Significant Accounting Policies (Details 3) (USD $) In Thousands, unless otherwise specified	Jun. 30, 2013	Dec. 31, 2012
Intangible assets:
Total intangible assets	$ 13,602	$ 4,386
Intangible liabilities:
Total intangible liabilities	4,020	458
Assets Held-for-sale [Member]
Intangible assets:
Total intangible assets	0	(188)
Leases, Acquired-in-Place [Member]
Intangible assets:
Total intangible assets	12,644	3,639
Leases, Acquired-in-Place, Market Adjustment [Member]
Intangible assets:
Total intangible assets	958	935
Intangible liabilities:
Total intangible liabilities	4,020	2,161
Liabilities Held For Sale [Member]
Intangible liabilities:
Total intangible liabilities	$ 0	$ (1,703)