Commitments and Contingencies Future minimum lease payments (Details) (USD $) In Millions, unless otherwise specified	Dec. 31, 2011
Operating Leases, Future Minimum Payments Due [Abstract]
Rent Obligations, due 2012	$ 313.1
Rent Obligations, due 2013	277.1
Rent Obligations, due 2014	224.0
Rent Obligations, due 2015	186.5
Rent Obligations, due 2016	147.1
Rent Obligations, due thereafter	487.9
Total Rent Obligations	1,635.7
Sublease Rental Income, due 2012	(26.9)
Sublease Rental Income, due 2013	(26.0)
Sublease Rental Income, due 2014	(13.9)
Sublease Rental Income, due 2015	(6.1)
Sublease Rental Income, due 2016	(1.4)
Sublease Rental Income, due thereafter	(0.8)
Total Sublease Rental Income	(75.1)
Net Rent, due 2012	286.2
Net Rent, due 2013	251.1
Net Rent, due 2014	210.1
Net Rent, due 2015	180.4
Net Rent, due 2016	145.7
Net Rent, due thereafter	487.1
Total Net Rent	$ 1,560.6

Operating Leases, Future Minimum Payments Due, Future Minimum Sublease Rentals, Current

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The total of future contractually required payments on leases defined as operating.

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For leases having an initial or remaining non-cancelable letter-terms in excess of one year, required rental payments due within one year of the balance sheet date relating to leases defined as operating.

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Contractually required future rental payments receivable on noncancelable subleasing arrangements.

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For leases having an initial or remaining non-cancelable letter-terms in excess of one year, required rental payments due within the fifth year of the balance sheet date relating to leases defined as operating.

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For leases having an initial or remaining non-cancelable letter-terms in excess of one year, required rental payments due within the fourth year of the balance sheet date relating to leases defined as operating.

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For leases having an initial or remaining non-cancelable letter-terms in excess of one year, required rental payments due within the third year of the balance sheet date relating to leases defined as operating.

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For leases having an initial or remaining non-cancelable letter-terms in excess of one year, required rental payments due within the second year of the balance sheet date relating to leases defined as operating.

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