Components of Interest Expense (Detail) - USD ($)	4 Months Ended	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Interest Expense [Abstract]
Interest expense	$ 26,462,000	$ 31,257,000	$ 35,811,000	$ 26,462,000
Amortization of debt issuance costs 2	2,736,000	3,339,000	2,611,000
Amortization of Debt Discount (Premium)	680,000	811,000	743,000
Interest on borrowings and related fees	32,164,000	29,851,000	36,593,000
Interest Paid, Capitalized, Investing Activities	$ 9,118,000	2,744,000	$ 4,136,000
Accelerated Deferred Debt Issuance Cost		$ 900,000