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Share-Based Compensation Plans - Summary of Activity Related to Stock Options Granted Under Company's Incentive Plan (Parenthetical) (Detail) (USD $) | Dec. 31, 2012
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Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |
Value of closing stock price | $ (23.47)

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- Definition Value of closing stock price. + References No definition available. + Details
Name: | lope_ValueOfClosingStockPrice
Namespace Prefix: | lope_
Data Type: | num:perShareItemType
Balance Type: | na
Period Type: | instant

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- Details
Name: | us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration