Share Based Awards - Unrecognized expense (Details) $ in Millions	9 Months Ended
Sep. 30, 2019 USD ($)
Share Based Compensation Arrangement By Share Based Payment Award
Total, Unrecognized Stock-based Compensation Expense	$ 55.2
Incentive Stock Options
Share Based Compensation Arrangement By Share Based Payment Award
Total, Unrecognized Stock-based Compensation Expense	$ 0.9
Unrecognized stock-based compensation expense, Remaining Weighted-Average Recognition Period (in years)	2 years 8 months 12 days
Restricted stock units
Share Based Compensation Arrangement By Share Based Payment Award
Total, Unrecognized Stock-based Compensation Expense	$ 52.3
Unrecognized stock-based compensation expense, Remaining Weighted-Average Recognition Period (in years)	2 years 10 months 24 days
ESPP
Share Based Compensation Arrangement By Share Based Payment Award
Total, Unrecognized Stock-based Compensation Expense	$ 2.0
Unrecognized stock-based compensation expense, Remaining Weighted-Average Recognition Period (in years)	7 months 6 days

Amount of cost not yet recognized for nonvested award under share-based payment arrangement.

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=116856206&loc=d3e5070-113901

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Weighted-average period over which cost not yet recognized is expected to be recognized for award under share-based payment arrangement, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents reported fact of one year, five months, and thirteen days.

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- Definition

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