Plant, Equipment and Timberlands - Summary of Interest Expense Capitalized (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Interest Expense [Abstract]
Interest cost incurred	$ 7,022	$ 10,408	$ 16,005
Interest capitalized			396
Interest expense	$ 7,022	$ 10,408	$ 15,609