Acquired Intangible Assets, Net (Schedule of Acquired Intangible Assets, Net) (Details) - USD ($) $ in Thousands	6 Months Ended	12 Months Ended
	Jun. 30, 2015	Dec. 31, 2014
Acquired Intangible Assets, Net [Line Items]
Acquired intangible asset, net of accumulated amortization	$ 211,865	$ 204,511
Acquired intangible asset, accumulated amortization	$ 30,865	$ 21,765
Acquired intangible asset, weighted average remaining life	15 years 2 months 12 days	15 years 7 months 6 days
In-place leases [Member]
Acquired Intangible Assets, Net [Line Items]
Acquired intangible asset, net of accumulated amortization	$ 205,649	$ 198,710
Acquired intangible asset, accumulated amortization	$ 29,985	$ 21,105
Acquired intangible asset, weighted average remaining life	14 years 8 months 12 days	15 years 1 month 6 days
Above-market leases [Member]
Acquired Intangible Assets, Net [Line Items]
Acquired intangible asset, net of accumulated amortization	$ 3,559	$ 3,118
Acquired intangible asset, accumulated amortization	$ 723	$ 529
Acquired intangible asset, weighted average remaining life	11 years 4 months 24 days	11 years 4 months 24 days
Ground lease interest [Member]
Acquired Intangible Assets, Net [Line Items]
Acquired intangible asset, net of accumulated amortization	$ 2,657	$ 2,683
Acquired intangible asset, accumulated amortization	$ 157	$ 131
Acquired intangible asset, weighted average remaining life	60 years 9 months 18 days	61 years 2 months 12 days