Condensed Consolidated Statements of Comprehensive Income - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Statement of Comprehensive Income [Abstract]
Net income	$ 7.7	$ 4.5	$ 15.7	$ 16.8
Other comprehensive expense (income)	0.1	(0.5)	(0.2)	(1.1)
Comprehensive income	7.8	4.0	15.5	15.7
Less: Comprehensive income attributable to noncontrolling interest	0.7	0.8	2.2	2.0
Comprehensive income attributable to SP Plus Corporation	$ 7.1	$ 3.2	$ 13.3	$ 13.7