Annual report pursuant to Section 13 and 15(d)

Summary of Significant Accounting Policies - Intangible assets (Details)

v3.19.3
Summary of Significant Accounting Policies - Intangible assets (Details) - USD ($)
$ in Millions
3 Months Ended 12 Months Ended
Jun. 30, 2018
Sep. 30, 2019
Sep. 30, 2018
Sep. 30, 2017
Future amortization expense        
2017   $ 30.6    
2018   29.5    
2019   28.5    
2020   28.1    
2021   27.9    
Components of intangible assets and the related accumulated amortization        
Impairment of Intangible Assets, Indefinite-lived (Excluding Goodwill) $ 4.6   $ 63.4 $ 0.0
Cost   600.1 602.5  
Accumulated amortization   (270.7) (242.8)  
Other Finite-Lived Intangible Assets, Gross   $ 725.6 730.1  
Minimum        
Components of intangible assets and the related accumulated amortization        
Intangible assets amortization period   3 years    
Maximum        
Components of intangible assets and the related accumulated amortization        
Intangible assets amortization period   21 years    
After Tax [Member]        
Components of intangible assets and the related accumulated amortization        
Impairment of Intangible Assets, Indefinite-lived (Excluding Goodwill) $ 3.5      
Trade names        
Components of intangible assets and the related accumulated amortization        
Trade names, indefinite lives   $ 125.5 127.6  
Trade names        
Components of intangible assets and the related accumulated amortization        
Cost   0.2 0.2  
Accumulated amortization   (0.2) (0.2)  
Customer relationships        
Components of intangible assets and the related accumulated amortization        
Cost   464.2 464.5  
Accumulated amortization   (169.2) (148.4)  
Technology, including patents        
Components of intangible assets and the related accumulated amortization        
Cost   76.8 79.6  
Accumulated amortization   (49.4) (45.1)  
Software        
Components of intangible assets and the related accumulated amortization        
Cost   58.7 58.0  
Accumulated amortization   (51.7) (48.9)  
Other        
Components of intangible assets and the related accumulated amortization        
Cost   0.2 0.2  
Accumulated amortization   (0.2) $ (0.2)  
Burnaby Machine & Mill Equipment [Member]        
Components of intangible assets and the related accumulated amortization        
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Finite-Lived Intangibles   14.0    
Burnaby Machine & Mill Equipment [Member] | Trade names        
Components of intangible assets and the related accumulated amortization        
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Finite-Lived Intangibles   1.0    
Burnaby Machine & Mill Equipment [Member] | Customer relationships        
Components of intangible assets and the related accumulated amortization        
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Finite-Lived Intangibles   $ 10.0