XML 40 R29.htm IDEA: XBRL DOCUMENT v3.8.0.1

Investments - Additional Information (Detail) $ in Thousands	9 Months Ended
	Sep. 30, 2017 USD ($)
Schedule of Available-for-sale Securities [Line Items]
Unrealized net (losses) gains on available-for-sale securities	$ 14
Municipal Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Maturity period of investments	One year or less

X

- Definition

Investment maturity period.

+ References

No definition available.

+ Details

Name:	lope_InvestmentMaturityPeriod
Namespace Prefix:	lope_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

X

- Definition

The change in unrealized holding gain (loss), net of tax, on available-for-sale securities included in a separate component of shareholders' equity during the period.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 50
-Paragraph 9
-Subparagraph (d)
-URI http://asc.fasb.org/extlink&oid=82897076&loc=d3e27357-111563

+ Details

Name:	us-gaap_AvailableForSaleSecuritiesChangeInNetUnrealizedHoldingGainLossNetOfTax
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

X

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

X

- Details

Name:	us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis=us-gaap_DebtSecuritiesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: