Merger with Capella Education Company - Revenue and Net Loss (Details) - USD ($) $ in Thousands	2 Months Ended	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Business Acquisition [Line Items]
Revenues		$ 160,945	$ 108,512	$ 392,082	$ 336,144
Net loss		$ (52,781)	$ 6,227	$ (38,126)	$ 27,107
Capella Education Company
Business Acquisition [Line Items]
Revenues	$ 46,100
Net loss	$ 43,100