Acquired In-Place Leases and Above/Below Market Leases Increases (Decreases) in Net Income as Result of Amortization of In-Place Leases Above Market Leases and Below Market Leases (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Acquired Finite-Lived Intangible Assets [Line Items]
Amortization of leases	$ (3,142)	$ (6,732)	$ (10,485)
Amortization of below market leases	5,057	6,440	5,502
In-place leases
Acquired Finite-Lived Intangible Assets [Line Items]
Amortization of leases	(5,903)	(9,120)	(10,248)
Above Market Leases
Acquired Finite-Lived Intangible Assets [Line Items]
Amortization of leases	$ (2,296)	$ (4,052)	$ (5,739)