Debt - Convertible Notes (Details)
1 Months Ended 12 Months Ended
May 31, 2014
USD ($)
Dec. 31, 2020
USD ($)
$ / shares
Dec. 31, 2019
USD ($)
Debt Instrument [Line Items]      
Extinguishment of Debt, Amount     $ 2,000,000.0
Stated interest rate   3.64%  
Unamortized deferred financing costs   $ 18,515,000 17,549,000
Convertible Senior Notes      
Debt Instrument [Line Items]      
Unamortized discount   $ 1,000,000.0 6,500,000
Stated interest rate   3.75%  
Equity component of the conversion feature   $ 55,100,000 55,100,000
Unamortized deferred financing costs   300,000 2,100,000
Convertible Senior Notes | Convertible Senior Notes Due 2019      
Debt Instrument [Line Items]      
Extinguishment of Debt, Amount     $ 402,500,000
Aggregate principal amount of debt $ 402,500,000    
Stated interest rate 2.875%    
Debt instrument, maturity date May 15, 2019    
Convertible Senior Notes | Convertible Senior Notes Due 2021      
Debt Instrument [Line Items]      
Extinguishment of Debt, Amount   $ 154,600,000  
Aggregate principal amount of debt $ 345,000,000.0    
Stated interest rate 3.75%    
Debt conversion ratio   17.4458  
Anti-dilutive cash dividends, exceeding (in USD per share) | $ / shares   $ 0.73026