Commitments and Contingencies - Property Tax Matter (Details) - Litigation - CRNF - USD ($) $ in Millions		12 Months Ended
	Feb. 25, 2013	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009	Dec. 31, 2008	Dec. 31, 2007
Loss Contingencies [Line Items]
Property tax abatement period							10 years
Increase in property tax expenses		$ 11.3	$ 11.4	$ 11.7	$ 10.7	$ 10.7
Decrease in property tax expenses	$ 10.7
Tax exemption period	10 years