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

No definition available.

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Namespace Prefix:	lope_
Data Type:	xbrli:positiveIntegerItemType
Balance Type:	na
Period Type:	duration

- Definition

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.

+ References

No definition available.

+ Details

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Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

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.

+ 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
-Subparagraph (a)(1)
-URI http://asc.fasb.org/extlink&oid=109197908&loc=d3e5070-113901

+ Details

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Balance Type:	na
Period Type:	duration

- 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).

+ 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
-Subparagraph (c)(2)(iii)(1)
-URI http://asc.fasb.org/extlink&oid=109197908&loc=d3e5070-113901

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	duration

- 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.

+ Details

Name:	us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems
Namespace Prefix:	us-gaap_
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Balance Type:	na
Period Type:	duration

- Definition

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.

+ 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=109197908&loc=d3e5070-113901

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	instant

- Definition

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

+ 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
-Subparagraph (c)(1)(iv)(1)
-URI http://asc.fasb.org/extlink&oid=109197908&loc=d3e5070-113901

+ Details

Name:	us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriod
Namespace Prefix:	us-gaap_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	duration

- Definition

Percentage of vesting of share-based compensation awards.

+ References

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- 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.

+ References

No definition available.

+ Details

Name:	us-gaap_SharesPaidForTaxWithholdingForShareBasedCompensation
Namespace Prefix:	us-gaap_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	duration

- Details

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Namespace Prefix:
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- Details

Name:	srt_RangeAxis=srt_MaximumMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_AwardTypeAxis=us-gaap_RestrictedStockMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_PlanNameAxis=lope_TwoThousandEightEquityIncentivePlanMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

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Namespace Prefix:
Data Type:	na
Balance Type:
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- Details

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- Details

Name:	us-gaap_VestingAxis=us-gaap_ShareBasedCompensationAwardTrancheOneMember
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- Details

Name:	us-gaap_VestingAxis=us-gaap_ShareBasedCompensationAwardTrancheTwoMember
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- Details

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- Details

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- Details

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- Details

Name:	us-gaap_AwardTypeAxis=us-gaap_EmployeeStockOptionMember
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Share-Based Compensation - Additional Information (Detail) $ in Thousands	3 Months Ended	6 Months Ended
	Jun. 30, 2018 shares	Jun. 30, 2018 USD ($) Anniversaries shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Options granted		0
2017 Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares available for grant	1,861,000	1,861,000
Maximum [Member] \| 2017 Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares available for grant	3,000,000	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		119,000
Common stock in lieu of taxes \| $		$ 11,524
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
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