Goodwill and Other Intangible Assets Goodwill and Other Intangible Assets (Goodwill) (Narrative) (Details) $ in Thousands |
3 Months Ended | 12 Months Ended | ||||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
Mar. 31, 2018
Segment
|
Dec. 31, 2017
USD ($)
|
Sep. 30, 2017
USD ($)
|
Jun. 30, 2017
USD ($)
|
Mar. 31, 2017
USD ($)
|
Dec. 31, 2016
USD ($)
business
|
Sep. 30, 2016
USD ($)
|
Jun. 30, 2016
USD ($)
|
Mar. 31, 2016
USD ($)
|
Dec. 31, 2015
USD ($)
|
Sep. 30, 2015
USD ($)
|
Dec. 31, 2017
USD ($)
Segment
|
Dec. 31, 2016
USD ($)
|
Dec. 31, 2015
USD ($)
|
|
Goodwill [Line Items] | ||||||||||||||
Number of reportable segments | Segment | 6 | |||||||||||||
Asset Impairment Charges | $ 78 | $ 312 | $ 9,224 | $ 0 | $ 9,614 | $ 1,603 | $ 259,700 | |||||||
Goodwill, Impairment Loss | $ 1,603 | $ 0 | $ 0 | $ 0 | 7,616 | 1,603 | ||||||||
Other Businesses [Member] | ||||||||||||||
Goodwill [Line Items] | ||||||||||||||
Number of businesses recorded impairment of goodwill | business | 1 | |||||||||||||
Goodwill, Impairment Loss | $ 1,600 | $ 2,800 | 7,616 | 1,603 | ||||||||||
Education [Member] | ||||||||||||||
Goodwill [Line Items] | ||||||||||||||
Goodwill, Impairment Loss | $ 0 | $ 0 | ||||||||||||
Forney [Member] | Other Businesses [Member] | ||||||||||||||
Goodwill [Line Items] | ||||||||||||||
Goodwill and Intangible Asset Impairment | $ 8,600 | |||||||||||||
Higher Education [Member] | Education [Member] | ||||||||||||||
Goodwill [Line Items] | ||||||||||||||
Goodwill, Impairment Loss | $ 248,600 | |||||||||||||
Subsequent Event [Member] | ||||||||||||||
Goodwill [Line Items] | ||||||||||||||
Number of reportable segments | Segment | 6 |