7. Accumulated Other Comprehensive Income 7. Accumulated Other Comprehensive Income (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance, Accumulated other comprehensive income	$ (87,348)
Total other comprehensive income (loss) net of tax	(61,607)	$ (34,007)
Ending balance, Accumulated other comprehensive income	(148,955)
Other (income) expense, net	(3,273)	(18,696)
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	(62,900)	(36,400)
Reclassification from Accumulated Other Comprehensive Income, Current Period, before Tax	0	0
Other Comprehensive Income (Loss), Tax	900	0
Total other comprehensive income (loss) net of tax	(62,000)	(36,400)
Ending balance, Accumulated other comprehensive income	(134,400)	(71,900)
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	200	200
Reclassification from Accumulated Other Comprehensive Income, Current Period, before Tax	300	200
Other Comprehensive Income (Loss), Tax	200	0
Total other comprehensive income (loss) net of tax	700	400
Ending balance, Accumulated other comprehensive income	(21,500)	(14,400)
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	(300)	(200)
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	0	2,000
Reclassification from Accumulated Other Comprehensive Income, Current Period, before Tax	(400)	0
Other Comprehensive Income (Loss), Tax	100	0
Total other comprehensive income (loss) net of tax	(300)	2,000
Ending balance, Accumulated other comprehensive income	6,900	5,300
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	(400)	0
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	(62,700)	(34,200)
Reclassification from Accumulated Other Comprehensive Income, Current Period, before Tax	(100)	200
Other Comprehensive Income (Loss), Tax	1,200	0
Total other comprehensive income (loss) net of tax	(61,600)	(34,000)
Ending balance, Accumulated other comprehensive income	$ (149,000)	$ (81,000)