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v2.4.1.9

Commitments and Contingencies (Details) In Millions, unless otherwise specified | 6 Months Ended |  |
--- | --- | --- | ---
Mar. 31, 2015 USD ($) | Mar. 31, 2015 CAD | Mar. 31, 2014 USD ($) | Dec. 31, 2014 Prior To 1995 [member] USD ($) | Mar. 31, 2015 From 2000 to 2005 [Member] USD ($)
Loss Contingency, Damages Sought, Value |  | 10.0 us-gaap_LossContingencyDamagesSoughtValue |  |  |
Walter Energy tax assessment | 34.0 mwa_AmountOfTaxClaimedForIssuesCurrentlyInDispute |  |  | 33.0 mwa_AmountOfTaxClaimedForIssuesCurrentlyInDispute / mwa_CommitmentsAndContingenciesTimeFrameAxis = mwa_PriorTo1995Member | 82.2 mwa_AmountOfTaxClaimedForIssuesCurrentlyInDispute / mwa_CommitmentsAndContingenciesTimeFrameAxis = mwa_From2000To2005Member
Walter Energy tax assessment prior to 1995 related to timing | 21.0 mwa_AmountOfTaxClaimedForIssuesAtFormerAffiliateRelatingToTimingOfDeductionsOnly |  |  |  |
Amount payable pending completion of an IRS audit | 11.6 mwa_AmountReceivablePendingCompletionOfAnIRSAudit |  |  |  |
Proceeds from Sale of Productive Assets | $ 4.8 us-gaap_ProceedsFromSaleOfProductiveAssets |  | $ 0.3 us-gaap_ProceedsFromSaleOfProductiveAssets |  |

X
- Definition Amount of tax claimed for issues at a former affiliate relating to timing of deductions only. + References No definition available. + Details
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- Definition Total amount of tax claimed for issues at a former affiliate. + References No definition available. + Details
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Namespace Prefix: | mwa_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
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X
- Definition The receivable from a former affiliate expected to be collected after their final settlement with a taxing authority. + References No definition available. + Details
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Namespace Prefix: | mwa_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition The value (monetary amount) of the award the plaintiff seeks in the legal matter. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 450 -SubTopic 20 -Section 50 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=25496072&loc=d3e14326-108349 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 450 -SubTopic 20 -Section 50 -Paragraph 4 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=25496072&loc=d3e14435-108349 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 450 -SubTopic 20 -Section 50 -Paragraph 9 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=25496072&loc=d3e14557-108349 + Details
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- Definition The cash inflow from the sale of property, plant and equipment (capital expenditures), software, and other intangible assets. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Glossary Investing Activities -URI http://asc.fasb.org/extlink&oid=6516133 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 230 -SubTopic 10 -Section 45 -Paragraph 12 -Subparagraph (c) -URI http://asc.fasb.org/extlink&oid=31042434&loc=d3e3179-108585 + Details
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