Convertible Senior Notes - Debt Net of Discounts and Deferred Financing Costs (Detail) - USD ($) $ in Thousands	Jun. 30, 2018	Dec. 31, 2017
Debt Disclosure [Abstract]
Principal	$ 517,500	$ 517,500
Deferred financing costs	(8,997)	(9,652)
Debt discount, net	(129,618)	(138,230)
Net carrying amount	$ 378,885	$ 369,618

Carrying amount of long-term convertible debt as of the balance sheet date, net of the amount due in the next twelve months or greater than the normal operating cycle, if longer. The debt is convertible into another form of financial instrument, typically the entity's common stock.

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- References

No definition available.

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- Definition

Face (par) amount of debt instrument at time of issuance.

+ References

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-Publisher FASB
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- Definition

Amount, after accumulated amortization, of debt discount (premium).

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- Definition

Amount, after accumulated amortization, of debt issuance costs. Includes, but is not limited to, legal, accounting, underwriting, printing, and registration costs.

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