Commitments and Contingencies (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2013	Dec. 31, 2012
Loss Contingencies [Line Items]
Letters of Credit Outstanding, Amount	$ 7.2	$ 7.2
Loss Contingency Accrual, at Carrying Value	7.9
Guarantor Obligations, Maximum Exposure, Undiscounted	5.0
Guarantor Obligations, Contract Period	20 years
Guarantor Obligations, Current Carrying Value	0.8	0.8
Joint Ventures [Member]
Loss Contingencies [Line Items]
Equity method investments ownership percentage	50.00%
Shareholder Agreements, Portion of Directors Entitled to Elect	0.5
Partnership Agreements, Voting Managing Interest, Percent	50.00%
Property Lease Guarantee [Member] | Joint Venture One [Member]
Loss Contingencies [Line Items]
Equity method investments ownership percentage	50.00%
Guarantee Obligations, Maximum Exposure, Percent	50.00%
Operating Lease, Initial Term	10 years 7 months
Operating Lease, Number of Options for Lease Extension	2
Operating Lease, Period Available under Options for Lease Extension	5 years
Operating Leases, Rent Expense, Minimum Rentals	4.8
Financial Guarantee [Member] | Joint Venture Two [Member]
Loss Contingencies [Line Items]
Equity method investments ownership percentage	50.00%
Guarantor Obligations, Maximum Exposure, Undiscounted	3.0
Debt Instrument, Face Amount	32.0
Long-term Debt, Gross	28.9	29.1
Guarantor Obligations, Current Carrying Value	1.5	1.5
Pending Litigation [Member]
Loss Contingencies [Line Items]
Loss Contingency, Range of Possible Loss, Maximum	$ 10.0