Quarterly report pursuant to Section 13 or 15(d)

Funds Held for Clients and Corporate Investments (Details 2)

v2.4.1.9
Funds Held for Clients and Corporate Investments (Details 2) (USD $)
In Millions, unless otherwise specified
 3 Months Ended 6 Months Ended
Nov. 30, 2014
Security
Nov. 30, 2013
Nov. 30, 2014
Security
Nov. 30, 2013
May 31, 2014
Security
Maturity Date:          
Due in one year or less, Amortized cost $ 393.9us-gaap_AvailableForSaleSecuritiesDebtMaturitiesNextRollingTwelveMonthsAmortizedCostBasis   $ 393.9us-gaap_AvailableForSaleSecuritiesDebtMaturitiesNextRollingTwelveMonthsAmortizedCostBasis    
Due in one year or less, Fair value 396.6us-gaap_AvailableForSaleSecuritiesDebtMaturitiesNextRollingTwelveMonthsFairValue   396.6us-gaap_AvailableForSaleSecuritiesDebtMaturitiesNextRollingTwelveMonthsFairValue    
Due after one year through three years, Amortized cost 751.4payx_AvailableForSaleSecuritiesDebtMaturitiesRollingYearOneThroughThreeAmortizedCostBasis   751.4payx_AvailableForSaleSecuritiesDebtMaturitiesRollingYearOneThroughThreeAmortizedCostBasis    
Due after one year through three years, Fair value 764.9payx_AvailableForSaleSecuritiesDebtMaturitiesRollingYearOneThroughThreeFairValue   764.9payx_AvailableForSaleSecuritiesDebtMaturitiesRollingYearOneThroughThreeFairValue    
Due after three years through five years, Amortized cost 776.1payx_AvailableForSaleSecuritiesDebtMaturitiesRollingYearFourThroughFiveAmortizedCostBasis   776.1payx_AvailableForSaleSecuritiesDebtMaturitiesRollingYearFourThroughFiveAmortizedCostBasis    
Due after three years through five years, Fair value 785.8payx_AvailableForSaleSecuritiesDebtMaturitiesRollingYearFourThroughFiveFairValue   785.8payx_AvailableForSaleSecuritiesDebtMaturitiesRollingYearFourThroughFiveFairValue    
Due after five years, Amortized cost 1,325.0payx_AvailableForSaleSecuritiesDebtMaturitiesRollingAfterFiveYearsAmortizedCost   1,325.0payx_AvailableForSaleSecuritiesDebtMaturitiesRollingAfterFiveYearsAmortizedCost    
Due after five years, Fair value 1,335.0payx_AvailableForSaleSecuritiesDebtMaturitiesRollingAfterYearFiveFairValue   1,335.0payx_AvailableForSaleSecuritiesDebtMaturitiesRollingAfterYearFiveFairValue    
Total, Amortized cost 3,246.4us-gaap_AvailableForSaleDebtSecuritiesAmortizedCostBasis   3,246.4us-gaap_AvailableForSaleDebtSecuritiesAmortizedCostBasis    
Fair value 3,282.3us-gaap_AvailableForSaleSecurities   3,282.3us-gaap_AvailableForSaleSecurities   3,391.4us-gaap_AvailableForSaleSecurities
Funds Held for Clients and Corporate Investments (Textual)          
Net unrealized gain on available-for-sale securities 35.9payx_Netunrealizedgainlossonavailableforsalesecurities   35.9payx_Netunrealizedgainlossonavailableforsalesecurities   34.5payx_Netunrealizedgainlossonavailableforsalesecurities
Number of available-for-sale securities in an unrealized loss position 88us-gaap_AvailableforsaleSecuritiesInUnrealizedLossPositionsQualitativeDisclosureNumberOfPositions1   88us-gaap_AvailableforsaleSecuritiesInUnrealizedLossPositionsQualitativeDisclosureNumberOfPositions1   98us-gaap_AvailableforsaleSecuritiesInUnrealizedLossPositionsQualitativeDisclosureNumberOfPositions1
Gross realized gains 0.1us-gaap_AvailableForSaleSecuritiesGrossRealizedGains 0us-gaap_AvailableForSaleSecuritiesGrossRealizedGains 0.2us-gaap_AvailableForSaleSecuritiesGrossRealizedGains 0.2us-gaap_AvailableForSaleSecuritiesGrossRealizedGains  
Gross realized losses $ 0us-gaap_AvailableForSaleSecuritiesGrossRealizedLosses $ 0us-gaap_AvailableForSaleSecuritiesGrossRealizedLosses $ 0us-gaap_AvailableForSaleSecuritiesGrossRealizedLosses $ 0us-gaap_AvailableForSaleSecuritiesGrossRealizedLosses  
Minimum maturity period for VRDNs primarily categorized as due after five years (in years)     20 years    
Maximum maturity period for VRDNs, primarily categorized as due after five years (in years)     30 years