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Summary of Significant Accounting Policies - Goodwill and Other Intangible Assets (Details)
12 Months Ended
Dec. 31, 2020
USD ($)
segment
Dec. 31, 2019
USD ($)
Dec. 31, 2018
USD ($)
Goodwill [Line Items]      
Number of reportable segments | segment 2    
Goodwill impairment     $ 1,300,000
Depreciation $ 12,600,000 $ 12,000,000.0 15,800,000
Asset impairment charges, related to restructuring activities 0 4,600,000  
Impairment credit / (charges) $ 0 (200,000) 5,900,000
Asset impairment charges, related to fair value adjustment in divestiture of business     3,400,000
Sub161 Pty Limited | Equity Method Investee      
Goodwill [Line Items]      
VIEs ownership percentage 26.40%    
Discontinued operations | Superform Aluminum Superplastic      
Goodwill [Line Items]      
Goodwill impairment     $ 1,300,000
Impairment credit / (charges)   $ 5,200,000  
Measurement Input, Long-term Revenue Growth Rate      
Goodwill [Line Items]      
Goodwill impairment test, measurement input 0.018    
Measurement Input, Discount Rate | Minimum      
Goodwill [Line Items]      
Goodwill impairment test, measurement input 0.080    
Measurement Input, Discount Rate | Maximum      
Goodwill [Line Items]      
Goodwill impairment test, measurement input 0.090