Document and Entity Information - shares	9 Months Ended
	Sep. 30, 2019	Oct. 30, 2019
Cover page.
Document Type	10-Q
Amendment Flag	false
Document Quarterly Report	true
Document Period End Date	Sep. 30, 2019
Document Transition Report	false
Entity File Number	000-50796
Entity Registrant Name	SP Plus Corp
Entity Central Index Key	0001059262
Current Fiscal Year End Date	--12-31
Document Fiscal Year Focus	2019
Document Fiscal Period Focus	Q3
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	16-1171179
Entity Address, Address Line One	200 E. Randolph Street, Suite 7700
Entity Address, City or Town	Chicago
Entity Address, State or Province	IL
Entity Address, Postal Zip Code	60601-7702
City Area Code	312
Local Phone Number	274-2000
Title of 12(b) Security	Common Stock, $0.001 par value per share
Trading Symbol	SP
Security Exchange Name	NASDAQ
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Large Accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Shell Company	false
Entity Common Stock, Shares Outstanding		22,948,766