Real Estate Investments - Additional Information (Detail) $ in Thousands							3 Months Ended		6 Months Ended
	Jul. 10, 2015 USD ($) ft² shares	Jul. 01, 2015 USD ($) ft²	May. 20, 2015 USD ($)	Apr. 08, 2015 USD ($) shares	Feb. 13, 2015 USD ($)	Jan. 05, 2015 USD ($)	Jun. 30, 2015 USD ($)	Jun. 30, 2014 USD ($)	Jun. 30, 2015 USD ($)	Jun. 30, 2014 USD ($)	Mar. 31, 2015 USD ($)
Real Estate Properties [Line Items]
Land held for development purchased							$ 1,180		$ 1,180
Rental revenues							19,908	$ 15,319	38,098	$ 30,512
Net income (loss)							6,521	$ 1,325	11,626	$ 2,790
Sale of office property									$ 50,613
Sentara Williamsburg [Member]
Real Estate Properties [Line Items]
Sale of office property						$ 15,400
Net proceeds after transaction costs						15,200
Gain (Loss) on disposition of real estate						$ 6,200
Whetstone Apartments [Member]
Real Estate Properties [Line Items]
Acquisition date									May 20, 2015
Net proceeds after transaction costs			$ 35,500
Proceeds from sale of Whetstone Apartments			35,600
Gain on disposition of Apartments			$ 7,200
Subsequent Event [Member] | Common Class B [Member]
Real Estate Properties [Line Items]
Acquisition, common units issued | shares	1,000,000
Oyster Point [Member]
Real Estate Properties [Line Items]
Sale of office property					$ 6,500
Virginia Beach, VA [Member]
Real Estate Properties [Line Items]
Land held for development purchased											$ 1,200
Stone House Square And Mary Land And Perry Hall Market Place [Member]
Real Estate Properties [Line Items]
Acquisition, total consideration				$ 39,800
Acquisition, cash consideration				$ 35,400
Acquisition, common units issued | shares				415,500
Acquisition date									Apr. 08, 2015
Rental revenues							800
Net income (loss)							$ 100
Socastee Commons Myrtle Beach [Member]
Real Estate Properties [Line Items]
Acquisition date									Jul. 01, 2015
Socastee Commons Myrtle Beach [Member] | Subsequent Event [Member]
Real Estate Properties [Line Items]
Acquisition, total consideration		$ 8,700
Area of property acquired | ft²		57,000
Acquisition, assumption of debt		$ 5,000
Socastee Commons Myrtle Beach [Member] | Subsequent Event [Member] | Whetstone Apartments [Member]
Real Estate Properties [Line Items]
Net proceeds after transaction costs and tax protection payments		$ 3,700
Columbus Village In Virginia Beach [Member]
Real Estate Properties [Line Items]
Acquisition date									Jul. 10, 2015
Columbus Village In Virginia Beach [Member] | Subsequent Event [Member]
Real Estate Properties [Line Items]
Area of property acquired | ft²	65,000
Acquisition, assumption of debt	$ 8,800
Columbus Village In Virginia Beach [Member] | Subsequent Event [Member] | Common Class B [Member]
Real Estate Properties [Line Items]
Acquisition, common units issued | shares	1,000,000
Columbus Village In Virginia Beach [Member] | Subsequent Event [Member] | Common Class C [Member]
Real Estate Properties [Line Items]
Acquisition, common units issued | shares	275,000