Income Taxes - Additional Information (Details) - USD ($) $ in Millions		3 Months Ended	12 Months Ended
	Dec. 22, 2017	Dec. 31, 2017	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Income Taxes
Reclassification into deferred tax asset, non current		$ 15.9	$ 15.9	$ 17.9
Income tax expense as a result of change in enacted tax rate, amount		0.2	0.9
Provisional income tax benefit	$ (1.6)
Provisional income tax expense	1.2
Transition tax for accumulated foreign earnings	1.8
Transition tax for accumulated foreign earnings current	14.1
Transition tax for accumulated foreign earnings noncurrent	$ 0.6
Valuation allowances attributable to state net operating loss carryforwards and other state deferred tax assets of Central Parking		7.1	7.1	6.6
Change in valuation allowance			0.5	(0.2)	$ (5.5)
Taxes paid for United States federal, state and foreign income taxes			26.5	$ 17.6	18.1
State
Income Taxes
Operating loss carryforwards, amount		20.6	20.6
Canada
Income Taxes
Foreign subsidiary earnings permanently reinvested to satisfy current working capital requirements		2.5	2.5
Tax that may be payable on distribution of foreign subsidiary earnings to the United States		0.1	0.1
Puerto Rico
Income Taxes
Foreign subsidiary earnings permanently reinvested to satisfy current working capital requirements		9.2	9.2
Tax that may be payable on distribution of foreign subsidiary earnings to the United States		$ 0.7	$ 0.7
Accounting Standards Update 2015-07 | New Accounting Pronouncement, Early Adoption, Effect
Income Taxes
Reclassification into deferred tax asset, non current					$ 12.3