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Commitments and Contingencies (Lease Commitments) (Details) - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Operating and Capital Leased Assets [Line Items] [Line Items]
Expenses under real property, equipment, and sofware leases		$ 56.3	$ 52.8	$ 51.4
Capital Leases, Future Minimum Payments Due, Fiscal Year Maturity [Abstract]
Noncancelable Lease Commitments, Capital, 2018		21.0
Noncancelable Lease Commitments, Capital, 2019		34.4
Noncancelable Lease Commitments, Capital, 2020		9.1
Noncancelable Lease Commitments, Capital, 2021		8.8
Noncancelable Lease Commitments, Capital, 2022		8.9
Noncancelable Lease Commitments, Capital, Thereafter		97.6
Noncancelable Lease Commitments, Capital, Total minimum payments		179.8
Noncancelable Lease Commitments, Capital, Amounts representing interest		(58.0)
Noncancelable Lease Commitments, Capital, Total		121.8
Operating Leases, Future Minimum Payments Due, Fiscal Year Maturity [Abstract]
Noncancelable Lease Commitments, Operating, 2018	[1]	54.3
Noncancelable Lease Commitments, Operating, 2019	[1]	49.9
Noncancelable Lease Commitments, Operating, 2020	[1]	46.1
Noncancelable Lease Commitments, Operating, 2021	[1]	42.3
Noncancelable Lease Commitments, Operating, 2022	[1]	39.2
Noncancelable Lease Commitments, Operating, Thereafter	[1]	301.6
Noncancelable Lease Commitments, Operating, Total minimum payments	[1]	533.4
Minimum sublease income		$ 1.9
Minimum [Member]
Operating and Capital Leased Assets [Line Items] [Line Items]
Operating leases, term of contract		1 year
Maximum [Member]
Operating and Capital Leased Assets [Line Items] [Line Items]
Operating leases, term of contract		25 years
[1] Future minimum operating lease payments do not reflect future minimum sublease income of $1.9 million. Additionally, operating leases that are on a month-to-month basis are not included.

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Operating and Capital Leased Assets [Line Items] [Line Items]

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Amount of minimum lease payments for capital leases.

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Amount of minimum lease payments for capital leases due in the next fiscal year following the latest fiscal year. Excludes interim and annual periods when interim periods are reported on a rolling approach, from latest balance sheet date.

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Amount of minimum lease payments for capital leases due in the fifth fiscal year following the latest fiscal year. Excludes interim and annual periods when interim periods are reported on a rolling approach, from latest balance sheet date.

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Amount of minimum lease payments for capital leases due in the fourth fiscal year following the latest fiscal year. Excludes interim and annual periods when interim periods are reported on a rolling approach, from latest balance sheet date.

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Amount of minimum lease payments for capital leases due in the second fiscal year following the latest fiscal year. Excludes interim and annual periods when interim periods are reported on a rolling approach, from latest balance sheet date.

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Amount of minimum lease payments for capital leases due after the fifth fiscal year following the latest fiscal year. Excludes interim and annual periods when interim periods are reported on a rolling approach, from latest balance sheet date.

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Amount necessary to reduce net minimum lease payments to present value for capital leases.

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Present value of minimum lease payments for capital leases net of executory costs, including amounts paid by the lessee to the lessor for insurance, maintenance and taxes.

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Term of lessee's operating lease, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents reported fact of one year, five months, and thirteen days.

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Contractually required future rental payments receivable on noncancelable subleasing arrangements.

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