Share based compensation arrangement by share based payment award individual voting power percentage.

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- Definition

Share based compensation arrangement by share based payment award options grant date fair value.

+ References

No definition available.

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- Definition

Share based compensation arrangement by share based payment award percentage of purchase price for individuals having more than ten percent of combined voting power.

+ References

No definition available.

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- Definition

Share based compensation cash and modification grants related option awards.

+ References

No definition available.

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- Definition

Share based goods and non-employee services transaction shares reserve increase for issuance.

+ References

No definition available.

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- Definition

Unrecognized cost of unvested share-based compensation awards.

+ References

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-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (i)
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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.

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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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-Publisher FASB
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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 weighted average of per share prices paid for shares purchased on the open market for issuance to employees under the plan.

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-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
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- Definition

Maximum number of shares that may be issued in accordance with the plan as a proportion of outstanding capital stock.

+ References

No definition available.

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- Definition

The number of shares purchased on the open market during the period for issuance to employees under the plan.

+ References

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- Definition

The maximum number of shares (or other type of equity) that have been approved for issuance in the equity-based payment transaction.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
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- Definition

Percentage of vesting of share-based compensation awards.

+ References

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-Publisher FASB
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-Topic 718
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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

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
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- Definition

Fair value of options vested. Excludes equity instruments other than options, for example, but not limited to, share units, stock appreciation rights, restricted stock.

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-Publisher FASB
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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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Share-Based Compensation - Additional Information (Details) - USD ($) $ / shares in Units, $ in Millions					1 Months Ended	3 Months Ended
	Jan. 03, 2019	Jan. 02, 2019	Oct. 12, 2018	Jan. 01, 2018	Mar. 31, 2017	Mar. 31, 2019
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Awards vesting period						1 year
Unrecognized compensation cost of options and RSUs						$ 63.2
Expected to be recognized over a weighted average period						2 years 4 months 24 days
Options \| Board Of Directors
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Grants related option awards		$ 3.4
Options \| Elizabeth Barrett
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Option to purchase of ordinary shares	277,432
Exercise price of option to purchase of ordinary shares	$ 47.57
Options \| General and Administrative and Research and Development Expenses \| Board Of Directors
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Estimated fair value of options granted		$ 2.8
Options \| Tranche One
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Vesting percentage						33.00%
Restricted Stock Units (RSUs)
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Awards vesting period						2 years
Restricted Stock Units (RSUs) \| Elizabeth Barrett
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Option to purchase of ordinary shares	317,065
Restricted Stock Units (RSUs) \| Tranche One
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Vesting percentage						33.00%
2017 Equity Incentive Plan
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Maximum number of ordinary share issuable under the 2017 incentive plan					1,400,000	5,600,000
Number of ordinary shares reserved for issuance, percentage						12.00%
Increase in number of ordinary share issuable under the 2017 incentive plan			1,900,000	250,167
Stock Options and Restricted Stock Units (RSUs) \| Elizabeth Barrett
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Fair value	$ 24.1
Plan \| Options
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Awards vesting period						3 years
Combined voting power percentage						10.00%
Ordinary Shares \| 2017 Equity Incentive Plan
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Maximum number of ordinary share issuable under the 2017 incentive plan			3,550,167	1,650,167
Maximum \| Plan \| Options
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Options granted, expected term						10 years
Minimum \| Plan \| Options
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Exercise price of stock options as percentage of fair market value of shares on grant date						100.00%
Stock options exercise price percentage for individuals possesses more than 10% of the combined voter power						110.00%