Annual report pursuant to Section 13 and 15(d)

Financing Arrangements (Details Textual)

v3.6.0.2
Financing Arrangements (Details Textual)
1 Months Ended 12 Months Ended
Aug. 31, 2014
USD ($)
d
$ / shares
shares
Dec. 31, 2016
USD ($)
Dec. 31, 2015
USD ($)
Dec. 31, 2014
USD ($)
Debt Instrument [Line Items]        
Number of consecutive trading days   50 days    
Carrying value of equity component   $ 29,563,000 $ 39,628,000  
Equity component of convertible debt issuance, net of issuance costs   10,065,000 (39,628,000) $ 51,271,000
Warrants to purchase number of shares (shares) | shares 3,264,643      
Exercise price per share of convertible bond hedges | $ / shares $ 75.05      
Payments for convertible bond hedges   0 0 48,143,000
Exercise price per share of warrants (in USD per share) | $ / shares $ 125.08      
Sale of warrants $ 11,600,000     $ 11,638,000
2019 Convertible Senior Notes        
Debt Instrument [Line Items]        
Principal amount outstanding   245,000,000 245,000,000  
Senior Notes        
Debt Instrument [Line Items]        
Payments for convertible bond hedges 48,100,000      
Senior Notes | 2019 Convertible Senior Notes        
Debt Instrument [Line Items]        
Principal amount outstanding 245,000,000.0      
Net proceeds from debt issuance $ 239,300,000      
Convertible debt conversion ratio 0.0133251      
Debt conversion price per share | $ / shares $ 75.05      
Interest on debt instrument (percent) 0.75%      
Carrying value of equity component   51,300,000    
Proceeds from issuance of debt $ 245,000,000      
Discount rate (percent) 5.83%      
Convertible debt, noncurrent $ 192,500,000      
If-converted value of debt in excess of principal   86,700,000    
Debt issuance cost 5,700,000      
Equity component of convertible debt issuance, net of issuance costs 1,200,000      
Unamortized debt issuance costs $ 4,500,000      
Debt issuance costs, net   $ 2,500,000 $ 3,400,000  
Term of debt (duration) 5 years      
Senior Notes | 2019 Convertible Senior Notes | Debt Instrument, Redemption, Period One        
Debt Instrument [Line Items]        
Number of trading days | d 20      
Number of consecutive trading days 30 days      
Stock price trigger threshold (percent) 130.00%      
Senior Notes | 2019 Convertible Senior Notes | Debt Instrument, Redemption, Period Two        
Debt Instrument [Line Items]        
Number of trading days | d 5      
Number of consecutive trading days 10 days      
Debt threshold trigger price (percent) 98.00%