Intangible Assets and Liabilities (Narratives) (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Finite Lived Intangible Assets Liabilities [Line Items]
Net amortization of intangibles	$ 28.0	$ 18.0	$ 4.9
Maximum
Finite Lived Intangible Assets Liabilities [Line Items]
Finite lived intangibles assets useful life	37 years 0 months 0 days
Minimum
Finite Lived Intangible Assets Liabilities [Line Items]
Finite lived intangibles assets useful life	1 year 0 months 0 days