Retirement plans - Reconciliation of Benefit Obligations, Plan Assets and Funded Status of Company-Sponsored Retirement Plans (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Change in benefit obligations
Benefit obligations as of end of year	$ 605,834
Change in plan assets
Fair value of plan assets as of end of year	541,758
Funded status as of end of year	(64,076)
Amounts recognized in Consolidated Balance Sheets
Pension liabilities—non-current	(58,063)	$ (85,908)
Retirement Plans
Change in benefit obligations
Benefit obligations as of beginning of year	646,662	613,695
Service cost	2	7	$ 8
Interest cost	15,887	19,487	23,066
Actuarial (gain)/loss	(18,246)	48,491
Benefits paid	(35,874)	(35,018)
Settlements	(2,597)	0
Benefit obligations as of end of year	605,834	646,662	613,695
Change in plan assets
Fair value of plan assets as of beginning of year	552,996	479,735
Actual gains return on plan assets	20,896	103,146
Employer contributions	6,337	5,133
Benefits paid	(35,874)	(35,018)
Settlements	(2,597)	0
Fair value of plan assets as of end of year	541,758	552,996	$ 479,735
Funded status as of end of year	(64,076)	(93,666)
Amounts recognized in Consolidated Balance Sheets
Accrued liabilities other—current	(6,013)	(7,758)
Pension liabilities—non-current	$ (58,063)	$ (85,908)