Business Combinations - Acquisition Related Costs and Measurement period adjustments (Details) - USD ($) $ in Thousands		12 Months Ended
	Aug. 01, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2020
Business Acquisition [Line Items]
Goodwill		$ 732,075	$ 732,540	$ 1,318,526
Issuance costs			148
Strayer University
Business Acquisition [Line Items]
Goodwill		337,381	337,381	337,381
Capella University
Business Acquisition [Line Items]
Goodwill		394,694	$ 395,159	$ 394,694
Capella Merger
Business Acquisition [Line Items]
Conversion ratio (in shares)	0.875
Goodwill	$ 725,275
Transaction costs	20,100
Issuance costs	100
Measurement period adjustment, (reduction) of deferred income taxes		(3,800)
Measurement period adjustment, (reduction) of current assets		(1,900)
Measurement period adjustment, increase of current liabilities		1,300
Measurement period adjustment, increase of long term liabilities		100
Increase (decrease) of goodwill		$ (500)
Capella Merger | Strayer University
Business Acquisition [Line Items]
Goodwill	330,600
Capella Merger | Capella University
Business Acquisition [Line Items]
Goodwill	$ 394,700