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Income taxes - Schedule of income tax expense (benefit) (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Income Tax Disclosure [Line Items]
Income tax expense	$ 113,681	$ 92,201	$ 94,536
Other comprehensive income:
Unrealized gains (losses) on cash flow hedges	5,265	(3,327)	(4,058)
Retirement benefits	3,859	(894)	(2,720)
Retained earnings:
Deferred tax benefit recognized on adoption of ASU 2016-13	$ (9,263)	(22,587)	$ (16,315)
ASC 326
Retained earnings:
Deferred tax benefit recognized on adoption of ASU 2016-13		$ (935)

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Income Tax Disclosure [Line Items]

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