Long-Term Debt - Schedule of Long-Term Debt (Detail) - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019
Debt Instrument [Line Items]
Total debt, excluding deferred financing costs	$ 1,796,875	$ 1,735,000
Deferred financing costs, net of accumulated amortization	(25,184)	(29,995)
Total debt	1,771,691	1,705,005
Current portion of long-term debt	17,500	17,500
Long-term debt and borrowings under Variable Funding Notes, net of current portion	1,754,191	1,687,505
2018-1 Class A-2-I notes | Senior fixed-rate term notes
Debt Instrument [Line Items]
Total debt, excluding deferred financing costs	563,500	567,813
2018-1 Class A-2-II notes | Senior fixed-rate term notes
Debt Instrument [Line Items]
Total debt, excluding deferred financing costs	612,500	617,187
2019-1 Class A-2 notes | Senior fixed-rate term notes
Debt Instrument [Line Items]
Total debt, excluding deferred financing costs	545,875	550,000
Revolving Financing Facility | Borrowings under Variable Funding Notes
Debt Instrument [Line Items]
Total debt, excluding deferred financing costs	$ 75,000	$ 0