Summary of Significant Accounting Policies - Additional Information (Detail) - USD ($)	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016	Mar. 31, 2007	Jan. 01, 2017	Dec. 31, 2016
Summary Of Significant Accounting Policies [Line Items]
Average days from the date of receipt in which funds remain as restricted cash and cash equivalents	60 to 90 days
Period of LIBOR interest rate	30 days
Effective portion of loss on derivatives included as a component of other comprehensive income, net of taxes	$ 393,000	$ 39,000
Description of area of the company's campus in Phoenix, Arizona	260 acre campus
Reduction in revenue due to scholarships offered to students	$ 54,653,000	53,591,000
Period for write off of inactive student accounts			150 days
Excess tax benefits from financing activities		3,495,000
Reduction in provision for income taxes	8,524,000
Interest Rate Corridor [Member]
Summary Of Significant Accounting Policies [Line Items]
Notional amount of derivative instrument	$ 71,667,000
Description of interest rate risk hedge at several thresholds	The University pays variable interest monthly based on the 30 Day LIBOR rates until that index reaches 1.5%. If 30 Day LIBOR is equal to 1.5% through 3.0%, the University pays 1.5%. If 30 Day LIBOR exceeds 3.0%, the University pays actual 30 Day LIBOR less 1.5%.
Interest Rate Corridor [Member] | LIBOR [Member]
Summary Of Significant Accounting Policies [Line Items]
Maximum percentage of variable interest rates based on LIBOR	1.50%
Percentage of amount paid by University	1.50%
Percentage deducted from LIBOR for actual payment	1.50%
Cash Flow Hedging [Member]
Summary Of Significant Accounting Policies [Line Items]
Effective portion of loss on derivatives included as a component of other comprehensive income, net of taxes	$ 8,000	$ 386,000
Retained Earnings [Member]
Summary Of Significant Accounting Policies [Line Items]
Cumulative effect from the adoption of accounting pronouncements, net of taxes	(59,000)			$ (59,000)
Additional Paid-in Capital [Member]
Summary Of Significant Accounting Policies [Line Items]
Cumulative effect from the adoption of accounting pronouncements, net of taxes	59,000			$ 59,000
Other Assets [Member]
Summary Of Significant Accounting Policies [Line Items]
Fair values of interest rate corridor instrument	$ 483,000				$ 490,000
Minimum [Member]
Summary Of Significant Accounting Policies [Line Items]
Number of days from the date of receipt in which funds remain as restricted cash and cash equivalents	60 days
Minimum [Member] | Interest Rate Corridor [Member] | LIBOR [Member]
Summary Of Significant Accounting Policies [Line Items]
Percentage of LIBOR	1.50%
Maximum [Member]
Summary Of Significant Accounting Policies [Line Items]
Number of days from the date of receipt in which funds remain as restricted cash and cash equivalents	90 days
Maximum [Member] | Interest Rate Corridor [Member] | LIBOR [Member]
Summary Of Significant Accounting Policies [Line Items]
Percentage of LIBOR	3.00%