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Significant Accounting Policies and Practices - Narrative (Details) $ in Millions	1 Months Ended	3 Months Ended			9 Months Ended
	Oct. 31, 2014	Sep. 30, 2019 USD ($)	Sep. 30, 2018 USD ($)	Mar. 31, 2018 USD ($)	Sep. 30, 2019 USD ($) voting_interest_model_entity variable_interest_entity partnership	Sep. 30, 2018 USD ($)	Dec. 31, 2018 USD ($)	Jan. 03, 2018 USD ($)
Cash and cash equivalents
Restricted cash and cash equivalents		$ 0.4			$ 0.4		$ 1.7
Financial Instruments
Book overdrafts		26.0			$ 26.0		$ 34.0
Equity Investments in Unconsolidated Entities
Number of ownership interest entities \| partnership					30
Equity earnings in related investments		$ 0.8	$ 0.7		$ 2.4	$ 1.9
Primary Beneficiary
Equity Investments in Unconsolidated Entities
Number of ownership interest entities \| variable_interest_entity					25
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
Parkmobile, LLC
Equity Investments in Unconsolidated Entities
Ownership percentage	30.00%