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

Derivative Instruments - Additional Information (Detail)

Derivative Instruments - Additional Information (Detail) (USD $)	12 Months Ended			3 Months Ended	1 Months Ended
	Mar. 31, 2015	Mar. 31, 2014	Mar. 31, 2013	Mar. 31, 2015	Oct. 31, 2013	Dec. 31, 2013
Derivative [Line Items]
Notional amount of interest rate swap contracts	$ 128,600,000invest_DerivativeNotionalAmount	$ 258,700,000invest_DerivativeNotionalAmount		$ 128,600,000invest_DerivativeNotionalAmount
Derivative weighted average fixed interest rate	2.00%			2.00%
Weighted average remaining life of contracts	3 years 7 months 6 days
Interest rate swap contracts included in Accounts Payable	3,100,000jhx_InterestRateSwapFairValueDisclosure	500,000jhx_InterestRateSwapFairValueDisclosure		3,100,000jhx_InterestRateSwapFairValueDisclosure
Unrealized (loss) gain on interest rate swap contracts	(2,600,000)us-gaap_UnrealizedGainLossOnDerivatives	800,000us-gaap_UnrealizedGainLossOnDerivatives	1,800,000us-gaap_UnrealizedGainLossOnDerivatives
Realized loss on settlements of interest rate swap contracts	1,300,000us-gaap_GainLossOnSaleOfDerivatives	600,000us-gaap_GainLossOnSaleOfDerivatives	2,100,000us-gaap_GainLossOnSaleOfDerivatives
Derivatives Not Accounted for As Hedges [Member] \| Cash Flow Hedging [Member]
Derivative [Line Items]
Unrealized gain (loss) associated with the forward contracts not designated as a cash flow hedging arrangement	(2,300,000)	1,800,000		(2,300,000)
Interest Rate Swap Contracts [Member]
Derivative [Line Items]
Notional amount of interest rate swap contracts	125,000,000			125,000,000
Number of additional interest rate swap contracts entered during the year	4			4
Interest Rate Swap Contracts [Member] \| Contact One [Member]
Derivative [Line Items]
Notional amount of interest rate swap contracts	25,000,000			25,000,000
Derivative contracts maturity date				Apr. 01, 2015
Interest Rate Swap Contracts [Member] \| Contract Two [Member]
Derivative [Line Items]
Notional amount of interest rate swap contracts					50,000,000
Derivative term of contract					5 years
Derivative fixed interest rate					2.00%
Interest Rate Swap Contracts [Member] \| Contract Three [Member]
Derivative [Line Items]
Notional amount of interest rate swap contracts						25,000,000
Derivative term of contract						6 years
Derivative fixed interest rate						2.30%
Interest Rate Swap Contracts [Member] \| Contract Four [Member]
Derivative [Line Items]
Notional amount of interest rate swap contracts						25,000,000
Derivative term of contract						4 years
Derivative fixed interest rate						1.50%
Interest Rate Swap Contracts [Member] \| Derivatives Not Accounted for As Hedges [Member]
Derivative [Line Items]
Notional amount of interest rate swap contracts	125,000,000	125,000,000		125,000,000
Foreign Currency Forward Contracts [Member] \| Derivatives Not Accounted for As Hedges [Member]
Derivative [Line Items]
Notional amount of interest rate swap contracts	3,600,000	124,000,000		3,600,000
Unrealized gain classified in other comprehensive income	$ 300,000