Goodwill and Other Intangible Assets (Other Intangible Assets) (Details) 2 (USD $) In Thousands, unless otherwise specified	9 Months Ended	12 Months Ended
	Sep. 30, 2013	Dec. 31, 2012
Amortized intangible assets [Abstract]
Gross Carrying Amount	$ 131,439	$ 129,641
Accumulated Amortization	87,897	84,064
Net Carrying Amount	43,542	45,577
Indefinite Lived Intangible Assets Excluding Goodwill [Line Items]
Indefinite-Lived Intangible Assets, Net	541,478	539,728
Franchise Agreements [Member]
Indefinite Lived Intangible Assets Excluding Goodwill [Line Items]
Indefinite-Lived Intangible Assets, Net	496,321	496,321
Wireless Licenses [Member]
Indefinite Lived Intangible Assets Excluding Goodwill [Line Items]
Indefinite-Lived Intangible Assets, Net	22,150	22,150
Licensure and Accreditation [Member]
Indefinite Lived Intangible Assets Excluding Goodwill [Line Items]
Indefinite-Lived Intangible Assets, Net	7,371	7,371
Other [Member]
Indefinite Lived Intangible Assets Excluding Goodwill [Line Items]
Indefinite-Lived Intangible Assets, Net	15,636	13,886
Non-compete Agreements [Member]
Amortized intangible assets [Abstract]
Gross Carrying Amount	14,054	14,008
Accumulated Amortization	13,038	12,546
Net Carrying Amount	1,016	1,462
Non-compete Agreements [Member] | Minimum [Member]
Amortized intangible assets [Abstract]
Useful Life	2 years	2 years
Non-compete Agreements [Member] | Maximum [Member]
Amortized intangible assets [Abstract]
Useful Life	5 years	5 years
Student and Customer Relationships [Member]
Amortized intangible assets [Abstract]
Gross Carrying Amount	70,918	73,693
Accumulated Amortization	42,141	40,787
Net Carrying Amount	28,777	32,906
Student and Customer Relationships [Member] | Minimum [Member]
Amortized intangible assets [Abstract]
Useful Life	2 years	2 years
Student and Customer Relationships [Member] | Maximum [Member]
Amortized intangible assets [Abstract]
Useful Life	10 years	10 years
Databases and Technology [Member]
Amortized intangible assets [Abstract]
Gross Carrying Amount	10,539	6,457
Accumulated Amortization	6,457	5,707
Net Carrying Amount	4,082	750
Databases and Technology [Member] | Minimum [Member]
Amortized intangible assets [Abstract]
Useful Life	3 years	3 years
Databases and Technology [Member] | Maximum [Member]
Amortized intangible assets [Abstract]
Useful Life	5 years	5 years
Trade Names and Trademarks [Member]
Amortized intangible assets [Abstract]
Gross Carrying Amount	26,100	26,634
Accumulated Amortization	19,124	18,185
Net Carrying Amount	6,976	8,449
Trade Names and Trademarks [Member] | Minimum [Member]
Amortized intangible assets [Abstract]
Useful Life	2 years	2 years
Trade Names and Trademarks [Member] | Maximum [Member]
Amortized intangible assets [Abstract]
Useful Life	10 years	10 years
Other [Member]
Amortized intangible assets [Abstract]
Gross Carrying Amount	9,828	8,849
Accumulated Amortization	7,137	6,839
Net Carrying Amount	$ 2,691	$ 2,010
Other [Member] | Minimum [Member]
Amortized intangible assets [Abstract]
Useful Life	1 year	1 year
Other [Member] | Maximum [Member]
Amortized intangible assets [Abstract]
Useful Life	25 years	25 years