Commitments and Contingencies (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2011 Years	Dec. 31, 2010	Dec. 31, 2009
Commitments and Contingencies [Abstract]
Operating lease expense	$ 20.4	$ 16.2	$ 19.3
Operating Leases, Future Minimum Payments Due [Abstract]
2012	17.4
2013	13.9
2014	10.5
2015	7.0
2016	2.3
Thereafter	1.9
Total	53.0
Operating Leases, Income Statement, Lease Revenue	126.1	83.4	49.4
Operating Leases, Future Minimum Payments Receivable [Abstract]
Contractual minimum revenue, Current	114.0
Contractual minimum revenue, in Two Years	86.1
Contractual minimum revenue, in Three Years	54.1
Contractual minimum revenue, in Four Years	42.4
Contractual minimum revenue, in Five Years	29.7
Asset Retirement Obligation [Abstract]
Balance, Beginning of Period	5.1	5.0
Liabilities Settled	0	(0.2)
Liabilities Incurred	0.2	0
Revision to cashflow estimate	(0.2)	0
Accretion Expense	0.3	0.3
Balance, End of Period	5.4	5.1	5.0
Letters of Credit Outstanding, Amount	23.2
Square Footage of Real Estate Property	700,000
Acres of land committed to purchase	30
Unrecorded Purchase Commitment, Property	23
Long-term Purchase Commitments, Range of Years, Minimum	1
Long-Term Purchase Commitments, Range of Years, Maximum	3
Long-term Purchase Commitment, Amount	66
Maximum payout of contingent compensation plan	$ 49.4