XML 104 R89.htm IDEA: XBRL DOCUMENT v3.10.0.1
Debt - Summary of Interest Expense Recognized Related to Notes (Detail) - Convertible Senior Notes - USD ($)
$ in Thousands
12 Months Ended
Dec. 31, 2018
Dec. 31, 2017
Dec. 31, 2016
Nov. 30, 2018
Dec. 31, 2014
Convertible Senior Notes Due 2023          
Debt Instrument, Redemption [Line Items]          
0.75% coupon $ 281        
Amortization of debt issuance costs 52        
Amortization of debt discount 392        
Interest expense on 2019 Notes $ 725        
Interest rate of debt, stated percentage 2.25%     2.25%  
Convertible Senior Notes Due 2019          
Debt Instrument, Redemption [Line Items]          
0.75% coupon $ 2,595 $ 2,580 $ 2,588    
Amortization of debt issuance costs 1,505 1,536 1,350    
Amortization of debt discount 13,812 12,937 12,400    
Interest expense on 2019 Notes $ 17,912 $ 17,053 $ 16,338    
Interest rate of debt, stated percentage 0.75%       0.75%