Consolidated Statements of Cash Flows (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Cash flows provided by operating activities:
Net income	$ 88,711	$ 69,447	$ 50,546
Adjustments to reconcile net income to net cash provided by operating activities:
Share-based compensation	9,936	7,811	6,452
Excess tax benefits from share-based compensation	(4,469)	(1,427)
Amortization of notes payable issuance costs		244	80
Provision for bad debts	19,897	18,012	34,364
Depreciation and amortization	25,437	21,923	17,034
Gain on note receivable	(3,646)
Loss on asset disposal		1,106
Exit costs			(64)
Lease termination fees			782
Deferred income taxes	5,472	(518)	20,794
Other			92
Changes in assets and liabilities:
Restricted cash and cash equivalents	(8,404)	151	(9,137)
Accounts receivable	(19,163)	(14,148)	(28,196)
Prepaid expenses and other	(7,316)	(1,920)	(6,158)
Due to/from related parties	(69)	296	(9,244)
Accounts payable	8,563	(630)	3,155
Accrued liabilities	(1,756)	15,719	(3,300)
Accrued litigation loss			(5,200)
Income taxes receivable/payable	(7,769)	20,593	(3,599)
Deferred rent	(204)	503	4,143
Deferred revenue	4,202	6,891	6,689
Student deposits	9,027	143	8,729
Net cash provided by operating activities	118,449	144,196	87,962
Cash flows used in investing activities:
Capital expenditures	(78,948)	(97,653)	(80,545)
Purchase of land and building related to off-site development	(14,542)	(7,223)
Investment in note receivable secured by real estate		(27,000)
Proceeds received from note receivable	29,187
Restricted funds held for derivative collateral and legal matter	225	330	5,405
Purchases of investments	(168,953)
Proceeds from sale or maturity of investments	60,533
Net cash used in investing activities	(172,498)	(131,546)	(75,140)
Cash flows provided by (used in) financing activities:
Principal payments on notes payable and capital lease obligations	(6,689)	(21,744)	(3,748)
Proceeds from notes payable		99,210
Notes payable modification costs		(428)	(91)
Repurchase of common shares including share withheld in lieu of income taxes	(9,296)	(15,242)	(23,112)
Net proceeds from exercise of stock options	16,278	8,049	1,681
Excess tax benefits from share-based compensation	4,469	1,427
Net cash provided by (used in) financing activities	4,762	71,272	(25,270)
Net (decrease) increase in cash and cash equivalents	(49,287)	83,922	(12,448)
Cash and cash equivalents, beginning of year	105,111	21,189	33,637
Cash and cash equivalents, end of year	55,824	105,111	21,189
Supplemental disclosure of cash flow information
Cash paid during the year for interest	2,176	606	535
Cash paid during the year for income taxes	59,892	32,810	13,463
Cash received for income tax refunds	728	7,938	5
Supplemental disclosure of non-cash investing and financing activities
Purchase of equipment through notes payable and capital lease obligations			801
Purchases of property and equipment included in accounts payable and deferred rent	1,494	3,291	325
Shortfall tax expense from share-based compensation	209	283	151
Tax benefit of Spirit warrant intangible	$ 267	$ 267	$ 291