Consolidated Statements of Income (Loss) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Services revenue	$ 1,553.5	$ 1,177.2	$ 1,086.9
Cost of services (exclusive of depreciation and amortization)	1,331.8	997.4	1,056.5
General and administrative expenses	109.1	88.2	85.4
Depreciation and amortization	29.7	25.1	29.3
Impairment of goodwill and intangible assets	0.0	0.0	135.3
Operating income (loss)	82.9	66.5	(219.6)
Other expense (income)
Interest expense	17.7	21.2	21.5
Interest income	(0.4)	(0.4)	(0.5)
Other income	0.0	(0.1)	(0.2)
Total other expenses	17.3	20.7	20.8
Earnings (loss) before income taxes	65.6	45.8	(240.4)
Income tax expense (benefit)	17.5	10.5	(67.5)
Net income (loss)	48.1	35.3	(172.9)
Less: Net income (loss) attributable to noncontrolling interest	2.9	3.6	(0.1)
Net income (loss) attributable to SP Plus Corporation	$ 45.2	$ 31.7	$ (172.8)
Net income (loss) per common share
Basic (in dollars per share)	$ 2.17	$ 1.50	$ (8.21)
Diluted (in dollars per share)	$ 2.15	$ 1.48	$ (8.21)
Weighted average shares outstanding
Basic (in shares)	20,809,363	21,166,323	21,056,061
Diluted (in shares)	21,007,068	21,379,983	21,056,061
Lease and Management Type Contracts
Services revenue	$ 794.4	$ 601.5	$ 549.0
Cost of services (exclusive of depreciation and amortization)	572.7	421.7	518.6
Lease Type Contracts
Services revenue	275.7	215.6	189.4
Cost of services (exclusive of depreciation and amortization)	225.8	170.6	195.0
Management Type Contracts
Services revenue	518.7	385.9	359.6
Cost of services (exclusive of depreciation and amortization)	343.2	247.5	226.5
Lease Impairment
Cost of services (exclusive of depreciation and amortization)	3.7	3.6	97.1
Reimbursed Management Type Contract Revenue
Services revenue	759.1	575.7	537.9
Cost of services (exclusive of depreciation and amortization)	$ 759.1	$ 575.7	$ 537.9