Consolidated Income Statements - USD ($) shares in Thousands, $ in Thousands	3 Months Ended	12 Months Ended
Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Income Statement [Abstract]
Net revenue	$ 271,418	$ 236,209	$ 218,301	$ 248,206	$ 244,663	$ 210,444	$ 191,279	$ 226,958	$ 974,134	$ 873,344	$ 778,200
Costs and expenses:
Instructional costs and services	108,933	104,303	95,030	102,574	102,100	91,748	84,599	94,654	410,840	373,101	329,651
Admissions advisory and related	34,061	31,426	31,085	31,972	32,062	28,814	28,866	29,544	128,544	119,286	112,572
Advertising	23,678	25,523	24,776	24,631	21,000	23,896	22,149	21,107	98,608	88,152	76,229
Marketing and promotional	2,555	2,350	2,264	2,460	2,383	2,127	2,108	2,242	9,629	8,860	7,287
General and administrative	10,845	12,915	10,058	9,941	10,260	13,430	8,809	10,720	43,759	43,219	42,100
Lease termination costs					160	3,363				3,523
Total costs and expenses	180,072	176,517	163,213	171,578	167,965	163,378	146,531	158,267	691,380	636,141	567,839
Operating income	91,346	59,692	55,088	76,628	76,698	47,066	44,748	68,691	282,754	237,203	210,361
Interest expense	(527)	(567)	(495)	(580)	(497)	(344)	(158)	(329)	(2,169)	(1,328)	(1,248)
Interest income and other	757	1,445	739	2	199	(2,291)	293	2,048	2,943	249	(106)
Income before income taxes	91,576	60,570	55,332	76,050	76,400	44,431	44,883	70,410	283,528	236,124	209,007
Income tax expense	23,320	21,266	15,485	20,138	28,421	15,187	17,257	26,745	80,209	87,610	77,596
Net income	$ 68,256	$ 39,304	$ 39,847	$ 55,912	$ 47,979	$ 29,244	$ 27,626	$ 43,665	$ 203,319	$ 148,514	$ 131,411
Earnings per share:
Basic income per share	$ 1.44	$ 0.83	$ 0.85	$ 1.20	$ 1.03	$ 0.63	$ 0.60	$ 0.96	$ 4.31	$ 3.22	$ 2.86
Diluted income per share	$ 1.41	$ 0.81	$ 0.83	$ 1.16	$ 1.01	$ 0.62	$ 0.59	$ 0.93	$ 4.22	$ 3.15	$ 2.78
Basic weighted average shares outstanding	47,342	47,316	47,151	46,748	46,470	46,231	46,004	45,622	47,140	46,083	45,975
Diluted weighted average shares outstanding	48,382	48,292	48,192	48,070	47,452	47,175	46,990	46,860	48,235	47,121	47,281

Admissions advisory and related expenses.

No definition available.

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

- Definition

Costs directly attributable to educational services, including salaries and benefits for full-time faculty, administrators and academic advisors, and costs associated with adjunct faculty. Also includes costs for educational supplies such as books, costs associated with academic records and graduation, costs associated with collections from our students such as bad debt expense, and other university services such as evaluating transcripts.

+ References

No definition available.