Revenue Recognition - Changes in Deferred Revenue Balances (Detail) - USD ($) $ in Thousands		3 Months Ended		9 Months Ended
		Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Deferred Revenue Arrangement [Line Items]
Business acquisition, beginning balance		$ 5,356		$ 5,356	$ 13,395
Gross deferred revenue, beginning balance		121,467	$ 67,817	85,402	63,204
Revenue earned from prior balances		(99,501)	(56,271)	(72,203)	(63,280)
Billings during period	[1]	137,209	156,817	531,319	492,316
Revenue earned for new billings during the period		(73,094)	(112,200)	(458,027)	(451,084)
Other adjustments		650	(1,107)	240	505
Gross deferred revenue, ending balance		92,087	55,056	92,087	55,056
University Group [Member] | CTU [Member]
Deferred Revenue Arrangement [Line Items]
Business acquisition, beginning balance		3,952		3,952
Gross deferred revenue, beginning balance		77,818	28,092	28,522	27,845
Revenue earned from prior balances		(66,878)	(25,035)	(26,183)	(24,376)
Billings during period	[1]	90,662	99,219	348,307	301,727
Revenue earned for new billings during the period		(37,469)	(73,411)	(285,186)	(276,802)
Other adjustments		951	(777)	(376)	(306)
Gross deferred revenue, ending balance		69,036	28,088	69,036	28,088
University Group [Member] | AIU [Member]
Deferred Revenue Arrangement [Line Items]
Business acquisition, beginning balance		1,404		1,404	13,395
Gross deferred revenue, beginning balance		43,649	39,725	56,880	35,359
Revenue earned from prior balances		(32,623)	(31,236)	(46,020)	(38,904)
Billings during period	[1]	46,547	57,598	183,012	190,589
Revenue earned for new billings during the period		(35,625)	(38,789)	(172,841)	(174,282)
Other adjustments		(301)	(330)	616	811
Gross deferred revenue, ending balance		$ 23,051	$ 26,968	$ 23,051	$ 26,968

[1] Billings during period includes adjustments for prior billings.