Stockholders' Equity - Additional Information (Detail) - USD ($)			1 Months Ended		3 Months Ended		9 Months Ended
	Mar. 01, 2022	Mar. 01, 2021	Feb. 28, 2021	Mar. 31, 2018	Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2022	Sep. 30, 2021
Shareholders Equity [Line Items]
Payment of regular quarterly dividend							$ 58,704,000	$ 52,807,000
Regular quarterly dividends paid per share							$ 1.23	$ 1.17
Shares issued pursuant to dividend reinvestment, shares							1,512	1,996
Proceeds from issuance of common stock under the dividend reinvestment plan							$ 44,000	$ 59,000
Stock based compensation expense							$ 3,543,000	$ 2,974,000
Common Stock [Member]
Shareholders Equity [Line Items]
Shares issued pursuant to dividend reinvestment, shares					1,000		2,000	1,000
2018 ATM Program [Member] | Common Stock [Member]
Shareholders Equity [Line Items]
Shares issued pursuant to Offering/Program net, shares					0	636,000	0	1,688,000
Proceeds from issuance of common stock, net						$ 9,430,000		$ 9,008,000
2018 ATM Program [Member] | Maximum [Member]
Shareholders Equity [Line Items]
Aggregate sales price				$ 125,000,000
ATM Program [Member]
Shareholders Equity [Line Items]
Proceeds from issuance of common stock, net							$ (147,000)	$ 49,008,000
Number of shares allowed for sale under forward provisions					714,136	0	714,136	0
Number of shares settled under forward provisions					0		0
ATM Program [Member] | Common Stock [Member]
Shareholders Equity [Line Items]
Shares issued pursuant to Offering/Program net, shares						636,000		1,668,000
Sale of common stock average gross offering price per share					$ 30.22		$ 30.22
ATM Program [Member] | Maximum [Member]
Shareholders Equity [Line Items]
Aggregate sales price			$ 250,000,000
Amended and Restated 2004 Omnibus Incentive Compensation Plan [Member] | Restricted Stock Units [Member]
Shareholders Equity [Line Items]
Restricted stock units, granted	238,850	192,550