Schedule II - Valuation And Qualifying Accounts (Details) - USD ($) $ in Thousands		12 Months Ended
		Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Allowances for doubtful accounts
Movement in Valuation Allowances and Reserves [Roll Forward]
Balance at beginning of Year		$ 1,342	$ 1,593	$ 1,258
Additions Charged to Expense		2,470	1,355	955
Additions Charged to Other Accounts		49	41	574
Write Offs		(1,529)	(1,602)	(1,162)
Other	[1]	(309)	(45)	(32)
Balance at end of Year		2,023	1,342	1,593
Deferred tax valuation allowance
Movement in Valuation Allowances and Reserves [Roll Forward]
Balance at beginning of Year		3,998	2,837	3,295
Additions Charged to Expense		1,385	1,406
Additions Charged to Other Accounts				402
Write Offs		(1,595)	(176)	(860)
Other	[1]	222	(69)
Balance at end of Year		$ 4,010	$ 3,998	$ 2,837

[1] “Other” primarily includes foreign exchange translation adjustments.