Impact of COVID-19 - Balance Sheet, Cash Flow and Liquidity Narrative (Details) - USD ($)
12 Months Ended
Dec. 31, 2020
Mar. 31, 2021
Jun. 30, 2020
May 12, 2020
Mar. 30, 2020
Unusual or Infrequent Item, or Both [Line Items]          
Liquidity   $ 1,940,800,000      
ATM Program          
Unusual or Infrequent Item, or Both [Line Items]          
Number of shares sold (in shares) 9,000,000        
Consideration received on sale of shares $ 156,700,000        
Common Stock | Public Offering          
Unusual or Infrequent Item, or Both [Line Items]          
Number of shares sold (in shares) 20,125,000        
Consideration received on sale of shares $ 192,400,000        
8.00% senior secured notes due in 2025          
Unusual or Infrequent Item, or Both [Line Items]          
Stated interest rate   8.00%      
8.00% Senior Secured Notes Due 2025 | 8.00% senior secured notes due in 2025          
Unusual or Infrequent Item, or Both [Line Items]          
Principal amount $ 850,000,000        
Stated interest rate 8.00% 8.00%      
4.75% Convertible Senior Notes | Convertible debt          
Unusual or Infrequent Item, or Both [Line Items]          
Principal amount $ 175,000,000.0     $ 175,000,000.0  
Stated interest rate       4.75%  
2022 Revolving Credit Facility | Line of Credit | Revolving credit facilities          
Unusual or Infrequent Item, or Both [Line Items]          
Line of credit facility, maximum borrowing capacity $ 180,000,000.0        
Revolving credit facility due in 2024 | Line of Credit | Revolving credit facilities          
Unusual or Infrequent Item, or Both [Line Items]          
Line of credit facility, maximum borrowing capacity   $ 240,000,000.0 $ 180,000,000.0   $ 110,000,000.0
Line of credit facility, remaining borrowing capacity   $ 60,000,000.0 $ 60,000,000.0