Fair Value of Financial Instruments - Schedule of Estimated Fair Values and Carrying Values (Parenthetical) (Detail) - Recourse debt [Member] - 5.30% Senior Notes due in 2025 ("2025 Notes") [Member]	9 Months Ended	12 Months Ended
	Sep. 30, 2020	Dec. 31, 2019
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Interest Rate	5.30%	5.30%
Maturity Date	Aug. 31, 2025	Aug. 31, 2025