Acquisitions and Developments in Progress - Acquisition Date Fair Values (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
2020 acquisitions
Acquisition Date Fair Values
Land	$ 57,137		$ 57,137
Building and other improvements, net	1,623		1,623
Acquired lease intangible assets	2,014		2,014
Acquired lease intangible liabilities	(5,534)		(5,534)
Net assets acquired	55,240		$ 55,240
Weighted average amortization period, acquired lease intangible assets			17 years
Weighted average amortization period, acquired lease intangible liabilities			17 years
2019 acquisitions
Acquisition Date Fair Values
Land		$ 14,819		$ 14,819
Building and other improvements, net		13,667		13,667
Acquired lease intangible assets		2,040		2,040
Acquired lease intangible liabilities		(234)		(234)
Net assets acquired		30,292		$ 30,292
Weighted average amortization period, acquired lease intangible assets				6 years
Weighted average amortization period, acquired lease intangible liabilities				5 years
Building and associated improvements
Business Acquisition [Line Items]
Capitalized internal salaries and related benefits	633	679	$ 1,900	$ 2,004
Internal leasing incentives
Business Acquisition [Line Items]
Capitalized internal leasing incentives	$ 66	$ 111	$ 168	$ 247