XML 115 R74.htm IDEA: XBRL DOCUMENT
v3.21.1

Asbestos - Central Estimates, Net of Insurance Recoveries (Details) - Mar. 31, 2021 $ in Millions, $ in Millions | USD ($) | AUD ($)
--- | --- | ---
Central Estimate – Discounted and Inflated |  |
Asbestos Claims [Line Items] |  |
Asbestos liability actuarial estimate | $ 1,339.8 | $ 1,762.6
Range of discounted actuarial estimate, minimum | 990.7 | 1,303.4
Range of discounted actuarial estimate, maximum | 2,229.6 | 2,933.2
Central Estimate – Undiscounted but Inflated |  |
Asbestos Claims [Line Items] |  |
Asbestos liability actuarial estimate | 1,545.8 | 2,033.7
Range of undiscounted actuarial estimate, minimum | 1,119.4 | 1,472.7
Range of undiscounted actuarial estimate, maximum | 2,694.4 | 3,544.8
Central Estimate – Undiscounted and Uninflated |  |
Asbestos Claims [Line Items] |  |
Asbestos liability actuarial estimate | $ 1,027.6 | $ 1,351.9

X
- Definition Asbestos Claims [Line Items] + References No definition available. + Details
Name: | jhx_AsbestosClaimsLineItems
Namespace Prefix: | jhx_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Actuarial estimate of the Asbestos related liabilities, net of insurance recoveries. + References No definition available. + Details
Name: | jhx_AsbestosLiabilityActuarialEstimate
Namespace Prefix: | jhx_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Range of discounted actuarial estimate maximum. + References No definition available. + Details
Name: | jhx_RangeOfDiscountedActuarialEstimateMaximum
Namespace Prefix: | jhx_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Range of discounted actuarial estimate minimum. + References No definition available. + Details
Name: | jhx_RangeOfDiscountedActuarialEstimateMinimum
Namespace Prefix: | jhx_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Range of undiscounted actuarial estimate maximum. + References No definition available. + Details
Name: | jhx_RangeOfUnDiscountedActuarialEstimateMaximum
Namespace Prefix: | jhx_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Range of undiscounted actuarial estimate minimum. + References No definition available. + Details
Name: | jhx_RangeOfUnDiscountedActuarialEstimateMinimum
Namespace Prefix: | jhx_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Details
Name: | us-gaap_BusinessInterruptionLossAxis=jhx_DiscountedAndInflatedMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_BusinessInterruptionLossAxis=jhx_UndiscountedButInflatedMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_BusinessInterruptionLossAxis=jhx_UndiscountedAndUninflatedMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |