Employee Benefit Plans (Narrative) (Details) - USD ($) shares in Millions, $ in Millions	3 Months Ended
Mar. 31, 2019	Jan. 01, 2019
Stock Options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total unrecognized compensation	$ 7.4
Weighted-average period of recognition of stock based compensation	2 years 1 month 6 days
RSUs
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total unrecognized compensation	$ 41.1
Weighted-average period of recognition of stock based compensation	2 years 3 months
2016 Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Options granted, vesting term (in years)	4 years
Additional shares authorized (in shares)		3.1
Number of shares reserved for future grant (in shares)	3.0
ESPP
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Price at which employees could purchase stock semi-annually, percent of fair market value on purchase date	85.00%
General duration of each offering period	6 months
ESPP \| ESPP
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares reserved for future grant (in shares)	0.7
Maximum percentage of compensation contributed by employees	10.00%

Share-based Compensation Arrangement by Share-based Payment Award, Duration of Each Offering Period

No definition available.

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- Definition

Aggregate number of common shares reserved for future issuance.

+ References

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)
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

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- Definition

Unrecognized cost of unvested share-based compensation awards.

+ 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 (i)
-URI http://asc.fasb.org/extlink&oid=109197908&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.

+ References

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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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-Topic 718
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-Section 50
-Paragraph 2
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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

The highest percentage of annual salary that an employee is permitted to utilize with respect to the plan.

+ 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
-URI http://asc.fasb.org/extlink&oid=109197908&loc=d3e5070-113901

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- Definition

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

Purchase price of common stock expressed as a percentage of its fair value.

+ References

No definition available.

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