Other Employee Benefit Plans - Narrative (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Company's contributions to 401(K) plan	$ 8.2	$ 7.7	$ 7.4
Common stock shares purchase price limit for employees as percentage of market value under ESPP	90.00%
Employee stock purchase plan maximum percentage of purchase employee can make on eligible compensation	10.00%
Maximum number of shares available for purchase by participating employees (in shares)	2,500,000
Australia / New Zealand
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Long service leave expense	$ 8.6	$ 8.7	$ 8.4
Strategic Education, Inc. 401(k) Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Percentage of company matching contribution to 401(K) plan, first tier	100.00%
Defined contribution plan employer matching contribution percent, first tier	2.00%
Percentage of company matching contribution to 401(K) plan, second tier	50.00%
Defined contribution plan employer matching contribution percent, second tier	2.00%
Defined contribution plan maximum employer matching contribution percent	3.00%