Student Receivables - Changes in Current and Non-Current Receivables Allowance (Detail) - USD ($) $ in Thousands		3 Months Ended		9 Months Ended
		Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Receivables [Abstract]
Balance, Beginning of Period		$ 24,268	$ 24,574	$ 22,534	$ 23,142
Charges to Expense	[1]	7,932	6,420	21,675	21,630
Amounts Written-off		(8,649)	(6,332)	(20,658)	(20,110)
Balance, End of Period		$ 23,551	$ 24,662	$ 23,551	$ 24,662

[1] Charges to expense include an offset for recoveries of amounts previously written off of $1.8 million and $0.8 million for the quarters ended September 30, 2018 and 2017, and $4.3 million and $3.5 million for the years to date ended September 30, 2018 and 2017, respectively.