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Restricted Cash and Cash Equivalents - Additional Information (Detail) (USD $) In Millions, unless otherwise specified | Mar. 31, 2015 | Mar. 31, 2014
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Cash and Cash Equivalents [Abstract] |  |
Restricted cash and cash equivalents related to insurance policy | $ 5.0 jhx_RestrictedCashAndCashEquivalentsRelatedToInsurancePolicy | $ 5.0 jhx_RestrictedCashAndCashEquivalentsRelatedToInsurancePolicy

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- Definition Restricted cash and cash equivalents related to insurance policy. + References No definition available. + Details
Name: | jhx_RestrictedCashAndCashEquivalentsRelatedToInsurancePolicy
Namespace Prefix: | jhx_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

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- Details
Name: | us-gaap_CashAndCashEquivalentsAbstract
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration