Debt - Schedule of Maturity Amounts Outstanding Under Credit Agreement and Senior Unsecured Notes (Detail) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2023	Dec. 31, 2022
Line of Credit Facility [Line Items]
Borrowings under credit agreement, outstanding amount	$ 75,000	$ 70,000
Borrowings under note purchase and guarantee agreement, outstanding amount	673,343	623,492
Total	750,000	695,000
Unamortized debt issuance costs, net	(3,207)	(3,545)
Total debt, net	$ 746,793	691,455
Revolving Credit Facility [Member]
Line of Credit Facility [Line Items]
Maturity Date	Oct. 27, 2025
Interest Rate	6.70%
Borrowings under credit agreement, outstanding amount	$ 75,000	70,000
Total	$ 75,000
Series B Notes Maturing in June 2023 [Member]
Line of Credit Facility [Line Items]
Maturity Date	Jun. 02, 2023
Interest Rate	5.35%
Borrowings under note purchase and guarantee agreement, outstanding amount		75,000
Series C Notes Maturing in February 2025 [Member]
Line of Credit Facility [Line Items]
Maturity Date	Feb. 25, 2025
Interest Rate	4.75%
Borrowings under note purchase and guarantee agreement, outstanding amount	$ 50,000	50,000
Series D-E Notes Maturing in June 2028 [Member]
Line of Credit Facility [Line Items]
Maturity Date	Jun. 21, 2028
Interest Rate	5.47%
Borrowings under note purchase and guarantee agreement, outstanding amount	$ 100,000	100,000
Series F-H Notes Maturing in September 2029 [Member]
Line of Credit Facility [Line Items]
Maturity Date	Sep. 12, 2029
Interest Rate	3.52%
Borrowings under note purchase and guarantee agreement, outstanding amount	$ 125,000	125,000
Series I-K Notes Maturing in November 2030 [Member]
Line of Credit Facility [Line Items]
Maturity Date	Nov. 25, 2030
Interest Rate	3.43%
Borrowings under note purchase and guarantee agreement, outstanding amount	$ 175,000	175,000
Series L-N Notes Maturing in February 2032 [Member]
Line of Credit Facility [Line Items]
Maturity Date	Feb. 22, 2032
Interest Rate	3.45%
Borrowings under note purchase and guarantee agreement, outstanding amount	$ 100,000	$ 100,000
Series O-Q Notes Maturing in January 2033 [Member]
Line of Credit Facility [Line Items]
Maturity Date	Jan. 20, 2033
Interest Rate	3.65%
Borrowings under note purchase and guarantee agreement, outstanding amount	$ 125,000