Common Stock, Preferred Stock and Equity Plans - Stock and Option Plans (Details)	12 Months Ended
Dec. 31, 2018 vote shares	Dec. 31, 2017 shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common stock, shares authorized (shares)	500,000,000	500,000,000
Common stock, number of votes per share \| vote	1
Preferred stock, shares authorized (shares)	1,000,000	1,000,000
Preferred stock, shares issued (shares)	0	0
Preferred stock, shares outstanding (shares)	0	0
Awards outstanding (shares)	12,506,101
Additional awards authorized for grant (shares)	14,737,360
2013 Stock and Option Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Awards outstanding (shares)	10,735,107
Additional awards authorized for grant (shares)	14,737,360
Additional shares authorized (shares)	8,000,000	6,750,000
2006 Stock and Option Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Awards outstanding (shares)	1,770,994
Additional awards authorized for grant (shares)	0
Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expiration period	10 years

The maximum number of common shares permitted to be issued by an entity's charter and bylaws.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02(29))
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The maximum number of nonredeemable preferred shares (or preferred stock redeemable solely at the option of the issuer) permitted to be issued by an entity's charter and bylaws.

+ References

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Total number of nonredeemable preferred shares (or preferred stock redeemable solely at the option of the issuer) issued to shareholders (includes related preferred shares that were issued, repurchased, and remain in the treasury). May be all or portion of the number of preferred shares authorized. Excludes preferred shares that are classified as debt.

+ References

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Aggregate share number for all nonredeemable preferred stock (or preferred stock redeemable solely at the option of the issuer) held by stockholders. Does not include preferred shares that have been repurchased.

+ References

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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.

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No definition available.

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

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The difference between the maximum number of shares (or other type of equity) authorized for issuance under the plan (including the effects of amendments and adjustments), and the sum of: 1) the number of shares (or other type of equity) already issued upon exercise of options or other equity-based awards under the plan; and 2) shares (or other type of equity) reserved for issuance on granting of outstanding awards, net of cancellations and forfeitures, if applicable.

+ References

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- Definition

Period from grant date that an equity-based award expires, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

+ References

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Common Stock, Votes Per Each Share

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Share-Based Compensation Arrangement By Share-based Payment Award, Equity Instruments Outstanding, Number

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