Summary of Significant Accounting Policies (Real Estate Assets) (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Finite-Lived Intangible Assets [Line Items]
Net amortization expense of acquired intangibles	$ 19,030	$ 10,558	$ 7,108
Future amortization expense, 2014	13,421
Future amortization expense, 2015	10,475
Future amortization expense, 2016	6,219
Future amortization expense, 2017	4,537
Future amortization expense, 2018	2,079
Interest expense capitalized	4,889	2,671	4,955
Intangible lease assets and other assets [Member] | Intangible Leases, Acquired-in-Place, Market Adjustment [Member]
Finite-Lived Intangible Assets [Line Items]
Intangible lease assets and liabilities, Cost	65,932	69,360
Intangible lease assets and liabilities, Accumulated Amortization	(41,230)	(37,454)
Intangible lease assets and other assets [Member] | Intangible Leases, Acquired-in-Place [Member]
Finite-Lived Intangible Assets [Line Items]
Intangible lease assets and liabilities, Cost	111,769	117,631
Intangible lease assets and liabilities, Accumulated Amortization	(60,243)	(46,767)
Intangible lease assets and other assets [Member] | Intangible Leases, Tenant Relationships [Member]
Finite-Lived Intangible Assets [Line Items]
Intangible lease assets and liabilities, Cost	27,381	27,880
Intangible lease assets and liabilities, Accumulated Amortization	(4,004)	(3,350)
Accounts payable and accrued liabilities [Member] | Intangible Leases, Acquired-in-Place, Market Adjustment [Member]
Finite-Lived Intangible Assets [Line Items]
Intangible lease assets and liabilities, Cost	101,901	104,012
Intangible lease assets and liabilities, Accumulated Amortization	$ (64,046)	$ (57,625)
Buildings [Member]
Finite-Lived Intangible Assets [Line Items]
Estimated useful life	40 years
Certain Improvements [Member]
Finite-Lived Intangible Assets [Line Items]
Estimated useful lives, description	10 to 20
Certain Improvements [Member] | Minimum [Member]
Finite-Lived Intangible Assets [Line Items]
Estimated useful life	10 years
Certain Improvements [Member] | Maximum [Member]
Finite-Lived Intangible Assets [Line Items]
Estimated useful life	20 years
Equipment and Fixtures [Member]
Finite-Lived Intangible Assets [Line Items]
Estimated useful lives, description	7 to 10
Equipment and Fixtures [Member] | Minimum [Member]
Finite-Lived Intangible Assets [Line Items]
Estimated useful life	7 years
Equipment and Fixtures [Member] | Maximum [Member]
Finite-Lived Intangible Assets [Line Items]
Estimated useful life	10 years