Restatement of Consolidated Financial Statements (Details) (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2011	Jun. 30, 2010	Jun. 30, 2011	Jun. 30, 2010	Dec. 31, 2010
Results of operations
Net revenue	$ 103,118	$ 97,322	$ 204,827	$ 186,648
Costs and expenses:
Instructional costs and services	46,354	51,032	95,229	87,692
Selling and promotional	27,709	28,976	57,541	55,852
General and administrative	7,038	6,176	13,870	12,280
Exit costs		116		205
Total costs and expenses	81,101	86,300	166,640	156,029
Operating income	22,017	11,022	38,187	30,619
Interest expense	(29)	(162)	(136)	(506)
Income before income taxes	22,014	10,897	38,109	30,211
Income tax expense	9,141	4,163	15,755	11,997
Net income	12,873	6,734	22,354	18,214
Earnings per share:
Basic income per share	$ 0.29	$ 0.15	$ 0.50	$ 0.40
Diluted income per share	$ 0.29	$ 0.14	$ 0.49	$ 0.39
Basic	44,658	45,724	45,122	45,699
Diluted	45,018	46,557	45,551	46,441
Results of financial position
Accounts receivable, net of allowance for doubtful accounts of and $37,145 (As Restated)	13,078		13,078		17,983
Allowance for doubtful accounts	36,945		36,945		30,112
Deferred income taxes - current	13,911		13,911		16,078
Total current assets	98,446		98,446		133,125
Total assets	278,582		278,582		275,096
Accumulated earnings	73,175		73,175		50,821
Total stockholders' equity	131,298		131,298		127,501
Total liabilities and stockholders' equity	278,582		278,582		275,096
Results of cash flows
Net income	12,873	6,734	22,354	18,214
Provision for bad debts			18,277	19,563
Deferred income taxes			1,392	(9,802)
Accounts receivable			(13,372)	(42,920)
Net cash provided by operating activities			36,026	30,127
Restatement of Condensed Consolidated Financial Statements (Textual) [Abstract]
Percentage of financial aid			100.00%
Allowance for doubtful accounts	36,945		36,945		30,112
Scenario, Previously Reported [Member]
Results of operations
Net revenue	103,118	97,522	204,827	186,848
Costs and expenses:
Instructional costs and services	45,709	41,742	91,539	78,402
Selling and promotional	27,709	28,976	57,541	55,852
General and administrative	7,038	6,176	13,870	12,280
Exit costs		116		205
Total costs and expenses	80,456	77,010	162,950	146,739
Operating income	22,662	20,512	41,877	40,109
Interest expense	(3)	(125)	(78)	(408)
Income before income taxes	22,659	20,387	41,799	39,701
Income tax expense	9,401	7,991	17,243	15,825
Net income	13,258	12,396	24,556	23,876
Earnings per share:
Basic income per share	$ 0.30	$ 0.27	$ 0.54	$ 0.52
Diluted income per share	$ 0.29	$ 0.27	$ 0.54	$ 0.51
Basic	44,658	45,724	45,122	45,699
Diluted	45,018	46,557	45,551	46,441
Results of financial position
Accounts receivable, net of allowance for doubtful accounts of and $37,145 (As Restated)	32,120	42,636	32,120	42,636
Allowance for doubtful accounts	18,103	11,182	18,103	11,182
Deferred income taxes - current	6,230	11,355	6,230	11,355
Total current assets	109,807	132,933	109,807	132,933
Total assets	289,943	237,813	289,943	237,813
Accumulated earnings	84,536	39,491	84,536	39,491
Total stockholders' equity	142,659	113,307	142,659	113,307
Total liabilities and stockholders' equity	289,943	237,813	289,943	237,813
Results of cash flows
Net income	13,258	12,396	24,556	23,876
Provision for bad debts			14,586	10,273
Deferred income taxes			2,881	(5,974)
Accounts receivable			(13,372)	(43,120)
Net cash provided by operating activities			36,026	30,127
Restatement of Condensed Consolidated Financial Statements (Textual) [Abstract]
Allowance for doubtful accounts	18,103	11,182	18,103	11,182
Scenario Previously Restated [Member]
Results of operations
Net revenue	103,118	97,322	204,827	186,648
Costs and expenses:
Instructional costs and services	46,354	51,032	95,229	87,692
Selling and promotional	27,709	28,976	57,541	55,852
General and administrative	7,038	6,176	13,870	12,280
Exit costs		116		205
Total costs and expenses	81,101	86,300	166,640	156,029
Operating income	22,017	11,022	38,187	30,619
Interest expense	(3)	(125)	(78)	(408)
Income before income taxes	22,014	10,897	38,109	30,211
Income tax expense	9,141	4,163	15,755	11,997
Net income	12,873	6,734	22,354	18,214
Earnings per share:
Basic income per share	$ 0.29	$ 0.15	$ 0.50	$ 0.40
Diluted income per share	$ 0.29	$ 0.14	$ 0.49	$ 0.39
Basic	44,658	45,724	45,122	45,699
Diluted	45,018	46,557	45,551	46,441
Results of financial position
Accounts receivable, net of allowance for doubtful accounts of and $37,145 (As Restated)	13,078	33,146	13,078	33,146
Allowance for doubtful accounts	36,945	20,472	36,945	20,472
Deferred income taxes - current	13,911	15,183	13,911	15,183
Total current assets	98,446	127,271	98,446	127,271
Total assets	278,582	232,151	278,582	232,151
Accumulated earnings	73,175	33,829	73,175	33,829
Total stockholders' equity	131,298	107,645	131,298	107,645
Total liabilities and stockholders' equity	278,582	232,151	278,582	232,151
Results of cash flows
Net income	12,873	6,734	22,354	18,214
Provision for bad debts			18,277	19,563
Deferred income taxes			1,392	(9,802)
Accounts receivable			(13,372)	(42,920)
Net cash provided by operating activities			36,026	30,127
Restatement of Condensed Consolidated Financial Statements (Textual) [Abstract]
Allowance for doubtful accounts	$ 36,945	$ 20,472	$ 36,945	$ 20,472