Acquisitions and Dispositions of Businesses (Assets Acquired and Liabilities Assumed) (Details 1) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2016	Dec. 31, 2015
Business Acquisition [Line Items]
Goodwill	$ 1,150,446	$ 1,017,513
2016 Acquisitions [Member]
Business Acquisition [Line Items]
Cash and cash equivalents	10,587
Accounts receivable	8,415
Inventory	971
Other current assets	1,420
Property, plant and equipment	3,940
Goodwill	181,228
Amortized intangible assets	27,267
Current liabilities	(20,714)
Noncurrent liabilities	(11,378)
Total	$ 254,846
Weighted Average Life (in years)	6 years
Trade Names and Trademarks [Member] | 2016 Acquisitions [Member]
Business Acquisition [Line Items]
Indefinite-lived intangible assets	$ 53,110
Student and Customer Relationships [Member] | 2016 Acquisitions [Member]
Business Acquisition [Line Items]
Amortized intangible assets	$ 22,292
Weighted Average Life (in years)	6 years
Trade Names and Trademarks [Member] | 2016 Acquisitions [Member]
Business Acquisition [Line Items]
Amortized intangible assets	$ 2,425
Weighted Average Life (in years)	6 years
Non-compete Agreements [Member] | 2016 Acquisitions [Member]
Business Acquisition [Line Items]
Amortized intangible assets	$ 350
Weighted Average Life (in years)	2 years
Other Intangible Assets [Member] | 2016 Acquisitions [Member]
Business Acquisition [Line Items]
Amortized intangible assets	$ 2,200
Weighted Average Life (in years)	7 years