Investments in Real Estate - Narrative (Details) ft² in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2019 USD ($) ft² a property land_parcel	Sep. 30, 2019 USD ($)	Jun. 30, 2019 USD ($)	Mar. 31, 2019 USD ($)	Dec. 31, 2018 USD ($)	Sep. 30, 2018 USD ($)	Jun. 30, 2018 USD ($)	Mar. 31, 2018 USD ($)	Dec. 31, 2019 USD ($) ft² a property land_parcel building	Dec. 31, 2018 USD ($) ft² a land_parcel building	Dec. 31, 2017 USD ($)
Finite-Lived Intangible Assets [Line Items]
Revenues	$ 45,015,000	$ 43,397,000	$ 41,730,000	$ 40,880,000	$ 39,413,000	$ 37,899,000	$ 37,238,000	$ 37,107,000	$ 171,022,000	$ 151,657,000	$ 132,484,000
Net income	$ 14,821,000	$ 14,784,000	$ 10,379,000	$ 15,532,000	$ 22,972,000	$ 10,122,000	$ 20,137,000	$ 10,057,000	$ 55,516,000	63,289,000	53,095,000
Number of properties | property	220								220
Area of real estate property | a	77.6								77.6
Capitalized interest associated with redevelopment activities									$ 3,200,000	2,500,000	$ 0
Miami [Member] | Disposed of by Sale [Member] | Disposed assets [Member]
Finite-Lived Intangible Assets [Line Items]
Proceeds from sale of property									14,000,000.0	28,600,000
Gain on sale of property									$ 1,800,000	$ 13,100,000
Improved land parcels [Member]
Finite-Lived Intangible Assets [Line Items]
Number of properties | land_parcel	19								19
Area of real estate property | ft²	13,300								13,300
Redevelopment property [Member]
Finite-Lived Intangible Assets [Line Items]
Number of properties | property	4								4
Asset acquisition, consideration transferred									$ 120,400,000
Area of real estate property | ft²	500								500
Asset acquisitions, real estate redevelopment costs									$ 52,400,000
Redevelopment property [Member] | 1775 NW 70th Avenue [Member] | Miami [Member]
Finite-Lived Intangible Assets [Line Items]
Asset acquisition, consideration transferred									$ 10,000,000.0
Area of real estate property | ft²	65								65
Asset acquisitions, lease term									5 years
Asset acquisitions 2019 [Member]
Finite-Lived Intangible Assets [Line Items]
Asset acquisitions, assets acquired and liabilities assumed, net									$ 289,600,000
Asset acquisition, intangible assets acquired									11,600,000
Asset acquisition, intangible liabilities									10,000,000.0
Revenues									7,600,000
Net income									$ 3,000,000.0
Asset acquisitions 2019 [Member] | Industrial property [Member]
Finite-Lived Intangible Assets [Line Items]
Number of properties acquired | building									17
Area of real estate property acquired | ft²									700
Asset acquisitions 2019 [Member] | Improved land parcels [Member]
Finite-Lived Intangible Assets [Line Items]
Number of properties acquired | land_parcel									4
Area of real estate property acquired | a									22.6
Asset acquisitions 2019 [Member] | Land [Member]
Finite-Lived Intangible Assets [Line Items]
Asset acquisition, property additions									$ 224,100,000
Asset acquisitions 2019 [Member] | Building [Member]
Finite-Lived Intangible Assets [Line Items]
Asset acquisition, property additions									$ 53,900,000
Asset acquisitions 2018 [Member]
Finite-Lived Intangible Assets [Line Items]
Area of real estate property acquired | ft²										500
Asset acquisitions, assets acquired and liabilities assumed, net										$ 227,100,000
Asset acquisition, intangible assets acquired										8,600,000
Asset acquisition, intangible liabilities										4,700,000
Revenues										4,800,000
Net income										1,700,000
Asset acquisition, consideration transferred										112,900,000
Asset acquisitions, real estate redevelopment costs										$ 36,800,000
Asset acquisitions 2018 [Member] | Industrial property [Member]
Finite-Lived Intangible Assets [Line Items]
Number of properties acquired | building										17
Area of real estate property acquired | ft²										1,000
Asset acquisitions 2018 [Member] | Improved land parcels [Member]
Finite-Lived Intangible Assets [Line Items]
Number of properties acquired | land_parcel										5
Area of real estate property acquired | a										19.9
Asset acquisitions 2018 [Member] | Redevelopment, building [Member]
Finite-Lived Intangible Assets [Line Items]
Number of properties acquired | building										2
Asset acquisitions 2018 [Member] | Redevelopment, land parcel [Member]
Finite-Lived Intangible Assets [Line Items]
Number of properties acquired | land_parcel										1
Asset acquisitions 2018 [Member] | Land [Member]
Finite-Lived Intangible Assets [Line Items]
Asset acquisition, property additions										$ 154,500,000
Asset acquisitions 2018 [Member] | Building [Member]
Finite-Lived Intangible Assets [Line Items]
Asset acquisition, property additions										$ 64,000,000.0