Consolidated Statements of (Loss) Income - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Services revenue	$ 1,086.9	$ 1,663.7	$ 1,468.4
Cost of services	1,056.5	1,435.6	1,284.4
Gross profit	30.4	228.1	184.0
General and administrative expenses	85.4	109.0	91.0
Depreciation and amortization	29.3	29.4	17.9
Impairment of goodwill and intangible assets	135.3	0.0	0.0
Operating (loss) income	(219.6)	89.7	75.1
Other expense (income)
Interest expense	21.5	18.9	9.6
Interest income	(0.5)	(0.3)	(0.4)
Other expenses	0.1	0.0	0.0
Gain on sale of other investments	(0.3)	0.0	0.0
Equity in earnings from investment in unconsolidated entity	0.0	0.0	(10.1)
Total other expenses (income)	20.8	18.6	(0.9)
(Loss) earnings before income taxes	(240.4)	71.1	76.0
Income tax (benefit) expense	(67.5)	19.4	19.6
Net (loss) income	(172.9)	51.7	56.4
Less: Net (loss) income attributable to noncontrolling interest	(0.1)	2.9	3.2
Net (loss) income attributable to SP Plus Corporation	$ (172.8)	$ 48.8	$ 53.2
Net (loss) income per common share
Basic (in dollars per share)	$ (8.21)	$ 2.21	$ 2.38
Diluted (in dollars per share)	$ (8.21)	$ 2.20	$ 2.35
Weighted average shares outstanding
Basic (in shares)	21,056,061	22,080,025	22,394,542
Diluted (in shares)	21,056,061	22,208,032	22,607,223
Lease Type Contracts
Services revenue	$ 189.4	$ 408.9	$ 413.9
Cost of services	195.0	366.9	377.6
Gross profit	(5.6)	42.0	36.3
Management Type Contracts
Services revenue	359.6	526.0	361.5
Cost of services	226.5	339.9	213.8
Gross profit	133.1	186.1	147.7
Lease and Management Type Contracts
Services revenue	549.0	934.9	775.4
Cost of services	421.5	706.8	591.4
Reimbursed Management Type Contract Revenue
Services revenue	537.9	728.8	693.0
Cost of services	537.9	728.8	693.0
Lease Impairment
Cost of services	97.1	0.0	0.0
Gross profit	$ 97.1	$ 0.0	$ 0.0