Debt - Debt (Parenthetical) (Detail) - USD ($)	Sep. 30, 2024	Dec. 31, 2023
Debt Instrument [Line Items]
Unamortized debt issuance cost	$ 527,000	$ 895,000
Senior unsecured 3.95% note [Member]
Debt Instrument [Line Items]
Unamortized debt issuance cost	122,000	191,000
Senior unsecured 3.86% note [Member]
Debt Instrument [Line Items]
Unamortized debt issuance cost	37,000	105,000
Senior unsecured 2.30% note [Member]
Debt Instrument [Line Items]
Unamortized debt issuance cost	94,000	142,000
Senior unsecured 2.37% note [Member]
Debt Instrument [Line Items]
Unamortized debt issuance cost	99,000	148,000
Senior unsecured 2.73% note [Member]
Debt Instrument [Line Items]
Unamortized debt issuance cost	96,000	175,000
Senior unsecured 2.83% note [Member]
Debt Instrument [Line Items]
Unamortized debt issuance cost	$ 79,000	$ 134,000