Accumulated Other Comprehensive Income (Details) - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
	Mar. 31, 2020	Dec. 31, 2019	Mar. 31, 2019	Dec. 31, 2018
Accumulated Other Comprehensive Income (Loss), Net of Tax	$ (347,701)	$ (323,673)	$ (289,754)	$ (302,414)
Other Comprehensive Income (Loss), before Reclassifications, Net of Tax	(1,704)	(308)
Other Comprehensive Income (Loss), Foreign Currency Transaction and Translation Adjustment, Net of Tax	(27,475)	10,400
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax	5,151	2,568
Other Comprehensive Income (Loss), Net of Tax	(24,028)	12,660
Accumulated Translation Adjustment [Member]
Accumulated Other Comprehensive Income (Loss), Net of Tax	(83,465)	(61,015)	(55,249)	(63,913)
Other Comprehensive Income (Loss), before Reclassifications, Net of Tax	0	0
Other Comprehensive Income (Loss), Foreign Currency Transaction and Translation Adjustment, Net of Tax	(22,450)	8,664
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax	0	0
Other Comprehensive Income (Loss), Net of Tax	(22,450)	8,664
Accumulated Net Gain (Loss) from Designated or Qualifying Cash Flow Hedges [Member]
Accumulated Other Comprehensive Income (Loss), Net of Tax	(1,278)	(1,222)	(52)	702
Other Comprehensive Income (Loss), before Reclassifications, Net of Tax	(1,704)	(308)
Other Comprehensive Income (Loss), Foreign Currency Transaction and Translation Adjustment, Net of Tax	0	0
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax	1,648	(446)
Other Comprehensive Income (Loss), Net of Tax	(56)	(754)
Accumulated Defined Benefit Plans Adjustment [Member]
Accumulated Other Comprehensive Income (Loss), Net of Tax	(262,958)	(261,436)	$ (234,453)	$ (239,203)
Other Comprehensive Income (Loss), before Reclassifications, Net of Tax	0	0
Other Comprehensive Income (Loss), Foreign Currency Transaction and Translation Adjustment, Net of Tax	(5,025)	1,736
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax	3,503	3,014
Other Comprehensive Income (Loss), Net of Tax	$ (1,522)	$ 4,750