Consolidated Statements of Comprehensive (Loss) Income - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Statement Of Income And Comprehensive Income [Abstract]
Net income (loss)	$ 35.3	$ (172.9)	$ 51.7
Reclassification of de-designated interest rate collars	1.7	1.1
Change in fair value of interest rate collars		(2.9)	(0.4)
Foreign currency translation (loss) gain	(0.1)	0.1	0.1
Comprehensive income (loss)	36.9	(174.6)	51.4
Less: Comprehensive income (loss) attributable to noncontrolling interest	3.6	(0.1)	2.9
Comprehensive income (loss) attributable to SP Plus Corporation	$ 33.3	$ (174.5)	$ 48.5