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

Income Taxes - Additional Information (Detail)

v3.8.0.1
Income Taxes - Additional Information (Detail)
$ in Millions
 12 Months Ended 48 Months Ended
Mar. 31, 2018
USD ($)
Mar. 31, 2018
AUD ($)
Mar. 31, 2017
USD ($)
Mar. 31, 2016
USD ($)
Mar. 31, 2018
USD ($)
Mar. 31, 2018
AUD ($)
Mar. 31, 2015
USD ($)
Tax Credit Carryforward [Line Items]              
Recognized tax deduction $ 70,700,000 $ 91.4          
Contribution to AICF 102,200,000   $ 91,100,000 $ 62,800,000 $ 369,100,000 $ 456.8  
Foreign tax credit carry-forwards 126,100,000   107,500,000   126,100,000    
Income taxes payable 29,100,000       29,100,000    
Income tax paid, net of refunds 49,100,000            
Total amount of unrecognized tax benefits 700,000   700,000 700,000 700,000   $ 4,900,000
Interest and penalties accrued 0   0 0 0   $ 300,000
Interest and penalties recognized income tax expense $ 0   $ 0 $ 300,000      
Period for the amount of unrecognized tax benefits increase or decrease next twelve months next twelve months          
Blended tax rate (as percent) 31.50% 31.50%          
Income tax expense $ 4,200,000            
Income tax expense from repatriated earnings 31,900,000       31,900,000    
Reduction in net deferred tax liability 27,700,000            
Foreign Tax Credit Carry-Forwards [Member]              
Tax Credit Carryforward [Line Items]              
Foreign tax credit carry-forwards $ 126,100,000       $ 126,100,000    
Percentage of valuation allowance against loss carry-forwards (as percent) 100.00%       100.00%    
Australia [Member]              
Tax Credit Carryforward [Line Items]              
Tax loss carry-forwards $ 18,800,000       $ 18,800,000    
Europe [Member]              
Tax Credit Carryforward [Line Items]              
Tax loss carry-forwards 6,700,000       6,700,000    
Tax loss carry-forwards available to offset future taxable income not subject to expiration 3,200,000       3,200,000    
Operating loss carry-forwards subject to expiration $ 3,500,000       $ 3,500,000