Convertible Notes, Net - Summary of Details of Net Book Value of Convertible Note (Detail) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Debt Instrument [Line Items]
Deferred financing costs	$ (21,725)	$ (16,681)
Net book value	609,911	563,911
Convertible Senior Note [Member]
Debt Instrument [Line Items]
Face Value	622,500	575,000
Unamortized discount	(11,740)	(10,279)
Deferred financing costs	(849)	(810)
Net book value	$ 609,911	$ 563,911

Including the current and noncurrent portions, carrying value as of the balance sheet date of a written promise to pay a note, initially due after one year or beyond the operating cycle if longer, which can be exchanged for a specified amount of one or more securities (typically common stock), at the option of the issuer or the holder.

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