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

Accumulated Other Comprehensive Loss (Detail)

v3.19.1
Accumulated Other Comprehensive Loss (Detail) - USD ($)
$ in Millions
 12 Months Ended
Mar. 31, 2019
Mar. 31, 2018
Mar. 31, 2017
Accumulated Other Comprehensive Income (Loss) [Line Items]      
Other Comprehensive Income (Loss), Cash Flow Hedge, Gain (Loss), Reclassification, after Tax   $ 0.0 $ 0.0
Currency translation adjustments   0.9 (3.0)
AOCI Attributable to Parent, Net of Tax [Roll Forward]      
Beginning balance $ (221.5) (212.2) (225.2)
Other comprehensive loss 29.0    
Ending balance 974.4 (221.5) (212.2)
Accumulated Other Comprehensive Loss [Member]      
AOCI Attributable to Parent, Net of Tax [Roll Forward]      
Beginning balance (1.3) (2.2) 0.8
Ending balance (30.3) (1.3) $ (2.2)
Cash Flow Hedges [Member]      
Accumulated Other Comprehensive Income (Loss) [Line Items]      
Other Comprehensive Income (Loss), Cash Flow Hedge, Gain (Loss), Reclassification, after Tax 0.1    
AOCI Attributable to Parent, Net of Tax [Roll Forward]      
Beginning balance 0.3    
Ending balance 0.2 0.3  
Foreign Currency Translation Adjustments [Member]      
Accumulated Other Comprehensive Income (Loss) [Line Items]      
Currency translation adjustments (28.9)    
AOCI Attributable to Parent, Net of Tax [Roll Forward]      
Beginning balance (1.6)    
Ending balance $ (30.5) $ (1.6)