Property and Equipment - Additional Information (Detail) (USD $) In Thousands, unless otherwise specified	12 Months Ended
Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Property, Plant and Equipment [Abstract]
Depreciation and amortization expense including assets under capital lease	$ 28,529	$ 24,546	$ 21,264

Depreciation and amortization including assets under capital lease.

No definition available.

Name:	lope_DepreciationAndAmortizationIncludingAssetsUnderCapitalLease
Namespace Prefix:	lope_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration