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Intangible Assets and Goodwill - Additional Information (Details) - USD ($)
12 Months Ended
Dec. 31, 2020
Dec. 31, 2019
Dec. 31, 2018
Schedule Of Finite And Indefinite Lived Intangible Assets [Line Items]      
Gross amount of goodwill of continuing operations $ 517,000,000.0 $ 517,000,000.0  
Accumulated impairment losses 182,400,000 182,400,000  
Amortization 0 0 $ 0
Expected amortization expense, 2021 0    
Expected amortization expense, 2022 0    
Expected amortization expense, 2023 0    
Expected amortization expense, 2024 0    
Expected amortization expense, 2025 0    
Expected amortization expense, thereafter 0    
Tradename      
Schedule Of Finite And Indefinite Lived Intangible Assets [Line Items]      
Intangible assets not subject to amortization $ 29,000,000.0 $ 29,000,000.0