2.2.0.25falsefalse41206 - Disclosure - Derivatives and Other Financial Instruments (Schedule of Impact on Earnings from Interest Rate Swaps) (Details)truefalseIn Millionsfalse1falsefalseUSDfalsefalse1/1/2011 - 3/31/2011 USD ($) USD ($) / shares $Duration_1_1_2011_To_3_31_2011http://www.sec.gov/CIK0001452575duration2011-01-01T00:00:002011-03-31T00:00:00Unit12Standardhttp://www.xbrl.org/2003/iso4217USDiso42170Unit1Standardhttp://www.xbrl.org/2003/instancesharesxbrli0Unit14Dividehttp://www.xbrl.org/2003/iso4217USDiso4217http://www.xbrl.org/2003/instancesharesxbrli0Unit13Standardhttp://www.xbrl.org/2003/instancepurexbrli0USDUSD$2falsefalseUSDfalsefalse1/1/2010 - 3/31/2010 USD ($) USD ($) / shares $Duration_1_1_2010_To_3_31_2010http://www.sec.gov/CIK0001452575duration2010-01-01T00:00:002010-03-31T00:00:00Unit12Standardhttp://www.xbrl.org/2003/iso4217USDiso42170Unit1Standardhttp://www.xbrl.org/2003/instancesharesxbrli0Unit14Dividehttp://www.xbrl.org/2003/iso4217USDiso4217http://www.xbrl.org/2003/instancesharesxbrli0Unit13Standardhttp://www.xbrl.org/2003/instancepurexbrli0USDUSD$2true0us-gaap_SummaryOfDerivativeInstrumentsAbstractus-gaaptruenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00falsefalsefalsefalsefalse2falsefalsefalse00falsefalsefalsefalsefalseOtherxbrli:stringItemTypestringNo definition available.falsefalseDerivatives and Other Financial Instruments3false0us-gaap_ChangeInUnrealizedGainLossOnFairValueHedgingInstrumentsus-gaaptruedebitdurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalseverboselabel1truefalsefalse-3000000-3.0falsetruefalsefalsefalse2truefalsefalse-4700000-4.7falsetruefalsefalsefalseMonetaryxbrli:monetaryItemTypemonetaryAmount of the increase or decrease in fair value during the period of derivative or nonderivative instruments designated as fair value hedging instruments. Recognized in earnings and offsets the gain (loss) on the hedged item to the extent that the fair value hedge is determined to be effective.Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 133 -Paragraph 45 -Subparagraph a(1) falsefalseRecognized in interest expense4false0mjn_AmortizationOfBasisAdjustmentForTerminatedInterestRateSwapsmjnfalsedebitdurationAmortization of basis adjustment for terminated interest rate swapsfalsefalsefalsefalsefalsefalsefalsefalsefalsefalseverboselabel1truefalsefalse-500000-0.5falsefalsefalsefalsefalse2falsefalsefalse00falsefalsefalsefalsefalseMonetaryxbrli:monetaryItemTypemonetaryAmortization of basis adjustment for terminated interest rate swapsNo authoritative reference available.falsefalseAmortization of basis adjustment for terminated interest rate swaps recognized in interest expense5false0us-gaap_DerivativeInstrumentsGainLossRecognizedInIncomeNetus-gaaptruecreditdurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsetruenegatedtotal1truefalsefalse-3500000-3.5falsetruefalsefalsefalse2truefalsefalse-4700000-4.7falsetruefalsefalsefalseMonetaryxbrli:monetaryItemTypemonetaryThe amount of net gains and losses recognized in income during the period on derivative instruments designated and qualifying as hedging instruments in fair value hedges and related hedged items designated and qualifying in fair value hedges, on derivative instruments designated and qualifying as hedging instruments in cash flow hedges, and on derivative instruments not designated as hedging instruments.Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 133 -Paragraph 205G Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 133 -Paragraph 44C -Subparagraph b truefalseTotal increase (decrease) in interest expense24Derivatives and Other Financial Instruments (Schedule of Impact on Earnings from Interest Rate Swaps) (Details) (USD $)HundredThousandsUnKnownUnKnownUnKnownfalsetrue