Components of Convertible Senior Notes (Detail) - USD ($) $ in Thousands	Jul. 01, 2018	Dec. 31, 2017	Dec. 12, 2016
Debt Instrument
Net carrying amount of convertible debt	$ 372,897	$ 365,987
1.25% Convertible Senior Unsecured Notes Due December 15, 2023
Debt Instrument
Debt principal	460,000	460,000	$ 460,000
Unamortized discount	87,103	94,013
Net carrying amount of convertible debt	$ 372,897	$ 365,987

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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- Definition

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

+ References

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- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

No definition available.

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- Definition

Amount of unamortized debt discount (premium) and debt issuance costs.

+ References

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-Publisher FASB
-Name Accounting Standards Codification
-Topic 470
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