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Amount of ordinary dividend paid during the period for each share of common stock outstanding.

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Cash outflow in the form of ordinary dividends to common shareholders, preferred shareholders and noncontrolling interests, generally out of earnings.

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The cash inflow from the additional capital contribution to the entity.

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Stockholders' Equity - Additional Information (Detail) - USD ($)				1 Months Ended		3 Months Ended
	Mar. 01, 2021	Dec. 14, 2020	Mar. 02, 2020	Feb. 28, 2021	Mar. 31, 2018	Mar. 31, 2021	Mar. 31, 2020
Shareholders Equity [Line Items]
Payment of regular quarterly dividend						$ 17,332,000	$ 15,557,000
Regular quarterly dividends paid per share						$ 0.39	$ 0.37
Shares issued pursuant to dividend reinvestment, shares						649	12,309
Proceeds from issuance of common stock under the dividend reinvestment plan						$ 18,000	$ 394,000
Stock based compensation expense						$ 905,000	$ 732,000
Common Stock [Member]
Shareholders Equity [Line Items]
Shares issued pursuant to dividend reinvestment, shares						1,000	12,000
2018 ATM Program [Member] \| Common Stock [Member]
Shareholders Equity [Line Items]
Shares issued pursuant to Offering/Program net, shares						743,000	0
Proceeds from issuance of shares						$ 20,266,000
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 shares						$ 20,266,000	$ (27,000)
ATM Program [Member] \| Common Stock [Member]
Shareholders Equity [Line Items]
Shares issued pursuant to Offering/Program net, shares						743,000
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	192,550	15,000	176,050