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Stock Plans - Options Vesting (Details)	12 Months Ended
	Dec. 31, 2020
Monthly Percentage
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Percentage of awards vesting	2.08%
Quarterly Percentage After First Anniversary
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Percentage of awards vesting	6.25%
Upon Achievement of Performance Objectives
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Percentage of awards vesting	33.33%
Annual Percentage After Achievement of Performance Objectives
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Percentage of awards vesting	33.33%
2015 Plan | Stock options | First Anniversary
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Percentage of awards vesting	25.00%
2010 Plan | Stock options | Second Anniversary
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Percentage of awards vesting	50.00%
2000 and 2006 Stock incentive plans | Stock options | First Anniversary
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Percentage of awards vesting	25.00%

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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

Percentage of vesting of award under share-based payment arrangement.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (a)(1)
-URI http://asc.fasb.org/extlink&oid=120381028&loc=d3e5070-113901

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