Other Assets - Summary of Deferred Financing Fees, Deferred Leasing Costs and Capitalized Lease Incentives (Details) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013
Deferred Finance Costs [Abstract]
Deferred Finance Costs, Gross	$ 41,339	$ 45,985
Deferred Finance Costs, Gross, Properties Held-for-sale		272
Accumulated Amortization, Deferred Finance Costs	(24,478)	(21,455)
Accumulated Amortization of Deferred Finance Costs, Properties Held-for-sale		(132)
Deferred Finance Costs, Net	16,861	24,530
Deferred Finance Costs, Net, Properties Held-for-sale		140
Deferred Costs, Leasing, Net [Abstract]
Deferred Costs Leasing, Gross, Properties Held and Used in Operations	184,600	146,996
Deferred Costs Leasing, Gross, Properties Held-for-sale		13,769
Deferred Costs Leasing Accumulated Amortization, Properties Held and Used in Operations	(58,348)	(46,228)
Deferred Costs Leasing Accumulated Amortization, Properties Held-for-sale		(987)
Deferred Costs Leasing, Net, Properties Held and Used in Operations	126,252	100,768
Deferred Costs Leasing, Net, Properties Held-for-sale		12,782
Capital Lease Incentives, Net [Abstract]
Capital Lease Incentives, Gross, Properties Held and Used in Operations	22,650	20,651
Capital Lease Incentives, Gross, Properties Held-for-sale		590
Accumulated Amortization of Capital Lease Incentives, Properties Held and Used in Operations	(7,459)	(5,392)
Accumulated Amortization of Capital Lease Incentives, Properties Held-for-sale		(40)
Capital Lease Incentives, Net, Properties Held and Used in Operations	15,191	15,259
Capital Lease Incentives, Net, Properties Held-for-sale		$ 550