Other Non-Operating Income (Narrative) (Details) $ in Thousands	3 Months Ended
	Mar. 31, 2018 USD ($) business	Mar. 31, 2017 USD ($)
Schedule of Non-Operating Income (Expense) [Line Items]
Document Fiscal Year Focus	2018
Gain on sale of business	$ 5,907	$ (342)
Education [Member]
Schedule of Non-Operating Income (Expense) [Line Items]
Gain on sale of business	$ 5,907
Number of businesses disposed | business	2
Higher Education [Member] | Education [Member] | Kaplan University Transaction [Member]
Schedule of Non-Operating Income (Expense) [Line Items]
Gain on sale of business	$ 4,300