Notes Payable - Components of Notes Payable (Detail) - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020
Debt Instrument [Line Items]
Notes payable	$ 426,500	$ 222,771
Unamortized debt issuance cost	(49)	(17)
Notes payable, net	426,451	222,754
Unsecured Revolving Lines of Credit [Member]
Debt Instrument [Line Items]
Notes payable	266,500	122,771
Series B senior notes [Member] | 3.68% Series B senior notes due in 2021 [Member]
Debt Instrument [Line Items]
Notes payable		40,000
Series C senior notes [Member] | 3.84% Series C senior notes due in 2022 [Member]
Debt Instrument [Line Items]
Notes payable	60,000	$ 60,000
Series E senior notes [Member] | 2.35% Series E senior notes due in 2026 [Member]
Debt Instrument [Line Items]
Notes payable	60,000
Series D senior notes [Member] | 2.57% Series D senior notes due in 2028 [Member]
Debt Instrument [Line Items]
Notes payable	$ 40,000