Stock-based compensation - Summary of stock based compensation award granted (Detail) - Employees $ in Thousands	3 Months Ended
Mar. 31, 2019 USD ($) shares
RSUs
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Number of shares granted, RSUs (in shares) \| shares	839,000
Fair value of shares granted \| $	$ 53,184
Non-qualified stock options
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Number of shares granted, options (in shares) \| shares	1,770,000
Fair value of shares granted \| $	$ 33,344

The total grant date fair value of awards made during the period.

No definition available.

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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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- Definition

The number of grants made during the period on other than stock (or unit) option plans (for example, phantom stock or unit plan, stock or unit appreciation rights plan, performance target 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
-Subparagraph (c)(2)(iii)(1)
-URI http://asc.fasb.org/extlink&oid=109197908&loc=d3e5070-113901

+ Details

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- Definition

Gross number of share options (or share units) granted during the period.

+ References

No definition available.

+ Details

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- Details

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