Subsequent Events (Detail) $ / shares in Units, $ in Thousands		3 Months Ended		6 Months Ended		12 Months Ended
	Jul. 20, 2020 $ / shares	Jun. 30, 2020 USD ($) ft² building $ / shares	Jun. 30, 2019 $ / shares	Jun. 30, 2020 USD ($) ft² building $ / shares	Jun. 30, 2019 $ / shares	Dec. 31, 2019	Jul. 17, 2020 USD ($) ft² building	Jul. 01, 2020 USD ($) ft² building
Subsequent Event [Line Items]
Acquisition Purchase Price | $		$ 283,853		$ 283,853
Number of Buildings | building		33		33
Rentable Square Feet | ft²		1,197,073		1,197,073
Dividends declared per common share (in dollars per share)		$ 0.215	$ 0.185	$ 0.430	$ 0.370
5.875% Series A Cumulative Redeemable Preferred Stock
Subsequent Event [Line Items]
Dividends per share, declared (in dollars per share)		0.367188	0.367188	$ 0.734376	0.734376
Preferred Stock, Dividend Rate, Percentage				5.875%		5.875%
5.875% Series B Cumulative Redeemable Preferred Stock
Subsequent Event [Line Items]
Dividends per share, declared (in dollars per share)		0.367188	$ 0.367188	$ 0.734376	$ 0.734376
Preferred Stock, Dividend Rate, Percentage				5.875%		5.875%
5.625% Series C Cumulative Redeemable Preferred Stock
Subsequent Event [Line Items]
Dividends per share, declared (in dollars per share)		$ 0.351563		$ 0.703126
Preferred Stock, Dividend Rate, Percentage				5.625%		5.625%
4.43937% Cumulative Redeemable Convertible Preferred Units
Subsequent Event [Line Items]
Preferred Stock, Dividend Rate, Percentage			4.43937%		4.43937%
4.00% Cumulative Redeemable Convertible Preferred Units
Subsequent Event [Line Items]
Preferred Stock, Dividend Rate, Percentage				4.00%
Subsequent Event | Common Stock
Subsequent Event [Line Items]
Dividends declared per common share (in dollars per share)	$ 0.215
Dividends Payable, Date of Record	Sep. 30, 2020
Dividends Payable, Date to be Paid	Oct. 15, 2020
Subsequent Event | OP Units
Subsequent Event [Line Items]
Distributions declared (in dollars per share)	$ 0.215
Dividends Payable, Date of Record	Sep. 30, 2020
Distribution Made to Limited Partner, Distribution Date	Oct. 15, 2020
Subsequent Event | 5.875% Series A Cumulative Redeemable Preferred Stock
Subsequent Event [Line Items]
Dividends per share, declared (in dollars per share)	$ 0.367188
Dividends Payable, Date of Record	Sep. 15, 2020
Dividends Payable, Date to be Paid	Sep. 30, 2020
Subsequent Event | 5.875% Series B Cumulative Redeemable Preferred Stock
Subsequent Event [Line Items]
Dividends per share, declared (in dollars per share)	$ 0.367188
Dividends Payable, Date of Record	Sep. 15, 2020
Dividends Payable, Date to be Paid	Sep. 30, 2020
Subsequent Event | 5.625% Series C Cumulative Redeemable Preferred Stock
Subsequent Event [Line Items]
Dividends per share, declared (in dollars per share)	$ 0.351563
Dividends Payable, Date of Record	Sep. 15, 2020
Dividends Payable, Date to be Paid	Sep. 30, 2020
Subsequent Event | 4.43937% Cumulative Redeemable Convertible Preferred Units | 4.43937% Cumulative Redeemable Convertible Preferred Units
Subsequent Event [Line Items]
Distributions declared (in dollars per share)	$ 0.505085
Dividends Payable, Date of Record	Sep. 15, 2020
Distribution Made to Limited Partner, Distribution Date	Sep. 30, 2020
Subsequent Event | 4.00% Cumulative Redeemable Convertible Preferred Units | 4.00% Cumulative Redeemable Convertible Preferred Units
Subsequent Event [Line Items]
Distributions declared (in dollars per share)	$ 0.45
Dividends Payable, Date of Record	Sep. 15, 2020
Distribution Made to Limited Partner, Distribution Date	Sep. 30, 2020
Sun Valley | Subsequent Event
Subsequent Event [Line Items]
Acquisition Purchase Price | $								$ 35,100
Number of Buildings | building								4
Rentable Square Feet | ft²								207,374
15650-15700 S. Avalon Blvd | Subsequent Event
Subsequent Event [Line Items]
Acquisition Purchase Price | $								$ 28,100
Number of Buildings | building								2
Rentable Square Feet | ft²								166,088
12133 Greenstone Avenue | Subsequent Event
Subsequent Event [Line Items]
Acquisition Purchase Price | $							$ 5,500
Number of Buildings | building							1
Rentable Square Feet | ft²							12,586