Condensed Consolidated Statements of Income - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2023	Jun. 30, 2022
Services revenue	$ 442.2	$ 381.0	$ 867.5	$ 730.8
Cost of services (exclusive of depreciation and amortization)	376.3	322.2	743.3	620.6
General and administrative expenses	31.8	26.7	62.4	51.2
Depreciation and amortization	8.8	6.5	17.2	13.3
Operating income	25.3	25.6	44.6	45.7
Other expense (income)
Interest expense	7.3	3.5	14.1	8.3
Interest income	(0.1)	(0.1)	(0.2)	(0.3)
Total other expenses	7.2	3.4	13.9	8.0
Earnings before income taxes	18.1	22.2	30.7	37.7
Income tax expense	4.8	5.9	8.1	10.1
Net income	13.3	16.3	22.6	27.6
Less: Net income attributable to noncontrolling interests	1.0	0.9	1.9	1.5
Net income attributable to SP Plus Corporation	$ 12.3	$ 15.4	$ 20.7	$ 26.1
Net income per common share
Basic (in dollars per share)	$ 0.63	$ 0.73	$ 1.05	$ 1.23
Diluted (in dollars per share)	$ 0.62	$ 0.72	$ 1.04	$ 1.22
Weighted average shares outstanding
Basic (in shares)	19,631,772	21,195,819	19,666,684	21,211,299
Diluted (in shares)	19,839,953	21,356,464	19,853,900	21,347,442
Lease and Management Type Contracts
Services revenue	$ 221.3	$ 196.5	$ 437.6	$ 380.9
Cost of services (exclusive of depreciation and amortization)	155.4	137.7	313.4	270.7
Lease Type Contracts
Services revenue	76.3	70.6	144.5	133.2
Cost of services (exclusive of depreciation and amortization)	62.3	55.9	117.5	107.9
Management Type Contracts
Services revenue	145.0	125.9	293.1	247.7
Cost of services (exclusive of depreciation and amortization)	93.1	81.8	195.9	162.8
Reimbursed Management Type Contract Revenue
Services revenue	220.9	184.5	429.9	349.9
Cost of services (exclusive of depreciation and amortization)	$ 220.9	$ 184.5	$ 429.9	$ 349.9