Financial Instruments and Fair Value Measurements - Carrying Value and Estimated Fair Values (Detail) - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019
Carrying Amount
Financial liabilities:
Interest rate swap	$ 27,370	$ 14,452
Carrying Amount | Credit Facility | 2023 Term A Loan
Financial liabilities:
Senior secured term loan	191,424	207,261
Carrying Amount | Credit Facility | 2024 Term B Loan
Financial liabilities:
Senior secured term loan	307,133	317,936
Fair Value
Financial liabilities:
Interest rate swap	27,370	14,452
Fair Value | Credit Facility | 2023 Term A Loan
Financial liabilities:
Senior secured term loan	189,380	206,388
Fair Value | Credit Facility | 2024 Term B Loan
Financial liabilities:
Senior secured term loan	$ 308,760	$ 324,163