Condensed Consolidated Statements of Comprehensive Income - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
Statement of Comprehensive Income [Abstract]
Net income	$ 8.5	$ 9.3
Foreign currency translation (loss) gain	(0.2)	0.2
Comprehensive income	8.3	9.5
Less: Comprehensive income attributable to noncontrolling interests	0.9	0.9
Comprehensive income attributable to SP Plus Corporation	$ 7.4	$ 8.6