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

Goodwill and Other Intangible Assets Goodwill and Other Intangible Assets (Details)

v3.19.1
Goodwill and Other Intangible Assets Goodwill and Other Intangible Assets (Details) - USD ($)
$ in Millions
12 Months Ended
Mar. 31, 2019
Mar. 31, 2018
Mar. 31, 2017
Goodwill [Line Items]      
Amortization $ 6.1 $ 0.9 $ 0.8
Impairment 2.6 $ 0.0 $ 0.0
Other Businesses      
Goodwill [Line Items]      
Impairment 2.2    
North America Fiber Cement      
Goodwill [Line Items]      
Impairment $ 0.4