Income taxes - Deferred Tax Liabilities and Assets (Detail) - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Deferred tax liabilities
Accelerated depreciation	$ 67,697	$ 67,479
Accelerated amortization of deductible intangibles	534,438	536,740
Right-of-use assets for operating leases	21,648	24,220
Other	3,792	3,322
Total deferred tax liabilities	627,575	631,761
Deferred tax assets
Accrued compensation costs	24,147	18,559
Pension and post-retirement medical and life	17,400	25,523
Loss carryforwards	31,841	38,348
Operating lease liabilities	22,582	25,319
Other	25,160	37,239
Total deferred tax assets	121,130	144,988
Deferred tax asset valuation allowance	41,929	43,467	$ 45,661	$ 125,894
Total net deferred tax (liabilities)	$ (548,374)	$ (530,240)