XML 47 R31.htm IDEA: XBRL DOCUMENT v3.10.0.1
Convertible Senior Notes - Debt Net of Discounts and Deferred Financing Costs (Detail) - USD ($)
$ in Thousands
Sep. 30, 2018
Dec. 31, 2017
Debt Disclosure [Abstract]    
Principal $ 517,500 $ 517,500
Deferred financing costs (8,663) (9,652)
Debt discount, net (125,190) (138,230)
Net carrying amount 383,647 0
Net carrying amount $ 0 $ 369,618