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Segment and Geographic Information - Concentration Risk (Details) $ in Thousands	3 Months Ended		12 Months Ended
	Mar. 31, 2020 USD ($) segment	Mar. 31, 2019 USD ($)	Dec. 31, 2019 USD ($)
Segment Information
Number of reportable segments (in segments) \| segment	2
Revenue	$ 175,479	$ 122,234
Accounts receivable, net	75,411		$ 33,655
Graduate Program Segment
Segment Information
Revenue	118,457	104,174
Alternative Credit Segment
Segment Information
Revenue	57,022	18,060
University client A \| Customer concentration risk \| Sales Revenue, Net \| Graduate Program Segment
Segment Information
Revenue	$ 17,500	$ 22,600
Percentage of concentration of credit risk	10.00%	18.00%
University client A \| Customer concentration risk \| Revenue segment \| Alternative Credit Segment
Segment Information
Revenue	$ 7,900
Percentage of concentration of credit risk	14.00%
University client A \| Credit concentration risk \| Accounts receivable, net \| Graduate Program Segment
Segment Information
Percentage of concentration of credit risk	11.00%		18.00%
Accounts receivable, net	$ 8,700		$ 6,100
University client B \| Customer concentration risk \| Sales Revenue, Net \| Graduate Program Segment
Segment Information
Revenue		$ 12,900
Percentage of concentration of credit risk		11.00%
University client B \| Credit concentration risk \| Accounts receivable, net \| Graduate Program Segment
Segment Information
Percentage of concentration of credit risk			15.00%
Accounts receivable, net			$ 4,900
University client C \| Customer concentration risk \| Sales Revenue, Net \| Graduate Program Segment
Segment Information
Revenue		$ 12,700
Percentage of concentration of credit risk		10.00%
Four university clients \| Customer concentration risk \| Revenue segment \| Alternative Credit Segment
Segment Information
Percentage of concentration of credit risk		88.00%