7. Accumulated Other Comprehensive Income 7. Accumulated Other Comprehensive Income (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance, Accumulated other comprehensive income			$ (87,348)
Total other comprehensive income (loss) net of tax	$ 87,813	$ 31,392	26,206	$ (2,615)
Ending balance, Accumulated other comprehensive income	(61,142)		(61,142)
Other (income) expense, net	(17,229)	(3,896)	(20,502)	(22,592)
Accumulated Translation Adjustment [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance, Accumulated other comprehensive income			(72,400)	(35,500)
Other Comprehensive Income (Loss), before Reclassifications, before Tax			22,000	(6,500)
Reclassification from Accumulated Other Comprehensive Income, Current Period, before Tax			0	0
Other Comprehensive Income (Loss), Tax			400	0
Total other comprehensive income (loss) net of tax			22,400	(6,500)
Ending balance, Accumulated other comprehensive income	(50,000)	(42,000)	(50,000)	(42,000)
Accumulated Defined Benefit Plans Adjustment [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance, Accumulated other comprehensive income			(22,200)	(14,800)
Other Comprehensive Income (Loss), before Reclassifications, before Tax			(300)	(300)
Reclassification from Accumulated Other Comprehensive Income, Current Period, before Tax			700	400
Other Comprehensive Income (Loss), Tax			200	0
Total other comprehensive income (loss) net of tax			600	100
Ending balance, Accumulated other comprehensive income	(21,600)	(14,700)	(21,600)	(14,700)
Accumulated Defined Benefit Plans Adjustment [Member] | Reclassification Out Of Accumulated Other Comprehensive Income [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Other (income) expense, net	(400)	(200)	(700)	(400)
Accumulated Net Unrealized Investment Gain (Loss) [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance, Accumulated other comprehensive income			7,200	3,300
Other Comprehensive Income (Loss), before Reclassifications, before Tax			4,700	4,400
Reclassification from Accumulated Other Comprehensive Income, Current Period, before Tax			(600)	(100)
Other Comprehensive Income (Loss), Tax			(900)	(500)
Total other comprehensive income (loss) net of tax			3,200	3,800
Ending balance, Accumulated other comprehensive income	10,400	7,100	10,400	7,100
Accumulated Net Unrealized Investment Gain (Loss) [Member] | Reclassification Out Of Accumulated Other Comprehensive Income [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Other (income) expense, net	(200)	(100)	(600)	(100)
AOCI Attributable to Parent [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance, Accumulated other comprehensive income			(87,400)	(47,000)
Other Comprehensive Income (Loss), before Reclassifications, before Tax			26,400	(2,400)
Reclassification from Accumulated Other Comprehensive Income, Current Period, before Tax			100	300
Other Comprehensive Income (Loss), Tax			(300)	(500)
Total other comprehensive income (loss) net of tax			26,200	(2,600)
Ending balance, Accumulated other comprehensive income	$ (61,200)	$ (49,600)	$ (61,200)	$ (49,600)