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Income taxes - Schedule of income tax expense (benefit) (Detail) - USD ($) $ in Thousands | 12 Months Ended
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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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