Dividends and Equity Issuance Program - Additional Information (Detail) - USD ($)	3 Months Ended		6 Months Ended	9 Months Ended
	Sep. 30, 2022	Sep. 30, 2021	Jun. 30, 2020	Sep. 30, 2022	Sep. 30, 2021
Dividends and Equity Issuance [Line Items]
Dividends declared and paid	$ 9,800,000	$ 9,600,000		$ 29,326,000	$ 28,830,000
Declared and paid dividends, per share	$ 0.71	$ 0.70		$ 2.125	$ 2.095
At-The-Market Equity Issuance Program (ATM)
Dividends and Equity Issuance [Line Items]
Aggregate sales of threshold amount			$ 100,000,000
Share issued			2,704	0
Average sale price per share			$ 101.30
Net cash proceeds from stock issued			$ 270,000
Payment of stock issuance cost			$ 4,000
At-The-Market Equity Issuance Program (ATM) | Other Expenses
Dividends and Equity Issuance [Line Items]
Payments for stock issuance				$ 508,000