Revenue Recognition - Additional Information (Details) $ in Millions	3 Months Ended
	Mar. 31, 2019 USD ($) term Course item
Disaggregation of Revenue [Line Items]
Number of free courses | Course	1
Number of successfully completed courses | item	3
Consecutive terms of non attendance in which Graduation Fund credits will be lost | term	1
Expected collection period of current tuition receivable (in months)	12 months
Graduation fund estimated to be redeemed	$ 22.4
Unbilled receivables	$ 1.2
Minimum
Disaggregation of Revenue [Line Items]
Expected collection period of noncurrent tuition receivable (in years)	2 years
Maximum
Disaggregation of Revenue [Line Items]
Expected collection period of noncurrent tuition receivable (in years)	4 years