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

Summary of Significant Accounting Policies - Additional Information (Detail)

v3.7.0.1
Summary of Significant Accounting Policies - Additional Information (Detail)
shares in Millions, $ in Millions
 12 Months Ended
Mar. 31, 2017
Directors
shares
Mar. 31, 2016
USD ($)
shares
Mar. 31, 2015
shares
Summary Of Significant Accounting Policies [Line Items]      
Ownership interest rate percentage 100.00%    
Number of directors appointed by Company | Directors 3    
Number of Directors appointed by NSW Government | Directors 2    
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 | shares 1.8 1.3 1.7
ASU No. 2015-03 [Member] | Prepaid Expenses and Other Current Assets [Member]      
Summary Of Significant Accounting Policies [Line Items]      
Debt issuance cost | $   $ 1.6  
ASU No. 2015-03 [Member] | Other Assets [Member]      
Summary Of Significant Accounting Policies [Line Items]      
Debt issuance cost | $   $ 9.4  
AICF Funding [Member]      
Summary Of Significant Accounting Policies [Line Items]      
Ownership interest rate percentage 0.00%