Annual and transition report of foreign private issuers pursuant to Section 13 or 15(d)

Property, Plant and Equipment - Additional Information (Detail)

v2.4.1.9
Property, Plant and Equipment - Additional Information (Detail) (USD $)
 12 Months Ended
Mar. 31, 2015
Mar. 31, 2014
Mar. 31, 2013
Property, Plant and Equipment [Line Items]      
Depreciation expense $ 70,200,000us-gaap_Depreciation $ 61,300,000us-gaap_Depreciation $ 60,000,000us-gaap_Depreciation
Restricted assets value of property, plant and equipment 1,300,000us-gaap_OtherRestrictedAssetsNoncurrent 1,700,000us-gaap_OtherRestrictedAssetsNoncurrent  
Asset impairment charges     16,900,000us-gaap_ImpairmentOfLongLivedAssetsHeldForUse
Plant Facility Level [Member]      
Property, Plant and Equipment [Line Items]      
Asset impairment charges 0us-gaap_ImpairmentOfLongLivedAssetsHeldForUse
/ us-gaap_ImpairedLongLivedAssetsHeldAndUsedByTypeAxis
= jhx_PlantFacilityLevelMember 		0us-gaap_ImpairmentOfLongLivedAssetsHeldForUse
/ us-gaap_ImpairedLongLivedAssetsHeldAndUsedByTypeAxis
= jhx_PlantFacilityLevelMember 		 
Cost of Goods Sold [Member]      
Property, Plant and Equipment [Line Items]      
Asset impairment charges 3,700,000us-gaap_ImpairmentOfLongLivedAssetsHeldForUse
/ us-gaap_IncomeStatementLocationAxis
= us-gaap_CostOfSalesMember 		0us-gaap_ImpairmentOfLongLivedAssetsHeldForUse
/ us-gaap_IncomeStatementLocationAxis
= us-gaap_CostOfSalesMember 		0us-gaap_ImpairmentOfLongLivedAssetsHeldForUse
/ us-gaap_IncomeStatementLocationAxis
= us-gaap_CostOfSalesMember
USA & Europe Fiber Cement [Member]      
Property, Plant and Equipment [Line Items]      
Asset impairment charges     16,900,000us-gaap_ImpairmentOfLongLivedAssetsHeldForUse
/ us-gaap_StatementBusinessSegmentsAxis
= jhx_UnitedStatesOfAmericaAndEuropeFiberCementMember
USA & Europe Fiber Cement [Member] | Plant Facility Level [Member]      
Property, Plant and Equipment [Line Items]      
Asset impairment charges     16,900,000us-gaap_ImpairmentOfLongLivedAssetsHeldForUse
/ us-gaap_ImpairedLongLivedAssetsHeldAndUsedByTypeAxis
= jhx_PlantFacilityLevelMember
/ us-gaap_StatementBusinessSegmentsAxis
= jhx_UnitedStatesOfAmericaAndEuropeFiberCementMember
USA & Europe Fiber Cement [Member] | Buildings, Land and Manufacturing Equipment [Member]      
Property, Plant and Equipment [Line Items]      
Asset impairment charges     4,400,000us-gaap_ImpairmentOfLongLivedAssetsHeldForUse
/ us-gaap_PropertyPlantAndEquipmentByTypeAxis
= jhx_LandBuildingAndEquipmentMember
/ us-gaap_StatementBusinessSegmentsAxis
= jhx_UnitedStatesOfAmericaAndEuropeFiberCementMember
USA & Europe Fiber Cement [Member] | Redundant and Manufacturing Equipment [Member]      
Property, Plant and Equipment [Line Items]      
Asset impairment charges     12,500,000us-gaap_ImpairmentOfLongLivedAssetsHeldForUse
/ us-gaap_PropertyPlantAndEquipmentByTypeAxis
= jhx_RedundantAndManufacturingEquipmentMember
/ us-gaap_StatementBusinessSegmentsAxis
= jhx_UnitedStatesOfAmericaAndEuropeFiberCementMember
USA & Europe Fiber Cement [Member] | Redundant Equipment [Member]      
Property, Plant and Equipment [Line Items]      
Asset impairment charges     2,800,000us-gaap_ImpairmentOfLongLivedAssetsHeldForUse
/ us-gaap_PropertyPlantAndEquipmentByTypeAxis
= jhx_RedundantEquipmentMember
/ us-gaap_StatementBusinessSegmentsAxis
= jhx_UnitedStatesOfAmericaAndEuropeFiberCementMember
USA & Europe Fiber Cement [Member] | Manufacturing Equipment [Member]      
Property, Plant and Equipment [Line Items]      
Asset impairment charges     $ 9,700,000us-gaap_ImpairmentOfLongLivedAssetsHeldForUse
/ us-gaap_PropertyPlantAndEquipmentByTypeAxis
= jhx_ManufacturingEquipmentMember
/ us-gaap_StatementBusinessSegmentsAxis
= jhx_UnitedStatesOfAmericaAndEuropeFiberCementMember