Net Income Per Common Share (Details) (USD $) In Thousands, except Share data, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Net Income Per Common Share
Net income attributable to SP Plus Corporation	$ 5,161	$ 3,744	$ 3,444	$ (260)	$ (6,656)	$ 2,194	$ 4,072	$ 1,730	$ 12,089	$ 1,340	$ 17,098
Basic weighted average common shares outstanding	21,938,377	21,911,574	21,889,777	21,870,771	21,836,583	15,668,129	15,665,263	15,563,914	21,902,870	17,179,606	15,703,595
Dilutive impact of share-based awards									346,714	310,598	344,284
Diluted weighted average common shares outstanding	22,319,723	22,285,723	22,221,102	21,870,771	21,836,583	15,928,685	15,900,659	15,820,118	22,249,584	17,490,204	16,047,879
Net income per common share:
Basic (in dollars per share)	$ 0.24	$ 0.17	$ 0.16	$ (0.01)	$ (0.30)	$ 0.14	$ 0.26	$ 0.11	$ 0.55	$ 0.08	$ 1.09
Diluted (in dollars per share)	$ 0.23	$ 0.17	$ 0.15	$ (0.01)	$ (0.30)	$ 0.14	$ 0.26	$ 0.11	$ 0.54	$ 0.08	$ 1.07
Potential shares of common stock attributable to stock options excluded from net income per common share calculation									0	0	0