Consolidated Statements of Income (Unaudited) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Income Statement [Abstract]
Revenue	$ 72,992	$ 73,279	$ 220,757	$ 221,163
Costs and expenses:
Instructional costs and services	28,186	28,723	86,839	87,513
Selling and promotional	14,139	14,640	43,004	44,083
General and administrative	19,298	17,237	55,780	51,625
Loss on disposals of long-lived assets	196	390	882	1,558
Depreciation and amortization	4,289	4,690	13,158	14,160
Total costs and expenses	66,108	65,680	199,663	198,939
Income from operations before interest income and income taxes	6,884	7,599	21,094	22,224
Interest income, net	774	17	1,928	43
Income before income taxes	7,658	7,616	23,022	22,267
Income tax expense	1,848	3,294	5,993	9,668
Equity investment (loss) income	(311)	44	(483)	105
Net income	$ 5,499	$ 4,366	$ 16,546	$ 12,704
Net Income per common share:
Basic (in dollars per share)	$ 0.33	$ 0.27	$ 1.01	$ 0.78
Diluted (in dollars per share)	$ 0.33	$ 0.27	$ 1.00	$ 0.78
Weighted average number of common shares:
Basic (in shares)	16,423,548	16,248,623	16,397,483	16,225,869
Diluted (in shares)	16,658,159	16,375,512	16,627,532	16,351,563