Common stock shares authorized subject to approval.

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- Definition

Excess tax benefit from share based compensation.

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- Definition

Represents the expense recognized during the period arising from equity-based compensation arrangements (for example, shares of stock, unit, stock options or other equity instruments) with employees, directors and certain consultants qualifying for treatment as employees.

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- Definition

Face amount or stated value per share of common stock.

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- Definition

The maximum number of common shares permitted to be issued by an entity's charter and bylaws.

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- Definition

Unrecognized cost of unvested share-based compensation awards.

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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

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.

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No definition available.

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- Definition

The number of shares into which fully or partially vested stock options outstanding as of the balance sheet date can be currently converted under the option plan.

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- Definition

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

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- Definition

Amount of stock repurchase plan authorized.

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Total cost of shares repurchased divided by the total number of shares repurchased.

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Number of shares that have been repurchased during the period and are being held in treasury.

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Equity impact of the cost of common and preferred stock that were repurchased during the period. Recorded using the cost method.

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Stock-Based Compensation and Stockholder's Equity - Additional Information (Details) - USD ($)	3 Months Ended		12 Months Ended
	Mar. 31, 2019	Mar. 31, 2018	Dec. 31, 2018	Nov. 30, 2018	Jun. 30, 2018	May 31, 2018
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Common stock, shares authorized	200,000,000		200,000,000			100,000,000
Common stock, par value per share	$ 0.00001		$ 0.00001
Common stock, shares authorized subject to approval					200,000,000
Stock-based compensation expense	$ 4,948,000	$ 3,679,000
Reduction in income tax expense related to stock based compensation	$ 2,600,000	3,400,000
Options outstanding, shares	135,956
Options exercisable, shares	119,505
Restricted Stock Units (RSUs)
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Unrecognized compensation expense	$ 28,600,000	$ 16,600,000
Recognition period of unrecognized compensation cost	1 year 10 months 24 days	1 year 6 months 29 days
Common Stock
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Stock repurchase program, authorized amount				$ 150,000,000
Common stock shares acquired	0		223,823
Common stock acquired value			$ 9,100,000
Common stock acquired average price per share			$ 40.80