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Stockholders Equity Note Disclosure [Line Items]

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Aggregate number of common shares reserved for future issuance.

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Total number of common shares of an entity that have been sold or granted to shareholders (includes common shares that were issued, repurchased and remain in the treasury). These shares represent capital invested by the firm's shareholders and owners, and may be all or only a portion of the number of shares authorized. Shares issued include shares outstanding and shares held in the treasury.

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Unrecognized cost of unvested share-based compensation awards.

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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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The cash inflow from the additional capital contribution to the entity.

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The aggregate amount of noncash, equity-based employee remuneration. This may include the value of stock or unit options, amortization of restricted stock or units, and adjustment for officers' compensation. As noncash, this element is an add back when calculating net cash generated by operating activities using the indirect method.

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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.

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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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The number of non-vested equity-based payment instruments, excluding stock (or unit) options, that validly exist and are outstanding as of the balance sheet date.

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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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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.

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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.

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

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Price of a single share of a number of saleable stocks of a company.

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Percentage of vesting of share-based compensation awards.

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Intrinsic value of equity-based compensation awards vested. Excludes stock and unit options.

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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.

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

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Stockholders' Equity - Additional Information (Detail) - USD ($) $ / shares in Units, $ in Thousands		12 Months Ended
	Jul. 03, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Stockholders Equity Note Disclosure [Line Items]
Common stock, shares issued	2,807,017	43,917,378	43,587,079
Common stock issue price per share	$ 42.75
Exercised number of shares		176,804
Net proceeds from public offering	$ 129,300		$ 129,309
Stock-based compensation expense		$ 10,192	$ 6,747	$ 4,595
Stock options, outstanding		998,226	734,940
Closing price of common stock		$ 52.74
Aggregate intrinsic value of stock options exercised		$ 5,300	$ 5,300	$ 5,000
Weighted average grant date fair value of share-based awards granted		$ 18.90	$ 16.94	$ 14.16
Total fair value of stock options vested		$ 2,300	$ 2,200	$ 1,700
Total unrecognized compensation cost		$ 27,100
Unrecognized compensation cost, weighted average remaining requisite service period		4 years 6 months 10 days
Number of unvested options and restricted stock units		1,195,236
2018 Plan
Stockholders Equity Note Disclosure [Line Items]
Common stock shares reserved for Issuance		2,778,000
Incentive options, vesting period		2,874,751
Employee Stock Option \| Minimum
Stockholders Equity Note Disclosure [Line Items]
Incentive options, vesting period		3 years
Employee Stock Option \| Minimum \| Vest Over Three Year
Stockholders Equity Note Disclosure [Line Items]
Incentive options, vesting percentage		20.00%
Employee Stock Option \| Maximum
Stockholders Equity Note Disclosure [Line Items]
Incentive options, vesting period		5 years
Incentive options, term		10 years
Employee Stock Option \| Maximum \| Vest Over Five Year
Stockholders Equity Note Disclosure [Line Items]
Incentive options, vesting percentage		33.00%
Non-Employee Directors
Stockholders Equity Note Disclosure [Line Items]
Incentive options, vesting period		1 year
Option To Purchase Common Stock
Stockholders Equity Note Disclosure [Line Items]
Stock options, outstanding		998,226	734,940	1,236,586
Restricted Stock Units (RSUs)
Stockholders Equity Note Disclosure [Line Items]
Incentive options, vesting period		5 years
Restricted stock units, outstanding		705,413	505,235
Closing price of common stock		$ 52.74
Aggregate intrinsic value of restricted stock units vested		$ 6,200	$ 4,000	$ 1,700
Weighted average grant date fair value of restricted stock units granted		$ 30.30	$ 26.03	$ 27.25
Total grant date fair value of restricted stock units vested		$ 4,600	$ 4,000	$ 1,500
Unvested Options
Stockholders Equity Note Disclosure [Line Items]
Incentive options, vesting period		5 years
Underwriters \| Common Stock
Stockholders Equity Note Disclosure [Line Items]
Exercised number of shares	421,052
Former president and chief executive officer \| Employee Stock Option
Stockholders Equity Note Disclosure [Line Items]
Stock-based compensation expense				$ 300
Former president and chief executive officer \| Employee Stock Option \| Vested as of April 2016
Stockholders Equity Note Disclosure [Line Items]
Incentive options, vesting percentage				50.00%