Rental Property - Acquisitions - Allocation of Consideration (Details) (USD $)	3 Months Ended	0 Months Ended
	Mar. 31, 2015	Jan. 22, 2015
2015 Acquisitions
Allocation of the consideration paid for the acquired assets and liabilities
Land	$ 11,692,000
Buildings	58,686,000
Tenant improvements	1,048,000
Building and land Improvements	3,132,000
Total: Aggregate purchase price	97,083,000
Less: Mortgage note payable assumed	(11,765,000)
Net assets acquired	85,318,000
2015 Acquisitions | In-place leases
Allocation of the consideration paid for the acquired assets and liabilities
Amortizable intangible assets	13,540,000
Weighted Average Amortization Period of Lease Intangibles	5 years 7 months 6 days
2015 Acquisitions | Tenant relationships
Allocation of the consideration paid for the acquired assets and liabilities
Amortizable intangible assets	7,595,000
Weighted Average Amortization Period of Lease Intangibles	8 years 1 month 6 days
2015 Acquisitions | Above market leases
Allocation of the consideration paid for the acquired assets and liabilities
Amortizable intangible assets	2,133,000
Weighted Average Amortization Period of Lease Intangibles	8 years 3 months 18 days
2015 Acquisitions | Below market leases
Allocation of the consideration paid for the acquired assets and liabilities
Below market leases	(743,000)
Weighted Average Amortization Period of Lease Intangibles	7 years 8 months 12 days
Burlington, NJ
Consideration transferred
Purchase price, excluding equity issued		13,000,000
Less: Mortgage note payable assumed		(11,800,000)
Purchase price paid in cash		1,200,000
Burlington, NJ | Common Units
Consideration transferred
Redemption of units for cash (in shares)		812,676
Fair value of common units issued		$ 21,900,000
Trailing-average stock price, number of days included		10 days