Share-based compensation arrangement by share-based payment award number of installments.

No definition available.

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- Definition

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.

+ References

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- Definition

Amount of cost to be recognized for option under share-based payment arrangement.

+ References

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- Definition

Description of service or performance condition required to be met for earning right to award under share-based payment arrangement. Includes, but is not limited to, combination of market, performance or service condition.

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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).

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- Definition

The weighted average fair value at grant date for nonvested equity-based awards issued 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).

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- Definition

Fair value of share-based awards for which the grantee gained the right by satisfying service and performance requirements, to receive or retain shares or units, other instruments, or cash.

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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

Amount of accumulated difference between fair value of underlying shares on dates of exercise and exercise price on options exercised (or share units converted) into shares.

+ References

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- Definition

The weighted average grant-date fair value of options granted during the reporting period as calculated by applying the disclosed option pricing methodology.

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- Definition

Number of options outstanding, including both vested and non-vested options.

+ 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=116856206&loc=d3e5070-113901

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-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (c)(1)(i)-(ii)
-URI http://asc.fasb.org/extlink&oid=116856206&loc=d3e5070-113901

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- Definition

Weighted average price at which grantees can acquire the shares reserved for issuance under the stock option plan.

+ References

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- Definition

Weighted average remaining contractual term for option awards outstanding, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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- Definition

Number of share options (or share units) exercised during the current period.

+ References

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-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
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-Name Accounting Standards Codification
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Stock-Based Compensation - Additional Information (Detail)			3 Months Ended	6 Months Ended
	Oct. 06, 2017 USD ($) shares	Jan. 04, 2016 shares	Dec. 31, 2017 USD ($)	Jun. 30, 2019 USD ($) Installment $ / shares shares	Jun. 30, 2018 $ / shares shares	Dec. 31, 2018 $ / shares shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of options exercised \| shares				118
Aggregate intrinsic value of stock options exercised				$ 622
Options to purchase common stock, outstanding \| shares				4,972,362	4,534,000	4,435,000
Weighted average remaining contractual term				7 years 2 months 12 days	8 years
Weighted average exercise price \| $ / shares				$ 18.23	$ 19.13	$ 19.21
Weighted average grant date fair value of options granted \| $ / shares				$ 8.78	$ 15.35
Unrecognized stock-based compensation expense				$ 23,000,000.0
Unrecognized compensation costs, weighted-average recognition periods				2 years 4 months 24 days
Restricted Stock Units (RSUs) [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share based compensation, number of shares granted \| shares	122,800	189,300		804,381
Grant date fair value of restricted common stock units under performance-based vesting	$ 2,200,000		$ 1,600,000
Unrecognized stock-based compensation expense				$ 12,900,000
Unrecognized compensation costs, weighted-average recognition periods				3 years 3 months 18 days
Weighted average grant date fair value, shares granted, per share \| $ / shares				$ 14.64
Awards vesting right				The RSUs vest in four substantially equal installments on each of the first four anniversaries of the vesting commencement date, subject to the employee’s continued employment with, or services to, the Company on each vesting date.
Restricted Stock Units (RSUs) [Member] \| First Anniversary [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share based compensation, award vesting installments \| Installment				4
Restricted Stock Units (RSUs) [Member] \| Second Anniversary [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share based compensation, award vesting installments \| Installment				4
Restricted Stock Units (RSUs) [Member] \| Third Anniversary [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share based compensation, award vesting installments \| Installment				4
Restricted Stock Units (RSUs) [Member] \| Fourth Anniversary [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share based compensation, award vesting installments \| Installment				4
Restricted Stock Units (RSUs) [Member] \| January 4, 2016 [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unrecognized stock-based compensation expense				$ 600,000
Unrecognized compensation costs, weighted-average recognition periods				2 years