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

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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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Unrecognized cost of unvested options awarded to employees as compensation.

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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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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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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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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 share instruments newly issued under a share-based compensation plan.

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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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Stock-Based Compensation - Additional Information (Detail) - USD ($)	1 Months Ended		3 Months Ended			9 Months Ended
	Dec. 31, 2016	Sep. 30, 2016	Sep. 30, 2017	Mar. 31, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Grant date fair value of options granted, per share						$ 3.18	$ 2.42
Grant date fair value of options vested						$ 2,900,000	$ 1,900,000
Aggregate intrinsic value of option exercised						1,800,000	1,700,000
Unrecognized compensation cost			$ 9,400,000			$ 9,400,000
Weighted average period for recognition of compensation costs						2 years 10 months 25 days
Stock based compensation expenses			984,000		$ 954,000	$ 2,766,000	2,199,000
Stock-based compensation expense capitalized			$ 0		$ 0	$ 0	$ 0
Restricted Stock Units (RSUs)
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
RSUs Granted						0
Stock based compensation expenses						$ 0
Restricted Stock Units (RSUs) \| Board of Directors
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
RSUs Granted		112,578
Grant date fair value of RSUs vested, per share		$ 3.58
Restricted Stock Units (RSUs) \| Executive Officers
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
RSUs Granted	18,017
RSUs Released				18,017
Restricted Stock Units (RSUs) \| Consultant
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
RSUs Granted	20,645