Business Unit Segment Information (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended
Mar. 31, 2015 item	Mar. 31, 2014
Business Unit Segment Information
Number of operating segments	6us-gaap_NumberOfOperatingSegments
Revenues:
Lease contracts	$ 135,815us-gaap_ParkingRevenue	$ 116,635us-gaap_ParkingRevenue
Management contracts	94,058us-gaap_ManagementFeesRevenue	89,955us-gaap_ManagementFeesRevenue
Reimbursed management contract revenue	174,281us-gaap_ReimbursementRevenue	169,178us-gaap_ReimbursementRevenue
Total revenue	404,154us-gaap_SalesRevenueNet	375,768us-gaap_SalesRevenueNet
Gross profit
Lease contracts	7,122stan_LeaseContractsGrossProfit	4,551stan_LeaseContractsGrossProfit
Management contracts	34,068stan_ManagementContractsGrossProfit	30,741stan_ManagementContractsGrossProfit
Total gross profit	41,190us-gaap_GrossProfit	35,292us-gaap_GrossProfit
Gross Margin
General and administrative expenses	25,673us-gaap_GeneralAndAdministrativeExpense	26,066us-gaap_GeneralAndAdministrativeExpense
General and administrative expense percentage of gross profit	62.00%	74.00%
Depreciation and amortization	7,934us-gaap_DepreciationAndAmortization	7,163us-gaap_DepreciationAndAmortization
Operating income	7,583us-gaap_OperatingIncomeLoss	2,063us-gaap_OperatingIncomeLoss
Other expenses (income):
Interest expense	4,043us-gaap_InterestExpense	4,809us-gaap_InterestExpense
Interest income	(60)us-gaap_OtherNonoperatingIncome	(98)us-gaap_OtherNonoperatingIncome
Equity in losses from investment in unconsolidated entity	471
Total other expenses (income)	4,454us-gaap_NonoperatingIncomeExpense	4,711us-gaap_NonoperatingIncomeExpense
Income (loss) before income taxes	3,129	(2,648)
Income tax provision (benefit)	1,335us-gaap_IncomeTaxExpenseBenefit	(7,438)us-gaap_IncomeTaxExpenseBenefit
Net income	1,794us-gaap_ProfitLoss	4,790us-gaap_ProfitLoss
Less: Net income attributable to noncontrolling interest	452	487
Net income attributable to SP Plus Corporation	1,342	4,303
Operating segment \| Region One
Revenues:
Lease contracts	47,224	47,332
Management contracts	20,160	21,631
Total parking services revenue	67,384	68,963
Gross profit
Lease contracts	1,542	660
Management contracts	9,409	8,977
Total gross profit	10,951	9,637
Gross Margin
Lease contracts (as a percent)	3.00%	1.00%
Management contracts (as a percent)	47.00%	42.00%
Operating segment \| Region Two
Revenues:
Lease contracts	31,227	28,761
Management contracts	20,443	20,052
Total parking services revenue	51,670	48,813
Gross profit
Lease contracts	4,524	3,917
Management contracts	8,020	8,589
Total gross profit	12,544	12,506
Gross Margin
Lease contracts (as a percent)	14.00%	14.00%
Management contracts (as a percent)	39.00%	43.00%
Operating segment \| Region Three
Revenues:
Lease contracts	26,408	28,014
Management contracts	6,718	6,487
Total parking services revenue	33,126	34,501
Gross profit
Lease contracts	(464)	(295)
Management contracts	3,404	3,683
Total gross profit	2,940	3,388
Gross Margin
Lease contracts (as a percent)	(2.00%)	(1.00%)
Management contracts (as a percent)	51.00%	57.00%
Operating segment \| Region Four
Revenues:
Lease contracts	29,708	11,350
Management contracts	25,471	25,629
Total parking services revenue	55,179	36,979
Gross profit
Lease contracts	863	586
Management contracts	5,513	6,076
Total gross profit	6,376	6,662
Gross Margin
Lease contracts (as a percent)	3.00%	5.00%
Management contracts (as a percent)	22.00%	24.00%
Operating segment \| Region Five
Revenues:
Lease contracts	1,241	712
Management contracts	17,557	12,921
Total parking services revenue	18,798	13,633
Gross profit
Lease contracts	202	70
Management contracts	3,708	3,515
Total gross profit	3,910	3,585
Gross Margin
Lease contracts (as a percent)	16.00%	10.00%
Management contracts (as a percent)	21.00%	27.00%
Operating segment \| Other
Revenues:
Lease contracts	7	466
Management contracts	3,709	3,235
Total parking services revenue	3,716	3,701
Gross profit
Lease contracts	455	(387)
Management contracts	4,014	(99)
Total gross profit	$ 4,469	$ (486)

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