Goodwill and Intangible Assets - Narrative (Details) - USD ($)	3 Months Ended				9 Months Ended		12 Months Ended
	Sep. 30, 2023	Jun. 30, 2023	Sep. 30, 2022	Jun. 30, 2022	Sep. 30, 2023	Sep. 30, 2022	Dec. 31, 2022	Jan. 01, 2022	Dec. 31, 2021	Sep. 01, 2021	Aug. 10, 2021
Purchase Price Allocation
Goodwill	$ 59,593,000				$ 59,593,000		$ 112,593,000		$ 243,486,000
Amortization	3,000,000		$ 4,000,000		10,900,000	$ 11,900,000
Impairment charge					53,000,000		131,400,000
Impairment					26,500,000		15,500,000
Indefinite-lived intangible assets	28,221,000				28,221,000		39,221,000
Impairment of goodwill and intangible assets	0		$ 0		64,000,000	$ 144,900,000
Accreditation and licenses
Purchase Price Allocation
Impairment					18,500,000		15,500,000
Indefinite-lived intangible assets	7,686,000				7,686,000		$ 10,686,000
RU Segment
Purchase Price Allocation
Goodwill	33,000,000				33,000,000					$ 217,400,000
Indefinite-lived intangible assets acquired	24,500,000				24,500,000					$ 51,000,000
Amount	35,500,000				35,500,000
Impairment charge		$ 53,000,000		$ 131,400,000
Goodwill, impairment loss, tax effect		15,800,000		36,000,000
Impairment of goodwill and intangible assets		64,000,000		144,900,000
RU Segment | Trade name
Purchase Price Allocation
Indefinite-lived intangible assets		18,500,000
RU Segment | Accreditation and licenses
Purchase Price Allocation
Impairment		11,000,000		$ 13,500,000
Indefinite-lived intangible assets		$ 6,000,000
HCN Segment
Purchase Price Allocation
Goodwill	26,600,000				26,600,000				38,600,000
Indefinite-lived intangible assets acquired									$ 3,700,000
Amount	4,400,000				4,400,000
GSUSA Segment
Purchase Price Allocation
Goodwill								$ 0			$ 0
Indefinite-lived intangible assets acquired	0				0
Amount	1,000,000				1,000,000
APUS Segment
Purchase Price Allocation
Indefinite-lived intangible assets acquired	0				0
Amount	$ 0				$ 0