$ 8,059	$ 7,919	$ 7,197
Additions Charged to Expenses (Income)		(2,203)	6,653	1,401
Charge-Offs		(1,839)	(6,514)	(600)
Other	[1]	22	1	(79)
Balance at End of Year		4,039	8,059	7,919
Valuation allowance for deferred income tax assets
Movement in valuation and qualifying accounts
Balance at Beginning of Year		6,161	6,317	7,901
Additions Charged to Expenses (Income)		(2,578)	451	(841)
Charge-Offs		0	0	0
Other	[1]	1,206	(607)	(743)
Balance at End of Year		$ 4,789	$ 6,161	$ 6,317

[1] Primarily the impact of currency changes