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

Summary of Significant Accounting Policies - Additional Information (Detail)

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Summary of Significant Accounting Policies - Additional Information (Detail) (USD $)
In Millions, unless otherwise specified
12 Months Ended
Mar. 31, 2014
Directors
Mar. 31, 2013
Mar. 31, 2012
Mar. 31, 2006
Accounting Policies [Abstract]        
Asset impairment charges    $ 16.9 $ 14.3  
Advertising expense 9.5 8.9 8.6  
Equity awards vested percentage after first year 25.00%      
Equity awards vested percentage after second year 25.00%      
Equity awards vested percentage after third year 50.00%      
Potential diluted common shares outstanding 1.9 4.4 11.1  
Asbestos provision net       $ 715.6
Ownership percentage 100.00% 100.00% 100.00%  
Number of directors appointed by Company 3      
Directors appointed by NSW Government 2      
Period of asbestos-related research and education contributions 10 years      
Long-term debt, repayment date Nov. 01, 2030