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

Business Combinations - Summary of Intangible Assets Acquired (Details)

v3.19.1
Business Combinations - Summary of Intangible Assets Acquired (Details) - USD ($)
$ in Millions
 12 Months Ended
Mar. 31, 2019
Mar. 31, 2018
Apr. 03, 2018
Finite-Lived Intangible Assets [Line Items]      
Acquired Finite-lived Intangible Assets, Weighted Average Useful Life 11 years 8 months 6 years 1 month  
Fermacell      
Finite-Lived Intangible Assets [Line Items]      
Intangible assets     $ 187.0
Trade name [Member] | Fermacell      
Finite-Lived Intangible Assets [Line Items]      
Intangible assets     126.8
Customer relationships [Member]      
Finite-Lived Intangible Assets [Line Items]      
Acquired Finite-lived Intangible Assets, Weighted Average Useful Life 12 years 0 years  
Customer relationships [Member] | Fermacell      
Finite-Lived Intangible Assets [Line Items]      
Intangible assets     57.8
Acquired Finite-lived Intangible Assets, Weighted Average Useful Life 13 years    
Other intangible assets [Member]      
Finite-Lived Intangible Assets [Line Items]      
Acquired Finite-lived Intangible Assets, Weighted Average Useful Life 7 years 6 months 6 years 1 month  
Other intangible assets [Member] | Fermacell      
Finite-Lived Intangible Assets [Line Items]      
Intangible assets     $ 2.4
Minimum [Member]      
Finite-Lived Intangible Assets [Line Items]      
Acquired Finite-lived Intangible Assets, Weighted Average Useful Life 2 years    
Minimum [Member] | Fermacell      
Finite-Lived Intangible Assets [Line Items]      
Acquired Finite-lived Intangible Assets, Weighted Average Useful Life 2 years    
Maximum [Member]      
Finite-Lived Intangible Assets [Line Items]      
Acquired Finite-lived Intangible Assets, Weighted Average Useful Life 13 years    
Maximum [Member] | Fermacell      
Finite-Lived Intangible Assets [Line Items]      
Acquired Finite-lived Intangible Assets, Weighted Average Useful Life 13 years