• Filing Date: 2018-03-07
  • Form Type: 10-K
  • Description: Annual report
v3.8.0.1
Long-Term Debt (Convertible Senior Notes) - Additional Information (Detail)
$ / shares in Units, $ in Thousands
1 Months Ended 3 Months Ended 12 Months Ended
Apr. 03, 2017
USD ($)
Mar. 03, 2017
USD ($)
Jan. 31, 2015
$ / shares
Dec. 31, 2017
USD ($)
$ / shares
Dec. 31, 2017
USD ($)
d
$ / shares
Dec. 31, 2016
USD ($)
Mar. 31, 2016
USD ($)
Dec. 31, 2013
USD ($)
Debt Instrument [Line Items]                
Debt instrument, face amount       $ 260,061 $ 260,061 $ 147,985    
Debt extinguishment costs         $ (743)      
3.875% Convertible Senior Notes [Member]                
Debt Instrument [Line Items]                
Debt instrument, stated interest rate       3.875% 3.875%      
Debt conversion date       2019        
Debt instrument, face amount       $ 89,990 $ 89,990 89,990 $ 89,990 $ 103,000
Aggregate amount of debt repurchased             $ 13,010  
Convertible debt, conversion ratio         16.2172      
Convertible debt, conversion price | $ / shares       $ 61.66 $ 61.66      
Debt instrument, effective interest rate       8.30% 8.30%      
Debt discount, remaining amortization period         1 year 2 months 12 days      
3.875% Convertible Senior Notes [Member] | Convertible Debt Instrument Conversion Period Two [Member] | Minimum [Member]                
Debt Instrument [Line Items]                
Cash dividends on common stock | $ / shares     $ 0.275          
4.25% Convertible Senior Notes [Member]                
Debt Instrument [Line Items]                
Debt instrument, stated interest rate 4.25% 4.25%   4.25% 4.25%      
Debt conversion date       2037        
Debt instrument, face amount   $ 143,750   $ 143,750 $ 143,750      
Proceeds from senior convertible notes net   138,775            
Debt issuance and transaction costs   $ 4,975            
Convertible debt, conversion ratio         16.2635      
Convertible debt, conversion price | $ / shares       $ 61.49 $ 61.49      
Debt instrument, effective interest rate       7.60% 7.60%      
Debt discount, remaining amortization period         4 years 2 months 12 days      
Debt Instrument effective Rate         5.40%      
Debt Instrument term         20 years      
4.25% Convertible Senior Notes [Member] | Debt Instrument, Redemption, Period One [Member]                
Debt Instrument [Line Items]                
Debt instrument put date         Mar. 01, 2022      
4.25% Convertible Senior Notes [Member] | Debt Instrument, Redemption, Period Two [Member]                
Debt Instrument [Line Items]                
Debt instrument put date         Mar. 01, 2027      
4.25% Convertible Senior Notes [Member] | Debt Instrument, Redemption, Period Three [Member]                
Debt Instrument [Line Items]                
Debt instrument put date         Mar. 01, 2032      
Convertible Senior Notes [Member]                
Debt Instrument [Line Items]                
Debt instrument, face amount       $ 233,740 $ 233,740 89,990    
Convertible debt, conversion debt description         The holders of the Convertible Senior Notes may convert all or a portion of their Convertible Senior Notes during specified periods as follows: (1) during any calendar quarter commencing after the calendar quarter ending on the dates specified in each respective indenture, if the last reported sale price of the Company’s common stock for at least 20 trading days during the period of 30 consecutive trading days ending on the last trading day of the immediately preceding calendar quarter is greater than 130% of the conversion price on each applicable trading day; (2) during the five business-day period after any ten consecutive trading-day period in which the trading price per $1 principal amount of the Convertible Senior Notes is less than 98% of the product of the last reported sale price and the conversion rate on each such trading day; (3) if specified corporate events, including a change in control, occur; or (4) at any time on or after the dates specified in each respective indenture.      
Convertible debt, threshold trading days | d         20      
Convertible debt, threshold consecutive trading days | d         30      
Convertible debt, threshold percentage of stock trigger price         130.00%      
Convertible Senior Notes [Member] | Convertible Debt Instrument Conversion Period Two [Member]                
Debt Instrument [Line Items]                
Convertible debt, threshold consecutive trading days | d         10      
Convertible debt, threshold trading days         5 days      
Convertible debt, threshold percentage of stock trigger price         98.00%      
Senior Notes [Member]                
Debt Instrument [Line Items]                
Debt instrument, face amount           $ 40,250    
Extinguishment of debt $ 40,805              
Fixed annual rate of interest 8.00%     8.00% 8.00%      
Unamortized debt issuance costs $ 743              
Accrued and unpaid interest $ 555              
Debt extinguishment costs         $ 743