Goodwill and Other Intangible Assets - Schedule of Reconciliation of Changes in Carrying Value of Goodwill (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Goodwill And Intangible Assets [Line Items]
Balance, Beginning of year	$ 87,356	$ 87,356
Business acquisition	30,956
Balance, End of year	118,312	87,356
CTU [Member]
Goodwill And Intangible Assets [Line Items]
Balance, Beginning of year	45,938	45,938
Business acquisition
Balance, End of year	45,938	45,938
AIU [Member]
Goodwill And Intangible Assets [Line Items]
Balance, Beginning of year	41,418	41,418
Business acquisition	30,956
Balance, End of year	$ 72,374	$ 41,418