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v2.4.1.9

Operating Segment Information and Concentrations of Risk - Additional Information (Detail) | 12 Months Ended
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Mar. 31, 2015 Customer | Mar. 31, 2014 | Mar. 31, 2013
Segment Reporting [Abstract] |  |  |
Percentage of net sales individually account for two major customers | 10.00%jhx_PercentageOfNetSalesPerCustomerMaximum | 10.00%jhx_PercentageOfNetSalesPerCustomerMaximum | 10.00%jhx_PercentageOfNetSalesPerCustomerMaximum
Number of major customers | 2 jhx_NumberOfCustomer |  |
Accounts receivable major customer percentage | 14.00%jhx_EntityWideAccountsReceivableMajorCustomerPercentage | 14.00%jhx_EntityWideAccountsReceivableMajorCustomerPercentage |
Percentage of net sales | 25.00%jhx_SalesOutsideDomesticCountryAsPercentageOfNetSales | 27.00%jhx_SalesOutsideDomesticCountryAsPercentageOfNetSales | 30.00%jhx_SalesOutsideDomesticCountryAsPercentageOfNetSales

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- Definition Entity wide accounts receivable major customer percentage. + References No definition available. + Details
Name: | jhx_EntityWideAccountsReceivableMajorCustomerPercentage
Namespace Prefix: | jhx_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | instant

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- Definition Number Of Customer + References No definition available. + Details
Name: | jhx_NumberOfCustomer
Namespace Prefix: | jhx_
Data Type: | xbrli:integerItemType
Balance Type: | na
Period Type: | duration

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- Definition Percentage Of Net Sales Per Customer Maximum + References No definition available. + Details
Name: | jhx_PercentageOfNetSalesPerCustomerMaximum
Namespace Prefix: | jhx_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | duration

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- Definition Sales outside the United States as a percentage of net sales. + References No definition available. + Details
Name: | jhx_SalesOutsideDomesticCountryAsPercentageOfNetSales
Namespace Prefix: | jhx_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | duration

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