Annual report pursuant to Section 13 and 15(d)

Debt - Summary of Debt (Details)

v3.20.4
Debt - Summary of Debt (Details) - USD ($)
$ in Thousands
Dec. 31, 2020
Nov. 19, 2020
Aug. 27, 2020
Dec. 31, 2019
Debt Instrument [Line Items]        
Outstanding principal $ 4,724,978      
Deferred financing costs (2,017)     $ (2,056)
Total 4,816,233     572,944
Debt classified as current (31,026)      
Total long-term debt 4,785,207     572,944
2.75% Exchangeable Senior Debentures due 2050        
Debt Instrument [Line Items]        
Outstanding principal 575,000      
Carrying value $ 608,804      
Interest rate (as a percent) 2.75%   2.75%  
1.25% Exchangeable Senior Debentures due 2050        
Debt Instrument [Line Items]        
Outstanding principal $ 825,000      
Carrying value $ 836,971      
Interest rate (as a percent) 1.25% 1.25%    
1.75% Exchangeable Senior Debentures due 2046        
Debt Instrument [Line Items]        
Outstanding principal $ 14,536      
Carrying value $ 26,350      
Interest rate (as a percent) 1.75%      
Senior notes        
Debt Instrument [Line Items]        
Outstanding principal $ 600,000      
Carrying value 635,683      
Line of credit        
Debt Instrument [Line Items]        
Outstanding principal 704,000      
Carrying value 704,000      
Wells Fargo note payable        
Debt Instrument [Line Items]        
Outstanding principal 6,442      
Carrying value 6,442      
SPV | Margin Loan Facility        
Debt Instrument [Line Items]        
Outstanding principal 2,000,000      
Carrying value $ 2,000,000     $ 575,000