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

Summary of Significant Accounting Policies - Additional Information (Detail)

v3.8.0.1
Summary of Significant Accounting Policies - Additional Information (Detail)
$ in Millions
 12 Months Ended
Mar. 31, 2018
USD ($)
director
shares
Mar. 31, 2017
USD ($)
shares
Mar. 31, 2016
USD ($)
shares
Apr. 01, 2018
USD ($)
Summary Of Significant Accounting Policies [Line Items]        
Ownership interest rate percentage (as percent) 100.00%      
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%      
Deferred income taxes assets $ 29.9 $ 26.9    
Deferred tax assets, valuation allowance $ 129.6 $ 110.4    
Accounting Standards Update 2016-16 [Member] | Scenario, Forecast [Member] | Subsequent Event [Member]        
Summary Of Significant Accounting Policies [Line Items]        
Deferred income taxes assets       $ 1,390.0
Deferred tax assets, valuation allowance       150.0
364-Day Term Loan Facility [Member]        
Summary Of Significant Accounting Policies [Line Items]        
Debt instrument, term 364 days      
Restricted Stock Units (RSUs) [Member]        
Summary Of Significant Accounting Policies [Line Items]        
Potential diluted common shares outstanding | shares 0 0 0  
Contingent Shares Not Expected To Vest [Member]        
Summary Of Significant Accounting Policies [Line Items]        
Potential diluted common shares outstanding | shares 1,600,000 1,800,000 1,300,000  
AICF Funding [Member]        
Summary Of Significant Accounting Policies [Line Items]        
Ownership interest rate percentage (as percent) 0.00%      
Retained Earnings [Member] | Accounting Standards Update 2016-16 [Member] | Scenario, Forecast [Member] | Subsequent Event [Member]        
Summary Of Significant Accounting Policies [Line Items]        
Cumulative effect of new accounting principle in period of adoption       $ 1,240.0
AICF Funding [Member]        
Summary Of Significant Accounting Policies [Line Items]        
Number of directors appointed by Company | director 3      
AICF Funding [Member] | New South Wales, Australia [Member]        
Summary Of Significant Accounting Policies [Line Items]        
Number of directors appointed by NSW government | director 2      
Other Accrued Liabilities [Member]        
Summary Of Significant Accounting Policies [Line Items]        
Prior period reclassification adjustment   $ (2.7) $ (4.0)  
Income Tax Payable [Member]        
Summary Of Significant Accounting Policies [Line Items]        
Prior period reclassification adjustment   $ 2.7 $ 4.0