Net Income per Common Share (Tables)

12 Months Ended

Dec. 31, 2017

Earnings Per Share [Abstract]

Schedule of reconciliation of the weighted average basic common shares outstanding to weighted average diluted common shares outstanding

A reconciliation of the basic weighted average common shares outstanding to diluted weighted average common shares outstanding is as follows:

	Year Ended December 31,
(millions, except share and per share data)	2017		2016		2015
Net income attributable to SP Plus Corporation	$	41.2	$	23.1	$	17.4
Basic weighted average common shares outstanding	22,195,350		22,238,021		22,189,140
Dilutive impact of share-based awards	312,938		290,101		322,619
Diluted weighted average common shares outstanding	22,508,288		22,528,122		22,511,759
Net income per common share
Basic	$	1.86	$	1.04	$	0.78
Diluted	$	1.83	$	1.03	$	0.77