Accumulated Other Comprehensive Income (Loss) (Details) - USD ($)	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Other Comprehensive Income [Line Items]
Accumulated other comprehensive income (loss)	$ (5,034,000)	$ (8,393,000)	$ (12,162,000)	$ (13,394,000)
Unrealized gains (losses)	(2,514,000)	2,195,000	744,000
Amounts reclassified from accumulated other comprehensive income (loss)	6,291,000	4,822,000	2,844,000
Tax effect	(145,000)	(1,962,000)	(1,137,000)
Unrecognized amounts from defined benefit pension plans	(279,000)	(2,169,000)	(2,032,000)
Tax effect	6,000	883,000	813,000
Net of tax amount	3,359,000	3,769,000	1,232,000
Foreign currency translation adjustments [Member]
Other Comprehensive Income [Line Items]
Accumulated other comprehensive income (loss)	(5,819,000)	(3,305,000)	(5,500,000)	(6,244,000)
Unrealized gains (losses)	(2,514,000)	2,195,000	744,000
Amounts reclassified from accumulated other comprehensive income (loss)	0	0	0
Tax effect	0	0	0
Unrecognized amounts from defined benefit pension plans	0	0	0
Tax effect	0	0	0
Net of tax amount	(2,514,000)	2,195,000	744,000
Defined benefit pension plans [Member]
Other Comprehensive Income [Line Items]
Accumulated other comprehensive income (loss)	785,000	(5,088,000)	(6,662,000)	$ (7,150,000)
Unrealized gains (losses)	0	0	0
Amounts reclassified from accumulated other comprehensive income (loss)	6,291,000	4,822,000	2,844,000
Tax effect	(145,000)	(1,962,000)	(1,137,000)
Unrecognized amounts from defined benefit pension plans	(279,000)	(2,169,000)	(2,032,000)
Tax effect	6,000	883,000	813,000
Net of tax amount	$ 5,873,000	$ 1,574,000	$ 488,000