7. Accumulated Other Comprehensive Income 7. Accumulated Other Comprehensive Income (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance, Accumulated other comprehensive income			$ (46,958)
Total other comprehensive income (loss) net of tax	$ (102,540)	$ (13,589)	(105,155)	$ (91,836)
Ending balance, Accumulated other comprehensive income	(152,113)		(152,113)
Accumulated Translation Adjustment [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance, Accumulated other comprehensive income			(35,500)	77,400
Other Comprehensive Income (Loss), before Reclassifications, before Tax			(109,900)	(91,200)
Reclassification from Accumulated Other Comprehensive Income, Current Period, before Tax			0	0
Other Comprehensive Income (Loss), Tax			0	0
Total other comprehensive income (loss) net of tax			(109,900)	(91,200)
Ending balance, Accumulated other comprehensive income	(145,400)	(13,800)	(145,400)	(13,800)
Accumulated Defined Benefit Plans Adjustment [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance, Accumulated other comprehensive income			(14,800)	(22,300)
Other Comprehensive Income (Loss), before Reclassifications, before Tax			100	500
Reclassification from Accumulated Other Comprehensive Income, Current Period, before Tax			600	1,200
Other Comprehensive Income (Loss), Tax			(200)	(400)
Total other comprehensive income (loss) net of tax			500	1,300
Ending balance, Accumulated other comprehensive income	(14,300)	(21,000)	(14,300)	(21,000)
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	(200)	(400)	(600)	(1,200)
Accumulated Net Unrealized Investment Gain (Loss) [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance, Accumulated other comprehensive income			3,300	4,500
Other Comprehensive Income (Loss), before Reclassifications, before Tax			5,100	(2,300)
Reclassification from Accumulated Other Comprehensive Income, Current Period, before Tax			(300)	300
Other Comprehensive Income (Loss), Tax			(600)	0
Total other comprehensive income (loss) net of tax			4,200	(2,000)
Ending balance, Accumulated other comprehensive income	7,500	2,500	7,500	2,500
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	(300)	300
AOCI Attributable to Parent [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance, Accumulated other comprehensive income			(47,000)	59,600
Other Comprehensive Income (Loss), before Reclassifications, before Tax			(104,700)	(93,000)
Reclassification from Accumulated Other Comprehensive Income, Current Period, before Tax			300	1,500
Other Comprehensive Income (Loss), Tax			(800)	(400)
Total other comprehensive income (loss) net of tax			(105,200)	(91,900)
Ending balance, Accumulated other comprehensive income	$ (152,200)	$ (32,300)	$ (152,200)	$ (32,300)