Business Segments (Narrative) (Details) $ in Thousands		3 Months Ended								12 Months Ended
	Mar. 22, 2018 USD ($)	Dec. 31, 2023 USD ($) televisionStation restaurant automotiveDealership	Sep. 30, 2023 USD ($)	Jun. 30, 2023 USD ($)	Mar. 31, 2023 USD ($)	Dec. 31, 2022 USD ($)	Sep. 30, 2022 USD ($)	Jun. 30, 2022 USD ($)	Mar. 31, 2022 USD ($)	Dec. 31, 2023 USD ($) televisionStation restaurant segment automotiveDealership	Dec. 31, 2022 USD ($)	Dec. 31, 2021 USD ($)
Segment Reporting Information [Line Items]
Number of reportable segments | segment										7
Operating and Management Services Expenses										$ 4,345,484	$ 3,840,595	$ 3,108,599
Operating Revenues		$ 1,166,813	$ 1,111,519	$ 1,104,999	$ 1,031,546	$ 1,064,032	$ 1,012,438	$ 933,302	$ 914,721	$ 4,414,877	3,924,493	3,185,974
Clyde's Restaurant Group [Member]
Segment Reporting Information [Line Items]
Number of Restaurants | restaurant		12								12
Non U.S. [Member]
Segment Reporting Information [Line Items]
Operating Revenues										$ 930,000	776,000	709,000
Foreign assets		$ 492,000				$ 477,000				492,000	477,000
Education [Member] | UNITED KINGDOM
Segment Reporting Information [Line Items]
Operating Revenues										$ 543,000	448,000	404,000
Television Broadcasting [Member]
Segment Reporting Information [Line Items]
Number of television broadcast stations owned | televisionStation		7								7
Automotive [Member]
Segment Reporting Information [Line Items]
Number of dealerships | automotiveDealership		8								8
Automotive [Member] | Related Party [Member]
Segment Reporting Information [Line Items]
Operating and Management Services Expenses										$ 7,300	$ 5,700	$ 3,600
Kaplan University Transaction [Member] | Education [Member] | Higher Education [Member] | Purdue University Global [Member]
Segment Reporting Information [Line Items]
Accounts receivable		$ 98,200								98,200
Accounts receivable, noncurrent		$ 19,600								$ 19,600
Advance Related To Kaplan University Transaction	$ 20,000