Comprehensive Income (Loss) - Components of Comprehensive Income (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Comprehensive Income (Loss), Net of Tax, Attributable to Parent [Abstract]
Net income	$ 6.7	$ 0.6
Effective portion of unrealized loss on cash flow hedge	(0.1)	(0.2)
Foreign currency translation	0.0	0.1
Comprehensive income	6.6	0.5
Less: Comprehensive income attributable to noncontrolling interest	0.7	0.6
Comprehensive income (loss) attributable to SP Plus Corporation	$ 5.9	$ (0.1)