Unrecognized cost of unvested share-based compensation awards.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (i)
-URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901

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- Definition

Weighted average period over which unrecognized compensation is expected to be recognized for equity-based compensation plans, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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- Definition

The total recognized tax benefit related to compensation cost for equity-based payment arrangements recognized in income during the period.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (h)(1)(i)
-URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901

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- Definition

Sum of the allocated, committed-to-be-released and suspense shares of the entity held by the plan.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 40
-Section 50
-Paragraph 1
-Subparagraph (d)
-URI http://asc.fasb.org/extlink&oid=65895303&loc=d3e17540-113929

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- Definition

Fair value of share-based awards for which the grantee gained the right by satisfying service and performance requirements, to receive or retain shares or units, other instruments, or cash.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (d)(2)
-URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901

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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

Number of additional shares authorized for issuance under an established share-based compensation plan.

+ References

No definition available.

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- Definition

Common stock, closing price

+ References

No definition available.

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- Definition

Restricted stock units with performance condition

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No definition available.

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- Definition

Share-based compensation arrangement by share-based payment award, equity instruments other than options, nonvested, aggregate intrinsic value

+ References

No definition available.

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Employee Benefits And Stock-Based Compensation (Stock Based Compensation to Modifications) (Narrative) (Details) - USD ($) $ / shares in Units, $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Number of Additional Shares Authorized	2,500,000
Employee Stock Ownership Plan (ESOP), Shares in ESOP	3,500,000
Closing price of Verisign's stock	$ 114.44
Income Tax Expense [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Income tax benefit on stock-based compensation	$ 12.5	$ 17.7	$ 16.0
Restricted Stock Units (RSUs) [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total unrecognized compensation cost	$ 77.5
Weighted-average period of recognition for unrecognized compensation cost (in years)	2 years 6 months
Aggregate intrinsic value of unvested RSUs	$ 181.7
Fair values of vested RSUs	$ 75.9	$ 70.5	$ 59.8
Performance Shares [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Restricted stock units with performance condition	400,000
Minimum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Restricted stock units with performance condition	0
Maximum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Restricted stock units with performance condition	800,000