Acquired In-Place Leases (Details) (USD $)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Acquired Finite-Lived Intangible Assets [Line Items]
Balance of acquired below market leases	$ 109,800,000	$ 111,100,000
Accumulated amortization of below market leases	37,000,000	34,900,000
Amortization from acquired below market lease	5,800,000	5,900,000	4,500,000
Below Market Leases
2015	5,327,000
2016	4,898,000
2017	4,653,000
2018	3,706,000
2019	3,610,000
Thereafter	50,632,000
Total future amortization expense from acquired below market leases	72,826,000
Above Market Leases
Acquired Finite-Lived Intangible Assets [Line Items]
Balance of acquired above market leases	32,700,000	31,100,000
Accumulated amortization of acquired above market leases	19,300,000	16,300,000
Amortization from acquired above market leases	3,400,000	2,800,000	3,400,000
Weighted-average amortization period	5 years 1 month
Above Market Leases
2015	2,892,000
2016	2,476,000
2017	1,784,000
2018	1,275,000
2019	923,000
Thereafter	4,012,000
Total future amortization expense from acquired above market leases	$ 13,362,000
Below Market Lease [Member]
Acquired Finite-Lived Intangible Assets [Line Items]
Weighted-average amortization period	21 years 2 months