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Percentage of voting interest owned by (or beneficial interest in) the reporting entity (directly or indirectly).

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Amount before tax of gain (loss) not previously recognized resulting from the disposal of a discontinued operation.

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Amount of consideration received or receivable for the disposal of assets and liabilities, including discontinued operation.

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Amount of gain (loss) on sale or disposal of an equity method investment.

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Repayment received or receivable for expenses incurred on behalf of a client or customer, other than those reimbursements received by landlords from tenants.

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Amount of cash and cash equivalents restricted as to withdrawal or usage. Cash includes, but is not limited to, currency on hand, demand deposits with banks or financial institutions, and other accounts with general characteristics of demand deposits. Cash equivalents include, but are not limited to, short-term, highly liquid investments that are both readily convertible to known amounts of cash and so near their maturity that they present insignificant risk of changes in value because of changes in interest rates.

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Percentage of the Variable Interest Entity's (VIE) voting interest owned by (or beneficial interest in) the reporting entity (directly or indirectly).

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Significant Accounting Policies and Practices - Narrative (Details) $ in Millions	1 Months Ended	3 Months Ended
	Oct. 31, 2014	Mar. 31, 2018 USD ($) voting_interest_model_entity variable_interest_entity partnership	Mar. 31, 2017 USD ($)	Jan. 03, 2018	Dec. 31, 2017 USD ($)
Restricted Cash and Investments [Abstract]
Restricted cash and cash equivalents		$ 0.3			$ 0.3
Financial Instruments
Book overdrafts		24.4			$ 29.0
Equity Investments in Unconsolidated Entities
Reimbursed management type contract revenue		172.9	$ 179.0
Reimbursed management type contract expense		$ 172.9	179.0
Number of ownership interest entities \| partnership		29
Voting interest ownership percentage				30.00%
Equity earnings in related investments		$ 0.6	0.7
Pre-tax gain as a result of deconsolidation		$ 10.1	0.0
Ownership percentage	30.00%
Minimum
Equity Investments in Unconsolidated Entities
Voting interest ownership percentage		30.00%
Maximum
Equity Investments in Unconsolidated Entities
Voting interest ownership percentage		50.00%
Primary Beneficiary
Equity Investments in Unconsolidated Entities
Number of ownership interest entities \| variable_interest_entity		24
Not Primary Beneficiary
Equity Investments in Unconsolidated Entities
Number of ownership interest entities \| voting_interest_model_entity		5
Disposed of by sale \| Parkmobile
Equity Investments in Unconsolidated Entities
Gross sale price		$ 19.0
Net gain on sale of business		$ 10.1
Reimbursed Management Contract Revenue and Expense
Equity Investments in Unconsolidated Entities
Reimbursed management type contract revenue			12.6
Reimbursed management type contract expense			$ 12.6