Intangible Assets and Liabilities (Narratives) (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013
Acquired Finite-Lived Intangible Assets and Liabilities
Net amortization of intangibles	$ 10.6	$ 0.5
Minimum
Acquired Finite-Lived Intangible Assets and Liabilities
Finite-lived intangible asset, useful life	1 year
Maximum
Acquired Finite-Lived Intangible Assets and Liabilities
Finite-lived intangible asset, useful life	30 years
Below-market ground lease | Maximum
Acquired Finite-Lived Intangible Assets and Liabilities
Finite-lived intangible asset, useful life	99 years