Accumulated Other Comprehensive Income (Details) - USD ($)	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017	Dec. 31, 2017	Dec. 31, 2016
Accumulated Other Comprehensive Income (Loss) [Line Items]
Accumulated Other Comprehensive Income (Loss), Net of Tax	$ 1,832,000	$ 2,818,000	$ 1,832,000	$ 2,818,000	$ 2,070,000	$ 2,414,000
Unrealized Loss on Foreign Currency Derivatives, before Tax			17,000	941,000
Other Comprehensive (Income) Loss, Reclassification Adjustment from AOCI, Pension and Other Postretirement Benefit Plans, Before Tax			(279,000)	(318,000)
Unrealized Foreign Currency Hedge Gain (Loss), Tax	200,000	(46,000)	47,000	(271,000)
Other Comprehensive Income (Loss), Tax			24,000	(219,000)
Accumulated Defined Benefit Plans Adjustment Attributable to Parent [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Accumulated Other Comprehensive Income (Loss), Net of Tax	2,139,000	2,493,000	2,139,000	2,493,000	2,267,000	2,614,000
Unrealized Loss on Foreign Currency Derivatives, before Tax			0	0
Other Comprehensive (Income) Loss, Reclassification Adjustment from AOCI, Pension and Other Postretirement Benefit Plans, Before Tax			(162,000)	(173,000)
Other Comprehensive Income (Loss), Tax			34,000	52,000
Accumulated Foreign Currency Adjustment Attributable to Parent [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Accumulated Other Comprehensive Income (Loss), Net of Tax	$ (307,000)	$ 325,000	(307,000)	325,000	$ (197,000)	$ (200,000)
Unrealized Loss on Foreign Currency Derivatives, before Tax			17,000	941,000
Derivative Instruments, Gain (Loss) Reclassified from Accumulated OCI into Income, Effective Portion, Net			(117,000)	(145,000)
Unrealized Foreign Currency Hedge Gain (Loss), Tax			$ (10,000)
Other Comprehensive Income (Loss), Tax				$ (271,000)