Convertible Notes, Net - Summary of Details of Net Book Value of Convertible Note (Detail) - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018
Debt Instrument [Line Items]
Deferred financing costs	$ (25,962)	$ (21,725)
Net book value	612,263	609,911
Convertible Senior Note [Member]
Debt Instrument [Line Items]
Face Value	622,500	622,500
Unamortized discount	(9,552)	(11,740)
Deferred financing costs	(685)	(849)
Net book value	$ 612,263	$ 609,911

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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