Annual report pursuant to Section 13 and 15(d)

Debt Instruments - Narrative (Details)

v3.3.1.900
Debt Instruments - Narrative (Details)
$ / shares in Units, shares in Millions
1 Months Ended 11 Months Ended 12 Months Ended
Dec. 09, 2015
USD ($)
day
$ / shares
$ / unit
shares
Dec. 31, 2015
USD ($)
May. 31, 2011
USD ($)
Dec. 31, 2013
USD ($)
Dec. 31, 2015
USD ($)
Dec. 31, 2014
USD ($)
Debt Instruments            
Payments for capped call transactions       $ 0 $ 43,160,000 $ 0
Debt instrument, conversion price | $ / shares $ 16.42          
Line of credit            
Debt Instruments            
Maximum borrowings available   $ 120,000,000     120,000,000  
Credit facility financial covenant, minimum liquidity   10,000,000.0 $ 5,000,000.0      
Line of credit facility, unused capacity, commitment fee percentage     0.375%      
Interest rate, minimum     2.00%      
Interest rate, maximum     2.25%      
Outstanding borrowings   0     0 0
Available borrowing capacity   118,900,000     118,900,000 58,900,000
Debt issuance cost         $ 400,000  
Credit facility term remaining         4 years  
Amortization of debt issuance costs       $ 200,000 $ 200,000 200,000
Line of credit | LIBOR            
Debt Instruments            
Variable interest rate base     LIBO      
Line of credit | LIBOR | Minimum            
Debt Instruments            
Margin     2.00%      
Line of credit | LIBOR | Maximum            
Debt Instruments            
Margin     2.25%      
Line of credit | Alternate base rate            
Debt Instruments            
Variable interest rate base     alternate base rate      
Line of credit | Alternate base rate | Minimum            
Debt Instruments            
Margin     1.00%      
Line of credit | Alternate base rate | Maximum            
Debt Instruments            
Margin     1.25%      
Letter of credit            
Debt Instruments            
Maximum borrowings available   15,000,000.0     15,000,000.0  
Outstanding amount   $ 1,100,000     $ 1,100,000 $ 1,100,000
Convertible debt | Notes            
Debt Instruments            
Aggregate principal amount $ 345,000,000.0          
Interest rate 1.75%          
Net proceeds from sale of debt $ 336,500,000          
Payments for capped call transactions $ 43,200,000          
Debt instrument, conversion ratio 0.060905          
Debt instrument, conversion price | $ / shares $ 16.42          
Debt instrument, redemption price, percentage of principal 100.00%          
Debt conversion, maximum number of shares of common stock convertible by Notes | shares 27.3          
Value of debt $ 233,500,000          
Carrying amount of equity component reported in additional paid-in-capital 103,000,000          
Debt fees and expenses $ 2,600,000          
Initial cap price (in dollars per share) | $ / unit 25.26          
Convertible debt | Notes | Redemption, period 1            
Debt Instruments            
Debt instrument, threshold percentage of stock price trigger 130.00%          
Debt instrument, threshold trading days | day 20          
Debt instrument, threshold consecutive trading days 30 days          
Debt instrument, threshold notice trading days | day 5          
Convertible debt | Notes | Redemption, period 2            
Debt Instruments            
Debt instrument, threshold percentage of stock price trigger 130.00%          
Debt instrument, threshold trading days | day 20          
Debt instrument, threshold consecutive trading days 30 days          
Convertible debt | Notes | Redemption, period 3            
Debt Instruments            
Debt instrument, threshold note trading days | day 5          
Debt instrument, threshold consecutive note trading days 10 days          
Debt instrument, threshold percentage of note price trigger 98.00%