Operations and Significant Accounting Policies (Accumulated Other Comprehensive Loss) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Accumulated other comprehensive income (loss) [Roll Forward]
Accumulated other comprehensive income (loss), beginning of the period	$ (59,277)
Other Comprehensive Income (Loss), Net of Income Tax	(4,404)	$ (3,540)	$ (710)
Accumulated other comprehensive income (loss), end of the period	(63,681)	(59,277)
Accumulated Other Comprehensive Loss [Member]
Accumulated other comprehensive income (loss) [Roll Forward]
Accumulated other comprehensive income (loss), beginning of the period	(59,277)	(55,737)	(49,078)
Other comprehensive income (loss) before reclassifications, net of tax	(5,498)	803	(3,441)
Amounts reclassified from accumulated other comprehensive income (loss) before tax	1,443	(5,726)	3,602
Reclassification from AOCI, Current Period, Tax	(349)	1,383	(871)
Other Comprehensive Income (Loss), Net of Income Tax	(4,404)	(3,540)	(710)
Accumulated other comprehensive income (loss), end of the period	(63,681)	(59,277)	(55,737)
Cash Flow Hedging Gain (Loss) [Member]
Accumulated other comprehensive income (loss) [Roll Forward]
Accumulated other comprehensive income (loss), beginning of the period	493	4,085	(3,530)
Other comprehensive income (loss) before reclassifications, net of tax	(5,393)	2,936	7,639
Amounts reclassified from accumulated other comprehensive income (loss) before tax	(1,378)	(8,607)	913
Reclassification from AOCI, Current Period, Tax	333	2,079	(221)
Other Comprehensive Income (Loss), Net of Income Tax	(6,438)	(3,592)	8,331
Accumulated other comprehensive income (loss), end of the period	(5,945)	493	4,085
Pension Liability [Member]
Accumulated other comprehensive income (loss) [Roll Forward]
Accumulated other comprehensive income (loss), beginning of the period	(31,691)	(31,718)	(25,813)
Other comprehensive income (loss) before reclassifications, net of tax	(7,068)	(2,158)	(2,711)
Amounts reclassified from accumulated other comprehensive income (loss) before tax	2,821	2,881	2,689
Reclassification from AOCI, Current Period, Tax	(682)	(696)	(650)
Other Comprehensive Income (Loss), Net of Income Tax	(4,929)	27	(672)
Accumulated other comprehensive income (loss), end of the period	(36,620)	(31,691)	(31,718)
Cumulative Translation Adjustment [Member]
Accumulated other comprehensive income (loss) [Roll Forward]
Accumulated other comprehensive income (loss), beginning of the period	(28,079)	(28,104)	(19,735)
Other comprehensive income (loss) before reclassifications, net of tax	6,963	25	(8,369)
Amounts reclassified from accumulated other comprehensive income (loss) before tax	0	0	0
Reclassification from AOCI, Current Period, Tax	0	0	0
Other Comprehensive Income (Loss), Net of Income Tax	6,963	25	(8,369)
Accumulated other comprehensive income (loss), end of the period	$ (21,116)	$ (28,079)	(28,104)
Accounting Standards Update 2018-02 [Member] | Accumulated Other Comprehensive Loss [Member] | Cumulative effect of change in accounting principle(b)
Accumulated other comprehensive income (loss) [Roll Forward]
Cumulative effect of change in accounting principle(b)			(5,949)
Accounting Standards Update 2018-02 [Member] | Pension Liability [Member] | Cumulative effect of change in accounting principle(b)
Accumulated other comprehensive income (loss) [Roll Forward]
Cumulative effect of change in accounting principle(b)			(5,233)
Accounting Standards Update 2018-02 [Member] | Accumulated Gain (Loss), Net, Cash Flow Hedge, Parent | Cumulative effect of change in accounting principle(b)
Accumulated other comprehensive income (loss) [Roll Forward]
Cumulative effect of change in accounting principle(b)			$ (716)