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

Stock-Based Compensation - Additional Information (Detail)

v3.4.0.3
Stock-Based Compensation - Additional Information (Detail)
AUD / shares in Units, AUD in Millions, $ in Millions
1 Months Ended 12 Months Ended
Dec. 09, 2015
shares
Sep. 16, 2015
shares
Sep. 14, 2015
shares
Dec. 09, 2014
shares
Sep. 16, 2014
shares
Jun. 06, 2014
shares
Jun. 07, 2012
shares
Aug. 31, 2007
shares
Nov. 30, 2006
shares
Mar. 31, 2016
USD ($)
shares
Mar. 31, 2016
AUD
AUD / shares
shares
Mar. 31, 2015
USD ($)
shares
Mar. 31, 2015
AUD
shares
Mar. 31, 2014
USD ($)
shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]                            
Unrecognized compensation cost related to stock-based compensation cost | $                   $ 14.0        
Estimated weighted average amortization, period of recognition                   1 year 6 months 1 year 6 months      
Issue of shares authorized                   5,000,000   2,000,000 2,000,000  
Restricted stock units granted                   1,410,560 1,410,560 1,192,225 1,192,225  
Restricted stock units outstanding                   4,049,454   4,008,001 4,008,001 3,883,918
Intrinsic value of stock options exercised | AUD                     AUD 2.9   AUD 3.6  
Excess tax benefits from share-based awards | $                   $ 0.4   $ 1.4   $ 5.6
Closing stock price | AUD / shares                     AUD 17.86      
Restricted stock units vested                   1,219,352 1,219,352 774,675 774,675  
Unvested restricted stock units cancelled                   149,755 149,755 293,467 293,467  
Scorecard LTI - cash settled units granted under the terms of LTIP   566,936     454,179                  
Average closing price period   20 days     20 days                  
Restricted Stock Units Performance Vesting [Member]                            
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]                            
LTI units granted   503,944     403,716   266,627              
Restricted stock units vested             237,239     331,146 331,146      
Restricted stock unit deferred vesting period         3 years                  
Unvested restricted stock units cancelled     82,794                      
Restricted Stock Units Service Vesting [Member]                            
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]                            
Restricted stock units granted 327,354     329,192                    
Restricted stock units vested                   228,481 228,481 222,885 222,885  
Restricted Stock Units (Market Condition) [Member]                            
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]                            
Restricted stock units granted   579,262     459,317                  
Restricted stock units vested                   659,725 659,725 313,865 313,865  
Long Term Incentive Award [Member]                            
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]                            
LTI units granted     288,552     445,141                
Long Term Incentive Award [Member] | Maximum [Member]                            
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]                            
LTI units granted     506,627     716,536                
Average closing price period           10 days                
Long Term Incentive Award [Member] | Maximum [Member] | James Hardie Industries Plc [Member]                            
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]                            
Average closing price period     20 days                      
Long-Term Incentive Plan 2006 [Member]                            
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]                            
Unexercised options expiration year                   10 years 10 years      
Restricted stock units outstanding                   3,347,644        
LTI units granted                   10,163,138 10,163,138      
Granted options               1,016,000 1,132,000          
Options outstanding                   0 0      
2001 Plan [Member]                            
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]                            
Issue of shares authorized                   45,077,100        
Percentage of options exercised after first year                   25.00% 25.00%      
Percentage of options exercised after second year                   25.00% 25.00%      
Percentage of options exercised after third year                   50.00% 50.00%      
Unexercised options expiration year                   10 years 10 years      
Unexercised options expiration days                   90 days 90 days      
Restricted stock units granted                   327,354 327,354 329,192 329,192  
Restricted stock units outstanding                   701,810