Pension and other postretirement benefits - Amounts recognized in accumulated other comprehensive (income) loss (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Defined Benefit Plan, Chance in Amounts Recognized in Accumulated Other Comprehensive Income [Roll Forward]
Beginning balance, accumulated other comprehensive (income) loss, net of tax	$ 297,298
Impact of currency translation, accumulated other comprehensive (income) loss, net of tax	63,191	$ (59,758)	$ (4,195)
Ending balance, accumulated other comprehensive (income) loss, net of tax	346,959	297,298
Pension
Defined Benefit Plan, Chance in Amounts Recognized in Accumulated Other Comprehensive Income [Roll Forward]
Beginning balance, prior service cost (credit)	205	173
Net amortization and deferral, prior service cost	(5)	(15)
Actuarial changes in benefit obligation, prior service cost	0	0
Defined benefit plan, plan amendments		47
Impact of currency translation, prior service cost (credit)	0	0
Ending balance, prior service cost (credit)	200	205	173
Beginning balance, net (gain) or loss	232,335	213,816
Net amortization and deferral, net (gain) or loss	(8,584)	(7,432)
Actuarial changes in benefit obligation, net gain (loss)	(4,965)	25,100
Defined benefit plan, net (gain) or loss on plan amendments		0
Impact of currency translation, net (gain) or loss	(847)	851
Ending balance, net (gain) or loss	217,939	232,335	213,816
Beginning balance, deferred taxes	(80,657)	(76,270)
Net amortization and deferral, deferred taxes	1,999	1,738
Actuarial changes in benefit obligation, deferred taxes	1,148	(5,875)
Defined benefit plan, plan amendments on deferred taxes		(9)
Impact of currency translation, deferred taxes	237	(241)
Ending balance, deferred taxes	(77,273)	(80,657)	(76,270)
Beginning balance, accumulated other comprehensive (income) loss, net of tax	151,883	137,719
Net amortization and deferral, accumulated other comprehensive (income) loss, net of tax	(6,590)	(5,709)
Actuarial changes in benefit obligation, accumulated other comprehensive income (loss), net of tax	(3,817)	19,225
Plan amendments in benefit obligation, accumulated other comprehensive income loss, net of tax		38
Impact of currency translation, accumulated other comprehensive (income) loss, net of tax	(610)	610
Ending balance, accumulated other comprehensive (income) loss, net of tax	140,866	151,883	137,719
Other Benefits
Defined Benefit Plan, Chance in Amounts Recognized in Accumulated Other Comprehensive Income [Roll Forward]
Beginning balance, prior service cost (credit)	(4,669)	7
Net amortization and deferral, prior service cost	1,017	(18)
Actuarial changes in benefit obligation, prior service cost	0	0
Defined benefit plan, plan amendments		(4,658)
Ending balance, prior service cost (credit)	(3,652)	(4,669)	7
Beginning balance, net (gain) or loss	3,052	1,909
Net amortization and deferral, net (gain) or loss	41	179
Actuarial changes in benefit obligation, net gain (loss)	(2,288)	964
Defined benefit plan, net (gain) or loss on plan amendments		0
Ending balance, net (gain) or loss	805	3,052	1,909
Beginning balance, deferred taxes	(9)	(825)
Net amortization and deferral, deferred taxes	(243)	(37)
Actuarial changes in benefit obligation, deferred taxes	523	(223)
Defined benefit plan, plan amendments on deferred taxes		1,076
Ending balance, deferred taxes	271	(9)	(825)
Beginning balance, accumulated other comprehensive (income) loss, net of tax	(1,626)	1,091
Net amortization and deferral, accumulated other comprehensive (income) loss, net of tax	815	124
Actuarial changes in benefit obligation, accumulated other comprehensive income (loss), net of tax	(1,765)	741
Plan amendments in benefit obligation, accumulated other comprehensive income loss, net of tax		3,582
Ending balance, accumulated other comprehensive (income) loss, net of tax	$ (2,576)	$ (1,626)	$ 1,091