Quarterly report pursuant to Section 13 or 15(d)

Debt Instruments - Convertible Debt Offering Due 2023 (Details)

v3.10.0.1
Debt Instruments - Convertible Debt Offering Due 2023 (Details)
$ / shares in Units, shares in Millions
May 24, 2018
USD ($)
day
$ / shares
shares
Dec. 09, 2015
USD ($)
$ / shares
Jun. 30, 2018
USD ($)
$ / shares
Convertible senior notes due 2023      
Debt Instrument [Line Items]      
Debt fees and expenses $ 1,700,000    
Convertible debt | Convertible senior notes due 2020      
Debt Instrument [Line Items]      
Extinguishment of debt 192,900,000    
Aggregate principal amount 157,400,000 $ 345,000,000.0  
Interest rate   1.75% 1.75%
Debt instrument, conversion ratio   0.060905  
Debt instrument, conversion price (in dollars per share) | $ / shares   $ 16.42 $ 16.42
Value of debt   $ 233,500,000 $ 145,700,000
Carrying amount of equity component reported in additional paid-in-capital   (103,000,000.0)  
Debt fees and expenses   $ 2,600,000  
Convertible debt | Convertible senior notes due 2023      
Debt Instrument [Line Items]      
Aggregate principal amount $ 192,900,000    
Interest rate 1.75%   1.75%
Debt instrument, conversion ratio 104.4778    
Debt instrument, conversion price (in dollars per share) | $ / shares $ 9.57   $ 9.57
Debt instrument, redemption price, percentage of principal 100.00%    
Debt conversion, maximum number of shares of common stock convertible by notes (shares) | shares 27.2    
Value of debt $ 124,300,000   $ 208,100,000
Carrying amount of equity component reported in additional paid-in-capital (67,300,000)    
Debt fees and expenses $ 3,200,000    
Convertible debt | Convertible senior notes due 2023 | Redemption period 1      
Debt Instrument [Line Items]      
Debt instrument, threshold percentage of stock price trigger 130.00%    
Debt instrument, threshold trading days | day 20    
Debt instrument, threshold consecutive trading days | day 30    
Convertible debt | Convertible senior notes due 2023 | Redemption period 2      
Debt Instrument [Line Items]      
Debt instrument, threshold percentage of stock price trigger 130.00%    
Debt instrument, threshold trading days | day 20    
Debt instrument, threshold consecutive trading days | day 30    
Convertible debt | Convertible senior notes due 2023 | Redemption period 3      
Debt Instrument [Line Items]      
Debt instrument, threshold note trading days | day 5    
Debt instrument, threshold consecutive note trading days 10 days    
Debt instrument, threshold principle amount of note trigger $ 1,000    
Debt instrument, threshold percentage of note price trigger 98.00%