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Debt - Additional Information (Details)
$ / shares in Units, shares in Millions
1 Months Ended 3 Months Ended 12 Months Ended
May 01, 2020
USD ($)
$ / shares
shares
Apr. 23, 2020
USD ($)
May 31, 2020
USD ($)
shares
Aug. 31, 2018
USD ($)
day
$ / shares
shares
Dec. 31, 2020
USD ($)
day
Dec. 31, 2020
USD ($)
$ / shares
Dec. 31, 2019
USD ($)
Dec. 31, 2018
USD ($)
Debt Instrument [Line Items]                
Proceeds from convertible debt           $ 222,799,000 $ 0 $ 223,121,000
Letter of Credit                
Debt Instrument [Line Items]                
Long-term line of credit         $ 8,100,000 $ 8,100,000    
2023 Notes                
Debt Instrument [Line Items]                
Strike price (in dollars per share) | $ / shares           $ 41.59    
2023 Notes | Call Option                
Debt Instrument [Line Items]                
Strike price (in dollars per share) | $ / shares       $ 41.59        
Cap price (in dollars per share) | $ / shares $ 63.98              
Option indexed to issuer's equity (in shares) | shares       5.5        
Equity component of convertible debt, subsequent adjustments       $ 26,900,000        
2025 Notes                
Debt Instrument [Line Items]                
Strike price (in dollars per share) | $ / shares           $ 61.02    
2025 Notes | Call Option                
Debt Instrument [Line Items]                
Strike price (in dollars per share) | $ / shares 61.02              
Cap price (in dollars per share) | $ / shares $ 93.88              
Option indexed to issuer's equity (in shares) | shares 3.8              
Equity component of convertible debt, subsequent adjustments $ 27,300,000              
Credit Agreement | London Interbank Offered Rate (LIBOR)                
Debt Instrument [Line Items]                
Basis spread on variable rate   2.50%            
Credit Agreement | Base Rate                
Debt Instrument [Line Items]                
Basis spread on variable rate   0.00%            
Credit Agreement | Minimum | London Interbank Offered Rate (LIBOR)                
Debt Instrument [Line Items]                
Basis spread on variable rate   1.00%            
Credit Agreement | Revolving Credit Facility                
Debt Instrument [Line Items]                
Current borrowing capacity   $ 30,000,000.0 $ 50,000,000.0          
Credit sublimit   15,000,000.0            
Fee amount   $ 400,000            
Commitment fee percentage   0.20%            
Credit Agreement | Letter of Credit                
Debt Instrument [Line Items]                
Maximum borrowing capacity   $ 70,000,000.0            
Convertible Debt                
Debt Instrument [Line Items]                
Carrying amount of equity component         99,026,000 $ 99,026,000 99,026,000  
Debt issuance costs, net         $ 8,059,000 $ 8,059,000    
Convertible Debt | Debt Covenant One                
Debt Instrument [Line Items]                
Threshold trading days | day       20        
Threshold consecutive trading days | day       30        
Threshold percentage of stock price trigger       130.00%        
Convertible Debt | Debt Covenant Two                
Debt Instrument [Line Items]                
Threshold trading days | day       5        
Threshold percentage of stock price trigger       98.00%        
Convertible Debt | Debt Covenant Three                
Debt Instrument [Line Items]                
Threshold percentage of stock price trigger       130.00%        
Redemption price, percentage       100.00%        
Convertible Debt | 2023 Notes                
Debt Instrument [Line Items]                
Face amount       $ 230,000,000.0        
Stated interest percentage       1.25% 1.25% 1.25%    
Proceeds from convertible debt       $ 223,100,000        
Carrying amount of equity component       53,800,000 $ 52,194,000 $ 52,194,000 52,194,000  
Debt issuance costs, net       6,900,000 $ 3,009,000 $ 3,009,000 4,032,000  
Liability component       5,300,000        
Convertible, issuance costs of equity component       $ 1,600,000        
Interest rate, effective percentage       7.36%        
Equity component of convertible debt, subsequent adjustments       $ 26,910,000        
Convertible Debt | 2023 Notes | Call Option                
Debt Instrument [Line Items]                
Option indexed to issuer's equity (in shares) | shares       5.5        
Convertible Debt | 2023 Notes | Debt Covenant Three                
Debt Instrument [Line Items]                
Threshold trading days | day       20        
Threshold consecutive trading days | day       30        
Redemption price, percentage       100.00%        
Convertible Debt | 2025 Notes                
Debt Instrument [Line Items]                
Face amount       $ 230,000,000.0        
Stated interest percentage       2.25% 2.25% 2.25%    
Proceeds from convertible debt       $ 222,800,000        
Carrying amount of equity component 48,300,000       $ 46,832,000 $ 46,832,000 $ 46,832,000  
Debt issuance costs, net 7,200,000       $ 5,050,000 $ 5,050,000    
Liability component 5,700,000              
Convertible, issuance costs of equity component $ 1,500,000              
Interest rate, effective percentage       7.85%        
Equity component of convertible debt, subsequent adjustments       $ 27,255,000        
Convertible Debt | 2025 Notes | Call Option                
Debt Instrument [Line Items]                
Option indexed to issuer's equity (in shares) | shares     3.8          
Convertible Debt | The Notes | Debt Covenant Three                
Debt Instrument [Line Items]                
Threshold trading days | day         20      
Threshold consecutive trading days | day         30      
Threshold percentage of stock price trigger         130.00%