Quarterly report pursuant to Section 13 or 15(d)

Stock-based Compensation Plans and Awards - Schedule of assumptions used for determining the per-share fair value (Details)

v2.4.1.9
Stock-based Compensation Plans and Awards - Schedule of assumptions used for determining the per-share fair value (Details) (Employee stock, Black Scholes Options Pricing Model)
3 Months Ended
Mar. 31, 2015
Mar. 31, 2014
Assumptions used to calculate per-share fair value of award    
Expected life 6 months 6 months
Risk-free interest rate (as a percent)   0.08%us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRate
Expected volatility 42.00%us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedVolatilityRate 42.00%us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedVolatilityRate
Expected dividend yield (as a percent) 0.00%us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedDividendRate 0.00%us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedDividendRate
Minimum
   
Assumptions used to calculate per-share fair value of award    
Risk-free interest rate (as a percent) 0.05%us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRate
/ us-gaap_AwardTypeAxis
= us-gaap_EmployeeStockMember
/ us-gaap_RangeAxis
= us-gaap_MinimumMember
/ us-gaap_ValuationTechniqueAxis
= p_BlackScholesOptionsPricingModelMember
 
Maximum
   
Assumptions used to calculate per-share fair value of award    
Risk-free interest rate (as a percent) 0.07%us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRate
/ us-gaap_AwardTypeAxis
= us-gaap_EmployeeStockMember
/ us-gaap_RangeAxis
= us-gaap_MaximumMember
/ us-gaap_ValuationTechniqueAxis
= p_BlackScholesOptionsPricingModelMember