Summary of Significant Accounting Policies - Stock-based Compensation (Details)	12 Months Ended
Dec. 31, 2018
Restricted stock units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock options vesting period (in years)	4 years
Performance shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Compensation expense recognized, vesting term (in years)	3 years
2012 Employee Stock Purchase Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Offering period	6 months

Share-based Compensation Arrangement by Share-based Payment Award, Purchase Offering Period

No definition available.

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- Definition

Estimated period over which an employee is required to provide service in exchange for the equity-based payment award, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

+ 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=109197908&loc=d3e5070-113901

+ Details

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- Definition

Period which an employee's right to exercise an award is no longer contingent on satisfaction of either a service condition, market condition or a performance condition, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

+ 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.

+ Details

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