Summary of Significant Accounting Policies (Narrative) (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Summary Of Significant Accounting Policies [Line Items]
Useful life of property			40 years
Depreciation expense from operation	$ 11.9	$ 9.7	$ 32.8	$ 27.2
Real estate cost capitalized excluding interest cost	2.9	2.4	7.5	6.3
Real estate interest cost capitalized incurred	1.3	0.9	4.7	3.0
In Place Leases [Member]
Summary Of Significant Accounting Policies [Line Items]
Amortization of lease cost	0.5	0.5	1.8	1.5
Tenant Relationship [Member]
Summary Of Significant Accounting Policies [Line Items]
Amortization of lease cost	$ 0.3	$ 0.4	$ 1.0	$ 1.2
Minimum [Member] | Land, Buildings and Improvements [Member]
Summary Of Significant Accounting Policies [Line Items]
Useful life of property			20 years
Maximum [Member] | Land, Buildings and Improvements [Member]
Summary Of Significant Accounting Policies [Line Items]
Useful life of property			40 years
Maximum [Member] | Leasehold Improvements [Member]
Summary Of Significant Accounting Policies [Line Items]
Useful life of property			20 years