Condensed Consolidated Statements of Income - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Services revenue	$ 460.7	$ 404.4	$ 1,328.2	$ 1,135.2
Cost of services (exclusive of depreciation and amortization)	393.1	346.2	1,136.4	966.8
General and administrative expenses	37.6	27.2	100.0	78.4
Depreciation and amortization	9.0	7.2	26.2	20.5
Operating income	21.0	23.8	65.6	69.5
Other expense (income)
Interest expense	7.4	3.9	21.5	12.2
Interest income		(0.1)	(0.2)	(0.4)
Total other expenses	7.4	3.8	21.3	11.8
Earnings before income taxes	13.6	20.0	44.3	57.7
Income tax expense	3.5	4.9	11.6	15.0
Net income	10.1	15.1	32.7	42.7
Less: Net income attributable to noncontrolling interests	0.9	0.8	2.8	2.3
Net income attributable to SP Plus Corporation	$ 9.2	$ 14.3	$ 29.9	$ 40.4
Net income per common share
Basic (in dollars per share)	$ 0.47	$ 0.69	$ 1.52	$ 1.92
Diluted (in dollars per share)	$ 0.46	$ 0.68	$ 1.5	$ 1.90
Weighted average shares outstanding
Basic (in shares)	19,649,611	20,744,813	19,660,930	21,054,095
Diluted (in shares)	19,910,308	20,977,667	19,874,165	21,223,982
Lease and Management Type Contracts
Services revenue	$ 228.4	$ 207.1	$ 666.0	$ 588.0
Cost of services (exclusive of depreciation and amortization)	160.8	148.9	474.2	419.6
Management Type Contracts
Services revenue	153.5	134.9	446.6	382.6
Cost of services (exclusive of depreciation and amortization)	99.9	89.9	295.8	252.7
Lease Type Contracts
Services revenue	74.9	72.2	219.4	205.4
Cost of services (exclusive of depreciation and amortization)	60.9	59.0	178.4	166.9
Reimbursed Management Type Contract Revenue
Services revenue	232.3	197.3	662.2	547.2
Cost of services (exclusive of depreciation and amortization)	$ 232.3	$ 197.3	$ 662.2	$ 547.2