Number of anniversaries of grant date upon which restricted stock units vest.

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Number of former employees hired.

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The amount of adjustment to stockholders' equity associated with an employee's income tax withholding obligation as part of a net-share settlement of a share-based award.

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- Definition

The compensation expense recognized during the period pertaining to the deferred compensation arrangement.

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Aggregate carrying value as of the balance sheet date of the liabilities for stock option plans and other equity-based compensation arrangements payable within one year (or the operating cycle, if longer).

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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 number of equity-based payment instruments, excluding stock (or unit) options, that were forfeited during the reporting period.

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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

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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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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- Definition

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

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Percentage of vesting of share-based compensation awards.

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- Definition

For net-share settlement of share-based awards when the employer settles employees' income tax withholding obligations, this element represents the number of shares the employees use to repay the employer.

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No definition available.

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Number of shares (or other type of equity) issued during the period as a result of any equity-based compensation plan other than an employee stock ownership plan (ESOP), net of any shares forfeited. Shares issued could result from the issuance of restricted stock, the exercise of stock options, stock issued under employee stock purchase plans, and/or other employee benefit plans.

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Share-Based Compensation - Additional Information (Detail) $ in Thousands	1 Months Ended		9 Months Ended
	Jun. 30, 2018 USD ($) Employee shares	May 31, 2017 USD ($) Employee shares	Sep. 30, 2018 USD ($) Anniversaries shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Options granted			0
Grand Canyon University [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of former employees hired \| Employee	100	100
Share-based compensation expense for restricted stock awards \| $			$ 7,880
Recognized deferred compensation plan expense for former GCE employees \| $			$ 9,568
2017 Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares available for grant			1,910,000
Maximum [Member] \| 2017 Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares available for grant			3,000,000
Restricted Stock Grants [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares granted			163,000
Shares withheld for taxes			151,000
Common stock in lieu of taxes \| $			$ 15,153
Forfeiture of shares by transferred employees at closing of transaction			94,000
Restricted Stock Grants [Member] \| Grand Canyon University [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares issued under plan	82,000	82,000
Share-based compensation expense for restricted stock awards \| $	$ 7,880	$ 7,880
Recognized deferred compensation plan expense for former GCE employees \| $	$ 9,568
Forfeiture of shares by transferred employees at closing of transaction	86,000
Restricted Stock Grants [Member] \| 2008 Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares granted			160,000
Vesting period			5 years
Number of anniversaries of the vesting date following the date of grant \| Anniversaries			4
Restricted Stock Grants [Member] \| 2017 Plan [Member] \| Non-employee [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares granted			3,000
Restricted Stock Grants [Member] \| Share-based Compensation Award, Tranche One [Member] \| 2008 Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting right percentage			20.00%
Restricted Stock Grants [Member] \| Share-based Compensation Award, Tranche Two [Member] \| 2008 Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting right percentage			20.00%
Restricted Stock Grants [Member] \| Share-based Compensation Award, Tranche Three [Member] \| 2008 Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting right percentage			20.00%
Restricted Stock Grants [Member] \| Share-based Compensation Award Tranche Four [Member] \| 2008 Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting right percentage			20.00%
Restricted Stock Grants [Member] \| Share-based Compensation Award Tranche Five [Member] \| 2008 Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting right percentage			20.00%
Employee Stock Option [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Options granted			0