Consolidated Statements of Cash Flows - USD ($)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Operating activities
Net income	$ 21,121,000	$ 24,155,000	$ 32,414,000
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	18,776,000	19,384,000	20,520,000
Stock-based compensation	6,246,000	5,211,000	5,912,000
Equity investment loss/(income)	2,430,000	(703,000)	(90,000)
Deferred income taxes	(2,494,000)	(455,000)	(160,000)
Loss on disposal of long-lived assets	2,093,000	5,970,000	817,000
Impairment of goodwill	0	4,735,000	0
Other	353,000	329,000	(133,000)
Changes in operating assets and liabilities:
Accounts receivable, net of allowance for bad debt	(187,000)	968,000	(1,787,000)
Prepaid expenses and other assets	(82,000)	997,000	64,000
Income tax receivable	0	0	2,029,000
Accounts payable	1,991,000	589,000	(4,765,000)
Accrued liabilities	(2,195,000)	(424,000)	56,000
Income tax payable	1,151,000	(123,000)	682,000
Deferred revenue and student deposits	(1,265,000)	(4,619,000)	1,453,000
Net cash provided by operating activities	47,938,000	56,014,000	57,012,000
Investing activities
Capital expenditures	(10,855,000)	(13,826,000)	(26,002,000)
Capitalized program development costs and other assets	(3,933,000)	(2,573,000)	(1,265,000)
Proceeds from the sale of real property	1,493,000	844,000	0
Equity investments	(300,000)	(950,000)	(3,871,000)
Dividend received from equity investment	0	2,957,000	0
Net cash used in investing activities	(13,595,000)	(13,548,000)	(31,138,000)
Financing activities
Cash paid for repurchase of common/restricted stock	(1,587,000)	(847,000)	(35,310,000)
Cash received from issuance of common stock	98,000	118,000	55,000
Excess tax expense from stock-based compensation	0	(1,120,000)	(519,000)
Net cash used in financing activities	(1,489,000)	(1,849,000)	(35,774,000)
Net increase (decrease) in cash and cash equivalents	32,854,000	40,617,000	(9,900,000)
Cash and cash equivalents at beginning of period	146,351,000	105,734,000	115,634,000
Cash and cash equivalents at end of period	179,205,000	146,351,000	105,734,000
Supplemental disclosures of cash flow information
Income taxes paid	$ 12,836,000	$ 16,637,000	$ 18,037,000