Subsequent Events (Detail) $ / shares in Units, $ in Thousands			3 Months Ended		12 Months Ended
	May 04, 2020 $ / shares	Sep. 20, 2019	Mar. 31, 2020 USD ($) ft² building $ / shares	Mar. 31, 2019 $ / shares	Dec. 31, 2019	Apr. 03, 2020 USD ($) ft² building	Apr. 01, 2020 USD ($)
Subsequent Event [Line Items]
Acquisition Purchase Price | $			$ 203,155
Number of Buildings | building			25
Rentable Square Feet | ft²			863,484
Dividends declared per common share (in dollars per share)			$ 0.215	$ 0.185
Series A Preferred Stock
Subsequent Event [Line Items]
Dividends per share, declared (in dollars per share)			$ 0.367188	0.367188
Preferred Stock, Dividend Rate, Percentage			5.875%		5.875%
Series B Preferred Stock
Subsequent Event [Line Items]
Dividends per share, declared (in dollars per share)			$ 0.367188	$ 0.367188
Preferred Stock, Dividend Rate, Percentage			5.875%		5.875%
Series C Preferred Stock
Subsequent Event [Line Items]
Dividends per share, declared (in dollars per share)			$ 0.351563
Preferred Stock, Dividend Rate, Percentage		5.625%	5.625%		5.625%
Series 2 CPOP Units [Member]
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	Jun. 30, 2020
Dividends Payable, Date to be Paid	Jul. 15, 2020
Subsequent Event | Operating Partnership Units
Subsequent Event [Line Items]
Distributions declared (in dollars per share)	$ 0.215
Dividends Payable, Date of Record	Jun. 30, 2020
Distribution Made to Limited Partner, Distribution Date	Jul. 15, 2020
Subsequent Event | Series A Preferred Stock
Subsequent Event [Line Items]
Dividends per share, declared (in dollars per share)	$ 0.367188
Dividends Payable, Date of Record	Jun. 15, 2020
Dividends Payable, Date to be Paid	Jun. 30, 2020
Subsequent Event | Series B Preferred Stock
Subsequent Event [Line Items]
Dividends per share, declared (in dollars per share)	$ 0.367188
Dividends Payable, Date of Record	Jun. 15, 2020
Dividends Payable, Date to be Paid	Jun. 30, 2020
Subsequent Event | Series C Preferred Stock
Subsequent Event [Line Items]
Dividends per share, declared (in dollars per share)	$ 0.351563
Dividends Payable, Date of Record	Jun. 15, 2020
Dividends Payable, Date to be Paid	Jun. 30, 2020
Subsequent Event | Series 1 CPOP Units | Series 1 CPOP Units
Subsequent Event [Line Items]
Distributions declared (in dollars per share)	$ 0.505085
Dividends Payable, Date of Record	Jun. 15, 2020
Distribution Made to Limited Partner, Distribution Date	Jun. 30, 2020
Subsequent Event | Series 2 CPOP Units [Member] | Series 2 CPOP Units [Member]
Subsequent Event [Line Items]
Distributions declared (in dollars per share)	$ 0.45
Dividends Payable, Date of Record	Jun. 15, 2020
Distribution Made to Limited Partner, Distribution Date	Jun. 30, 2020
Brady Way | Subsequent Event
Subsequent Event [Line Items]
Acquisition Purchase Price | $							$ 900
North Vernon Avenue | Subsequent Event
Subsequent Event [Line Items]
Acquisition Purchase Price | $						$ 15,500
Number of Buildings | building						1
Rentable Square Feet | ft²						71,692