2.4.0.81076 - Disclosure - Stock-based Compensation Plans - Schedule of Share Based Payment Award Stock Options Valuation Assumptions (Detail)truefalsefalse1false USDfalsefalse$eol_PE9760----1210-K0011_STD_366_20120831_0_582032x580470http://www.sec.gov/CIK0000739608duration2011-09-01T00:00:002012-08-31T00:00:00pureStandardhttp://www.xbrl.org/2003/instancepure0iso4217_USD_per_sharesDividehttp://www.xbrl.org/2003/iso4217USDiso4217http://www.xbrl.org/2003/instanceshares0USDUSD$2false USDfalsefalse$eol_PE9760----1210-K0011_STD_365_20110831_0_582032x580470http://www.sec.gov/CIK0000739608duration2010-09-01T00:00:002011-08-31T00:00:00pureStandardhttp://www.xbrl.org/2003/instancepure0iso4217_USD_per_sharesDividehttp://www.xbrl.org/2003/iso4217USDiso4217http://www.xbrl.org/2003/instanceshares0USDUSD$1false 0truefalsetruefalsefalsefalsefalsefalsefalse1falsefalsefalse00falsefalsefalse2falsefalsefalse00falsefalsefalse1false USDtruefalse$eol_PE9760----1210-K0011_STD_366_20120831_0_582032x580470http://www.sec.gov/CIK0000739608duration2011-09-01T00:00:002012-08-31T00:00:00falsefalseStock Options [Member]us-gaap_AwardTypeAxisxbrldihttp://xbrl.org/2006/xbrldius-gaap_StockOptionsMemberus-gaap_AwardTypeAxisexplicitMemberpureStandardhttp://www.xbrl.org/2003/instancepure0iso4217_USD_per_sharesDividehttp://www.xbrl.org/2003/iso4217USDiso4217http://www.xbrl.org/2003/instanceshares0USDUSD$nanafalse0Stock Options [Member]2true 3us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItemsus-gaap_truenadurationfalsefalsefalsefalsefalsefalsefalsefalseterseLabel1falsefalsefalse00falsefalsefalse2falsefalsefalse00falsefalsefalsexbrli:stringItemTypestringfalse0Share-based Compensation Arrangement by Share-based Payment Award [Line Items]3false 4us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedVolatilityRateus-gaap_truenadurationfalsefalsefalsefalsefalsefalsefalsefalseterseLabel1truetruefalse0.680.68falsefalsefalse2truetruefalse0.710.71falsefalsefalsenum:percentItemTypepureThe estimated measure of the percentage by which a share price is expected to fluctuate during a period. Volatility also may be defined as a probability-weighted measure of the dispersion of returns about the mean. The volatility of a share price is the standard deviation of the continuously compounded rates of return on the share over a specified period. That is the same as the standard deviation of the differences in the natural logarithms of the stock prices plus dividends, if any, over the period.Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (f)(2)(ii) -URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 123R -Paragraph A240 -Subparagraph e(2)(b) -LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy. false0Expected volatility4false 4us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardFairValueAssumptionsExpectedTerm1us-gaap_truenadurationfalsefalsefalsefalsefalsefalsefalsefalseterseLabel1falsefalsefalse004 years 10 months 24 daysfalsefalsefalse2falsefalsefalse004 years 3 months 18 daysfalsefalsefalsexbrli:durationItemTypenaExpected term of share-based compensation awards, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SAB TOPIC 14.D.2) -URI http://asc.fasb.org/extlink&oid=6793087&loc=d3e301413-122809 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (f)(2)(i) -URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Staff Accounting Bulletin (SAB) -Number Topic 14 -Section D -Subsection 2 false0Expected life (years)5false 4us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRateMinimumus-gaap_truenadurationfalsefalsefalsefalsefalsefalsefalsefalseterseLabel1truetruefalse0.0050.005falsefalsefalse2truetruefalse0.0110.011falsefalsefalsenum:percentItemTypepureThe minimum risk-free interest rate assumption that is used in valuing an option on its own shares.No definition available.false0Interest rate, Minimum6false 4us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRateMaximumus-gaap_truenadurationfalsefalsefalsefalsefalsefalsefalsefalseterseLabel1truetruefalse0.0110.011falsefalsefalse2truetruefalse0.0280.028falsefalsefalsenum:percentItemTypepureThe maximum risk-free interest rate assumption that is used in valuing an option on its own shares.No definition available.false0Interest rate, Maximum7false 4us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedDividendRateus-gaap_truenadurationfalsefalsefalsefalsefalsefalsefalsefalseterseLabel1truetruefalse0.000.00falsefalsefalse2truetruefalse0.000.00falsefalsefalsenum:percentItemTypepureThe estimated dividend rate (a percentage of the share price) to be paid (expected dividends) to holders of the underlying shares over the option's term.Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (f)(2)(iii) -URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 123R -Paragraph A240 -Subparagraph e(2)(c) -LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy. false0Dividend yield8false 4us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageGrantDateFairValueus-gaap_truenadurationfalsefalsefalsefalsefalsefalsefalsefalseterseLabel1truefalsefalse3.133.13USD$falsetruefalse2truefalsefalse3.623.62USD$falsetruefalsenum:perShareItemTypedecimalThe weighted average grant-date fair value of options granted during the reporting period as calculated by applying the disclosed option pricing methodology.Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 123R -Paragraph A240 -Subparagraph c(1) -LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy. Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (d)(1) -URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901 false3Weighted-average fair values, Per sharefalseStock-based Compensation Plans - Schedule of Share Based Payment Award Stock Options Valuation Assumptions (Detail) (Stock Options [Member], USD $)UnKnownUnKnownNoRoundingUnKnowntruefalsefalseSheethttp://www.penx.com/taxonomy/role/DisclosureStockbasedCompensationPlansScheduleOfShareBasedPaymentAwardStockOptionsValuationAssumptions28