Consolidated Statements of Income - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Services revenue	$ 1,468.4	$ 1,590.5	$ 1,568.4
Cost of services	1,284.4	1,405.2	1,392.0
Gross profit	184.0	185.3	176.4
General and administrative expenses	91.0	82.9	90.0
Depreciation and amortization	17.9	21.0	33.7
Operating income	75.1	81.4	52.7
Other expense (income)
Interest expense	9.6	9.2	10.5
Interest income	(0.4)	(0.6)	(0.5)
Gain on sale of a business	0.0	(0.1)	0.0
Equity in (earnings) losses from investment in unconsolidated entity	(10.1)	0.7	0.9
Total other expenses (income)	(0.9)	9.2	10.9
Earnings before income taxes	76.0	72.2	41.8
Income tax expense	19.6	27.7	15.8
Net income	56.4	44.5	26.0
Less: Net income attributable to noncontrolling interest	3.2	3.3	2.9
Net income attributable to SP Plus Corporation	$ 53.2	$ 41.2	$ 23.1
Net income per common share
Basic (in dollars per share)	$ 2.38	$ 1.86	$ 1.04
Diluted (in dollars per share)	$ 2.35	$ 1.83	$ 1.03
Weighted average shares outstanding
Basic (in shares)	22,394,542	22,195,350	22,238,021
Diluted (in shares)	22,607,223	22,508,288	22,528,122
Lease type contracts
Services revenue	$ 413.9	$ 563.1	$ 545.0
Cost of services	377.6	518.4	505.6
Gross profit	36.3	44.7	39.4
Management type contracts
Services revenue	361.5	348.2	346.8
Cost of services	213.8	207.6	209.8
Gross profit	147.7	140.6	137.0
Lease And Management Type Contracts
Services revenue	775.4	911.3	891.8
Cost of services	591.4	726.0	715.4
Reimbursed management type contract revenue
Services revenue	693.0	679.2	676.6
Cost of services	$ 693.0	$ 679.2	$ 676.6