Accumulated Other Comprehensive Loss (Reclassifications Out of Accumulated Other Comprehensive Income) (Details) - USD ($) $ in Thousands		3 Months Ended		6 Months Ended
		Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019		Jun. 30, 2018
Schedule of Reclassifciations Out of Accumulated Other Comprehensive Income [Line Items]
Income (loss) before income taxes		$ 40,408	$ 29,155	$ 20,818		$ 26,863
Income tax provision (benefit)		(10,997)	(7,742)	(5,555)		(7,432)
Net income (loss)		29,411	21,413	15,263		19,431
Reclassifications Out of Accumulated Other Comprehensive Income (Loss)
Schedule of Reclassifciations Out of Accumulated Other Comprehensive Income [Line Items]
Net income (loss)	[1]	(171)	(168)	11,460		(336)
Reclassifications Out of Accumulated Other Comprehensive Income (Loss) | Defined Benefit Plan Items
Schedule of Reclassifciations Out of Accumulated Other Comprehensive Income [Line Items]
Amortization of prior-service cost	[1],[2]	(228)	(228)	(456)		(456)
Income (loss) before income taxes	[1]	(228)	(228)	(456)		(456)
Income tax provision (benefit)	[1]	57	60	114		120
Net income (loss)	[1]	(171)	$ (168)	(342)		$ (336)
Reclassifications Out of Accumulated Other Comprehensive Income (Loss) | Cash Flow Hedges
Schedule of Reclassifciations Out of Accumulated Other Comprehensive Income [Line Items]
Interest payments		0		182	[1]
Income (loss) before income taxes	[1]	0		182
Income tax provision (benefit)	[1]	0		(46)
Net income (loss)	[1]	0		136
Reclassifications Out of Accumulated Other Comprehensive Income (Loss) | Foreign Currency Translation Adjustment
Schedule of Reclassifciations Out of Accumulated Other Comprehensive Income [Line Items]
Realized loss on pre-existing investment	[1]	0		11,666
Income (loss) before income taxes	[1]	0		11,666
Income tax provision (benefit)	[1]	0		0
Net income (loss)	[1]	$ 0		$ 11,666

[1] Amounts in parentheses indicate credits to profit/loss

[2] This accumulated other comprehensive loss component is included in the computation of net periodic benefit cost (see Note 6).