Annual report pursuant to Section 13 and 15(d)

Subsequent Events (Details)

v3.10.0.1
Subsequent Events (Details)
1 Months Ended 12 Months Ended
Dec. 27, 2018
USD ($)
Feb. 28, 2019
USD ($)
d
$ / shares
Dec. 31, 2018
USD ($)
Jan. 31, 2013
USD ($)
d
$ / shares
Rate
Dec. 31, 2018
USD ($)
Rate
Dec. 31, 2017
Rate
Dec. 31, 2016
Rate
Feb. 01, 2019
USD ($)
Nov. 08, 2018
USD ($)
Subsequent Event [Line Items]                  
Credit line capacity | $     $ 197,189,000   $ 197,189,000        
Payment of SEC penalty | $ $ 100,000   $ 100,000            
Convertible Debt | Subsequent Event                  
Subsequent Event [Line Items]                  
Interest rate of notes payable   4.50%              
Convertible Senior Notes Due 2025 | Convertible Debt | Subsequent Event                  
Subsequent Event [Line Items]                  
Debt face amount | $   $ 200,000,000.0              
Conversion ratio   0.2367424              
Conversion price (in dollars per share) | $ / shares   $ 4.22              
Notes Due February 1, 2033 | 2033 Senior Notes                  
Subsequent Event [Line Items]                  
Debt face amount | $       $ 175,000,000.0          
Interest rate of notes payable     3.00% 3.00% 3.00% 3.00% 3.00%    
Convertible debt, threshold percentage of stock price trigger       130.00%          
Conversion ratio | Rate       14.14827% 14.14827% 14.14827% 14.14827%    
Conversion price (in dollars per share) | $ / shares       $ 7.07          
Equivalent redemption price       100.00%          
Notes Due February 1, 2033 | 2033 Senior Notes | Subsequent Event                  
Subsequent Event [Line Items]                  
Debt repurchase amount | $               $ 28,800,000  
Minimum | Notes Due February 1, 2033 | 2033 Senior Notes                  
Subsequent Event [Line Items]                  
Threshold trading days | d       20          
Maximum | Notes Due February 1, 2033 | 2033 Senior Notes                  
Subsequent Event [Line Items]                  
Number of consecutive trading days applicable conversion price | d       30          
Debt Instrument, Redemption, Period One | Convertible Senior Notes Due 2025 | Convertible Debt | Subsequent Event                  
Subsequent Event [Line Items]                  
Convertible debt, threshold percentage of stock price trigger   130.00%              
Equivalent redemption price   100.00%              
Debt Instrument, Redemption, Period One | Notes Due February 1, 2033 | 2033 Senior Notes                  
Subsequent Event [Line Items]                  
Equivalent redemption price       100.00%          
Debt Instrument, Redemption, Period One | Minimum | Convertible Senior Notes Due 2025 | Convertible Debt | Subsequent Event                  
Subsequent Event [Line Items]                  
Threshold trading days | d   20              
Debt Instrument, Redemption, Period One | Maximum | Convertible Senior Notes Due 2025 | Convertible Debt | Subsequent Event                  
Subsequent Event [Line Items]                  
Number of consecutive trading days applicable conversion price | d   30              
Debt Instrument, Redemption, Period Two | Convertible Senior Notes Due 2025 | Convertible Debt | Subsequent Event                  
Subsequent Event [Line Items]                  
Convertible debt, threshold percentage of stock price trigger   98.00%              
Debt Instrument, Redemption, Period Two | Minimum | Convertible Senior Notes Due 2025 | Convertible Debt | Subsequent Event                  
Subsequent Event [Line Items]                  
Threshold trading days | d   5              
Debt Instrument, Redemption, Period Two | Maximum | Convertible Senior Notes Due 2025 | Convertible Debt | Subsequent Event                  
Subsequent Event [Line Items]                  
Number of consecutive trading days applicable conversion price | d   5              
Debt Instrument, Redemption, Period Three | Convertible Senior Notes Due 2025 | Convertible Debt | Subsequent Event                  
Subsequent Event [Line Items]                  
Convertible debt, threshold percentage of stock price trigger   130.00%              
Equivalent redemption price   100.00%              
Debt Instrument, Redemption, Period Three | Minimum | Convertible Senior Notes Due 2025 | Convertible Debt | Subsequent Event                  
Subsequent Event [Line Items]                  
Threshold trading days | d   20              
Debt Instrument, Redemption, Period Three | Maximum | Convertible Senior Notes Due 2025 | Convertible Debt | Subsequent Event                  
Subsequent Event [Line Items]                  
Number of consecutive trading days applicable conversion price | d   30              
Line of Credit | Unsecured Debt                  
Subsequent Event [Line Items]                  
Interest rate of notes payable                 10.00%
Credit line capacity | $                 $ 60,000,000
Dr Frost | Line of Credit | Unsecured Debt                  
Subsequent Event [Line Items]                  
Credit line capacity | $                 $ 60,000,000
Dr Frost                  
Subsequent Event [Line Items]                  
Payment of SEC penalty | $     $ 5,500,000