Acquired Intangible Assets and Liabilities (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Acquired Intangible Assets and Liabilities
New intangible assets added	$ 7,500
New intangible liabilities added	$ 400
Weighted average life of intangible assets	4 years 3 months 18 days
Weighted average life of intangible liabilities	5 years 8 months 12 days
Lease contracts above-market value	$ 2,080	$ 2,191
Accumulated amortization	(1,698)	(1,756)
Lease contracts above-market value, net	382	435
Lease contracts below-market value	9,731	9,972
Accumulated amortization	(5,439)	(5,279)
Lease contracts below-market value, net	4,292	4,693
Other identified intangible assets	20,218	13,960
Accumulated amortization	(10,687)	(9,681)
Other identified intangible assets, net	9,531	4,279
Amortization of above and below Market Leases	500	500	$ 600
Accumulated amortization of below-market lease	5,439	5,279
Estimated amortization of acquired below-market leases, net of acquired above-market leases
2017	600
2018	603
2019	280
2020	175
2021	168
Thereafter	2,084
Total	3,910
Estimated amortization of all other identified intangible assets
2017	3,410
2018	2,028
2019	1,509
2020	851
2021	807
Thereafter	926
Total	9,531
Other Intangible Assets [Member]
Acquired Intangible Assets and Liabilities
Amortization of intangible assets	$ 2,000	$ 2,000	$ 3,400