Real Estate Investments - Additional Information (Detail) (USD $)	0 Months Ended	3 Months Ended								12 Months Ended			0 Months Ended					4 Months Ended	8 Months Ended	0 Months Ended
	Nov. 20, 2014	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012	Jan. 05, 2015	Feb. 26, 2015	Jan. 17, 2014	Aug. 15, 2014	May 13, 2013	May 12, 2013	Dec. 31, 2013	Feb. 13, 2015	Jan. 09, 2015	Sep. 29, 2014	Apr. 16, 2014	May 01, 2014
Real Estate Properties [Line Items]
Rental revenues		$ 17,521,000	$ 16,713,000	$ 15,319,000	$ 15,193,000	$ 14,992,000	$ 14,899,000	$ 14,231,000	$ 13,398,000	$ 64,746,000	$ 57,520,000	$ 54,436,000
Net income (loss)		5,226,000	2,754,000	2,273,000	2,506,000	2,866,000	1,252,000	8,404,000	1,931,000	7,691,000	7,336,000
Acquisition, development and other pursuit costs										229,000
Identified intangible assets assigned to in-place leases		5,247,000				4,369,000				5,247,000	4,369,000								4,369,000
Land purchased		56,158,000				41,313,000				56,158,000	41,313,000								41,313,000
Sale of Virginia Natural Gas office property	8,900,000
Net proceeds after transaction costs and tax protection payments	7,400,000
Gain (Loss) on disposition of Virginia Natural Gas office property	2,200,000
Sale of office property										7,387,000
Subsequent Event [Member]
Real Estate Properties [Line Items]
Number of grocery stores													2
Combined purchase price													39,100,000
Subsequent Event [Member] | Sentara Williamsburg [Member]
Real Estate Properties [Line Items]
Net proceeds after transaction costs and tax protection payments													15,200,000
Gain (Loss) on disposition of Virginia Natural Gas office property													6,200,000
Sale of office property													15,400,000
Subsequent Event [Member] | Whetstone Apartments [Member]
Real Estate Properties [Line Items]
Proceeds from sale of Whetstone Apartments														35,600,000
Liberty Apartments [Member]
Real Estate Properties [Line Items]
Acquisition, total consideration															26,700,000
Acquisition, common units issued															695,652
Acquisition, assumption of debt															17,000,000
Acquisition, cash consideration															3,000,000
Fair value adjustment to the assumed debt															1,500,000
Outstanding principal balance of the assumed debt															18,500,000
Acquisition date										Jan. 17, 2014
Rental revenues										1,000,000
Net income (loss)										(2,100,000)
Fair value adjustment to the assumed debt															(1,500,000)
Dimmock Square [Member]
Real Estate Properties [Line Items]
Acquisition, total consideration																19,700,000
Acquisition, common units issued																990,952
Acquisition date										Aug. 15, 2014
Rental revenues										800,000
Net income (loss)										(100,000)
Area of property acquired																106,166
Acquisition, cash immediately defeased																10,100,000
Bermuda Crossroads [Member]
Real Estate Properties [Line Items]
Acquisition, total consideration																	3,200,000	3,200,000
Net income (loss)																			3,800,000
Interests in equity method investments of the Predecessor																	50.00%
Total consideration in the form of cash and common units paid																		50.00%
Bermuda Crossroads [Member] | Secured Debt [Member]
Real Estate Properties [Line Items]
Fair value adjustment to the assumed debt																	200,000
Smith's Landing [Member]
Real Estate Properties [Line Items]
Acquisition, total consideration																	7,500,000	5,000,000
Net income (loss)																			200,000
Interests in equity method investments of the Predecessor																	60.00%
Total consideration in the form of cash and common units paid																		40.00%
Identified intangible assets assigned to a below-market ground lease																	1,900,000
Identified intangible assets assigned to in-place leases																	500,000
Virginia Beach, VA [Member]
Real Estate Properties [Line Items]
Land purchased																						200,000
Oyster Point [Member] | Subsequent Event [Member]
Real Estate Properties [Line Items]
Sale of office property																				6,500,000
Bermuda Crossroads and Smith's Landing [Member]
Real Estate Properties [Line Items]
Interests in equity method investments of the Predecessor																	100.00%
Gain on remeasurement of prior equity interests																		9,500,000
Myrtle Beach [Member] | Subsequent Event [Member]
Real Estate Properties [Line Items]
Acquisition, assumption of debt																					5,100,000
Acquisition, cash consideration																					8,700,000
Area of property acquired																					57,000
Williamsburg VA [Member]
Real Estate Properties [Line Items]
Land purchased																							7,600,000
Chesapeake [Member]
Real Estate Properties [Line Items]
Land purchased																								$ 300,000