Annual report pursuant to Section 13 and 15(d)

Composition of Certain Financial Statement Captions - Summary of available-for-sale securities' fair value and gross unrealized losses (Details)

v2.4.1.9
Composition of Certain Financial Statement Captions - Summary of available-for-sale securities' fair value and gross unrealized losses (Details) (USD $)
In Thousands, unless otherwise specified
Dec. 31, 2014
Dec. 31, 2013
Schedule of Available-for-sale Securities [Line Items]    
Available-for-sale securities, continuous unrealized loss position, twelve months or less, fair value $ 197,939us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionLessThanTwelveMonthsFairValue $ 136,005us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionLessThanTwelveMonthsFairValue
Available-for-sale securities, continuous unrealized loss position, twelve months or less, gross unrealized loss (431)p_AvailableforsaleSecuritiesContinuousUnrealizedLossPositionLessthan12MonthsAccumulatedLoss (262)p_AvailableforsaleSecuritiesContinuousUnrealizedLossPositionLessthan12MonthsAccumulatedLoss
Available-for-sale securities, continuous unrealized loss position, twelve months or longer, fair value 12,148us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionTwelveMonthsOrLongerFairValue 0us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionTwelveMonthsOrLongerFairValue
Available-for-sale securities, continuous unrealized loss position, twelve months or longer, gross unrealized loss (22)p_AvailableforsaleSecuritiesContinuousUnrealizedLossPosition12MonthsorLongerAccumulatedLoss 0p_AvailableforsaleSecuritiesContinuousUnrealizedLossPosition12MonthsorLongerAccumulatedLoss
Available-for-sale securities, continuous unrealized loss position, fair value 210,087us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionFairValue 136,005us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionFairValue
Available-for-sale securities, continuous unrealized loss position, gross unrealized loss (453)p_AvailableforsaleSecuritiesContinuousUnrealizedLossPositionAccumulatedLoss (262)p_AvailableforsaleSecuritiesContinuousUnrealizedLossPositionAccumulatedLoss
Corporate debt securities    
Schedule of Available-for-sale Securities [Line Items]    
Available-for-sale securities, continuous unrealized loss position, twelve months or less, fair value 192,699us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionLessThanTwelveMonthsFairValue
/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis
= us-gaap_CorporateDebtSecuritiesMember 		130,308us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionLessThanTwelveMonthsFairValue
/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis
= us-gaap_CorporateDebtSecuritiesMember
Available-for-sale securities, continuous unrealized loss position, twelve months or less, gross unrealized loss (422)p_AvailableforsaleSecuritiesContinuousUnrealizedLossPositionLessthan12MonthsAccumulatedLoss
/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis
= us-gaap_CorporateDebtSecuritiesMember 		(258)p_AvailableforsaleSecuritiesContinuousUnrealizedLossPositionLessthan12MonthsAccumulatedLoss
/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis
= us-gaap_CorporateDebtSecuritiesMember
Available-for-sale securities, continuous unrealized loss position, twelve months or longer, fair value 12,148us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionTwelveMonthsOrLongerFairValue
/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis
= us-gaap_CorporateDebtSecuritiesMember 		0us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionTwelveMonthsOrLongerFairValue
/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis
= us-gaap_CorporateDebtSecuritiesMember
Available-for-sale securities, continuous unrealized loss position, twelve months or longer, gross unrealized loss (22)p_AvailableforsaleSecuritiesContinuousUnrealizedLossPosition12MonthsorLongerAccumulatedLoss
/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis
= us-gaap_CorporateDebtSecuritiesMember 		0p_AvailableforsaleSecuritiesContinuousUnrealizedLossPosition12MonthsorLongerAccumulatedLoss
/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis
= us-gaap_CorporateDebtSecuritiesMember
Available-for-sale securities, continuous unrealized loss position, fair value 204,847us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionFairValue
/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis
= us-gaap_CorporateDebtSecuritiesMember 		130,308us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionFairValue
/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis
= us-gaap_CorporateDebtSecuritiesMember
Available-for-sale securities, continuous unrealized loss position, gross unrealized loss (444)p_AvailableforsaleSecuritiesContinuousUnrealizedLossPositionAccumulatedLoss
/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis
= us-gaap_CorporateDebtSecuritiesMember 		(258)p_AvailableforsaleSecuritiesContinuousUnrealizedLossPositionAccumulatedLoss
/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis
= us-gaap_CorporateDebtSecuritiesMember
U.S. government and government agency debt securities    
Schedule of Available-for-sale Securities [Line Items]    
Available-for-sale securities, continuous unrealized loss position, twelve months or less, fair value 5,240us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionLessThanTwelveMonthsFairValue
/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis
= us-gaap_USGovernmentAgenciesDebtSecuritiesMember 		5,697us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionLessThanTwelveMonthsFairValue
/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis
= us-gaap_USGovernmentAgenciesDebtSecuritiesMember
Available-for-sale securities, continuous unrealized loss position, twelve months or less, gross unrealized loss (9)p_AvailableforsaleSecuritiesContinuousUnrealizedLossPositionLessthan12MonthsAccumulatedLoss
/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis
= us-gaap_USGovernmentAgenciesDebtSecuritiesMember 		(4)p_AvailableforsaleSecuritiesContinuousUnrealizedLossPositionLessthan12MonthsAccumulatedLoss
/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis
= us-gaap_USGovernmentAgenciesDebtSecuritiesMember
Available-for-sale securities, continuous unrealized loss position, twelve months or longer, fair value 0us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionTwelveMonthsOrLongerFairValue
/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis
= us-gaap_USGovernmentAgenciesDebtSecuritiesMember 		0us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionTwelveMonthsOrLongerFairValue
/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis
= us-gaap_USGovernmentAgenciesDebtSecuritiesMember
Available-for-sale securities, continuous unrealized loss position, twelve months or longer, gross unrealized loss 0p_AvailableforsaleSecuritiesContinuousUnrealizedLossPosition12MonthsorLongerAccumulatedLoss
/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis
= us-gaap_USGovernmentAgenciesDebtSecuritiesMember 		0p_AvailableforsaleSecuritiesContinuousUnrealizedLossPosition12MonthsorLongerAccumulatedLoss
/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis
= us-gaap_USGovernmentAgenciesDebtSecuritiesMember
Available-for-sale securities, continuous unrealized loss position, fair value 5,240us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionFairValue
/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis
= us-gaap_USGovernmentAgenciesDebtSecuritiesMember 		5,697us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionFairValue
/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis
= us-gaap_USGovernmentAgenciesDebtSecuritiesMember
Available-for-sale securities, continuous unrealized loss position, gross unrealized loss $ (9)p_AvailableforsaleSecuritiesContinuousUnrealizedLossPositionAccumulatedLoss
/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis
= us-gaap_USGovernmentAgenciesDebtSecuritiesMember 		$ (4)p_AvailableforsaleSecuritiesContinuousUnrealizedLossPositionAccumulatedLoss
/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis
= us-gaap_USGovernmentAgenciesDebtSecuritiesMember