Reclassifications Out of Accumulated Other Comprehensive Loss (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Balance at beginning of period			$ 809,891
Total amount reclassified from accumulated other comprehensive loss, net of tax, into net income	$ 0	$ 0	0	$ 720
Unrealized loss on available-for-sale securities (Note 17)	(11)	(74)	(15)	(12)
Foreign currency translation adjustments	(10,178)	18,504	(7,018)	7,200
Balance at end of period	824,177		824,177
Accumulated defined benefit plans adjustment attributable to parent
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Balance at beginning of period	(108,183)	(118,656)	(115,552)	(124,848)
Tax benefit	(1,095)	(1,111)	(3,318)	(3,257)
Total amount reclassified from accumulated other comprehensive loss, net of tax, into net income	3,701	3,058	11,070	9,250
Balance at end of period	(104,482)	(115,598)	(104,482)	(115,598)
Accumulated defined benefit plans adjustment, net prior service attributable to parent
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Amounts reclassified from Accumulated other comprehensive loss	(24)	(52)	(72)	(156)
Accumulated defined benefit plans adjustment, net gain (loss) attributable to parent
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Amounts reclassified from Accumulated other comprehensive loss	4,820	4,221	14,460	12,663
Accumulated defined benefit plans adjustment attributable to noncontrolling interest
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Balance at beginning of period	0	0	0	0
Tax benefit	0	0	0	0
Total amount reclassified from accumulated other comprehensive loss, net of tax, into net income	0	0	0	0
Balance at end of period	0	0	0	0
Accumulated defined benefit plans adjustment, net prior service attributable to noncontrolling interest
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Amounts reclassified from Accumulated other comprehensive loss	0	0	0	0
Accumulated defined benefit plans adjustment, net gain (loss) attributable to noncontrolling interest
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Amounts reclassified from Accumulated other comprehensive loss	0	0	0	0
Accumulated net investment gain (loss) attributable to parent
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Balance at beginning of period	(5)	68	(1)	6
Unrealized loss on available-for-sale securities (Note 17)	(11)	(74)	(15)	(12)
Balance at end of period	(16)	(6)	(16)	(6)
Accumulated net investment gain (loss) attributable to noncontrolling interest
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Balance at beginning of period	0	0	0	0
Unrealized loss on available-for-sale securities (Note 17)	0	0	0	0
Balance at end of period	0	0	0	0
Accumulated foreign currency adjustment attributable to parent
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Balance at beginning of period	(70,957)	(106,622)	(66,844)	(89,161)
Total amount reclassified from accumulated other comprehensive loss, net of tax, into net income			0	720
Foreign currency translation adjustments	(13,868)	15,226	(17,981)	(2,955)
Acquisition of noncontrolling interest in consolidated subsidiaries (Note 19)	0	0	0	0
Balance at end of period	(84,825)	(91,396)	(84,825)	(91,396)
Accumulated foreign currency adjustment attributable to noncontrolling interest
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Balance at beginning of period	280	326	372	423
Total amount reclassified from accumulated other comprehensive loss, net of tax, into net income			0	0
Foreign currency translation adjustments	0	294	(92)	197
Acquisition of noncontrolling interest in consolidated subsidiaries (Note 19)	(280)	0	(280)	0
Balance at end of period	$ 0	$ 620	$ 0	$ 620