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Asbestos - Summary of Net Unfunded AFFA Liability, Net of Tax (Parenthetical) (Detail) AUD in Millions, $ in Millions | 12 Months Ended |
--- | --- | ---
Mar. 31, 2016 USD ($) | Mar. 31, 2016 AUD | Mar. 31, 2015 USD ($)
Insurance [Abstract] |  |  |
Income tax payable | $ 19.6 |  | $ 19.2
Other assets and liabilities of AICF | (1.0) |  | $ (1.5)
Asbestos claims paid | $ 113.9 | AUD 154.7 |

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- Definition Australian tax deduction available to be taken by the Company resulting from the Company's previous contributions to AICF. + References No definition available. + Details
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Namespace Prefix: | jhx_
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- Definition Liability for asbestos claims net claim paid. + References No definition available. + Details
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Namespace Prefix: | jhx_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
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- Definition Net Other Assets And Liabilities Of Asbestos Injuries Compensation Fund + References No definition available. + Details
Name: | jhx_NetOtherAssetsAndLiabilitiesOfAsbestosInjuriesCompensationFund
Namespace Prefix: | jhx_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

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- References No definition available. + Details
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Namespace Prefix: | us-gaap_
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Balance Type: | na
Period Type: | duration