Consolidated Statements of Comprehensive Income - USD ($) $ in Millions	12 Months Ended
Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Statement of Comprehensive Income [Abstract]
Net income	$ 44.5	$ 26.0	$ 20.3
Other comprehensive income (loss)	0.2	(0.3)	(0.9)
Comprehensive income	44.7	25.7	19.4
Less: Comprehensive income attributable to noncontrolling interest	3.3	2.9	2.9
Comprehensive income attributable to SP Plus Corporation	$ 41.4	$ 22.8	$ 16.5

Amount after tax of increase (decrease) in equity from transactions and other events and circumstances from net income and other comprehensive income, attributable to parent entity. Excludes changes in equity resulting from investments by owners and distributions to owners.

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Amount after tax of increase (decrease) in equity from transactions and other events and circumstances from net income (loss) and other comprehensive income (loss), attributable to noncontrolling interests. Excludes changes in equity resulting from investments by owners and distributions to owners.

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Amount after tax of other comprehensive income (loss) attributable to parent entity.

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