Business Segments (Information by Operating Segment) (Details 1) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023	Dec. 31, 2023
Segment Reporting Information [Line Items]
Operating Revenues	$ 1,152,662	$ 1,031,546
Income (Loss) from Operations before Amortization of Intangible Assets and Impairment of Long-Lived Assets	46,193	42,345
Amortization of Intangible Assets and Impairment of Long-Lived Assets	10,751	14,689
Income (Loss) from Operations	35,442	27,656
Equity in earnings of affiliates, net	2,331	4,661
Interest Expense, Net	(17,150)	(13,090)
Non-operating pension and postretirement benefit income, net	42,417	31,845
Gain on marketable equity securities, net	104,152	18,022
Other Income, Net	1,647	3,083
Income Before Income Taxes	168,839	72,177
Depreciation of property, plant and equipment	22,527	20,025
Pension Service Cost	14,034	9,243
Identifiable Assets	4,144,467		$ 4,197,459
Marketable equity securities	794,305		690,153
Investments in Affiliates	186,674		186,480
Prepaid Pension Cost	2,129,682		2,113,638
Total Assets	7,255,128		7,187,730
Amortization of Intangible Assets	10,751	13,944
Impairment of long-lived assets	0	745
Operating Segments [Member] | Education [Member]
Segment Reporting Information [Line Items]
Operating Revenues	422,598	378,041
Income (Loss) from Operations before Amortization of Intangible Assets and Impairment of Long-Lived Assets	33,561	27,456
Amortization of Intangible Assets and Impairment of Long-Lived Assets	2,974	4,416
Income (Loss) from Operations	30,587	23,040
Depreciation of property, plant and equipment	9,305	8,968
Pension Service Cost	4,110	2,198
Identifiable Assets	1,939,781		2,021,471
Amortization of Intangible Assets	2,974	3,939
Impairment of long-lived assets	0	477
Operating Segments [Member] | Education [Member] | Reportable Subsegments [Member] | Kaplan International [Member]
Segment Reporting Information [Line Items]
Operating Revenues	269,798	227,076
Income (Loss) from Operations before Amortization of Intangible Assets and Impairment of Long-Lived Assets	31,312	21,301
Income (Loss) from Operations	31,312	21,301
Depreciation of property, plant and equipment	7,356	6,330
Pension Service Cost	163	80
Identifiable Assets	1,453,727		1,537,989
Operating Segments [Member] | Education [Member] | Reportable Subsegments [Member] | Higher Education [Member]
Segment Reporting Information [Line Items]
Operating Revenues	80,122	78,341
Income (Loss) from Operations before Amortization of Intangible Assets and Impairment of Long-Lived Assets	5,519	7,083
Income (Loss) from Operations	5,519	7,083
Depreciation of property, plant and equipment	903	1,102
Pension Service Cost	1,781	922
Identifiable Assets	200,115		187,972
Operating Segments [Member] | Education [Member] | Reportable Subsegments [Member] | Supplemental Education [Member]
Segment Reporting Information [Line Items]
Operating Revenues	72,122	73,587
Income (Loss) from Operations before Amortization of Intangible Assets and Impairment of Long-Lived Assets	4,580	3,751
Income (Loss) from Operations	4,580	3,751
Depreciation of property, plant and equipment	1,019	1,509
Pension Service Cost	1,818	1,024
Identifiable Assets	237,263		249,519
Operating Segments [Member] | Education [Member] | Kaplan Corporate and Other [Member]
Segment Reporting Information [Line Items]
Operating Revenues	2,588	2,372
Income (Loss) from Operations before Amortization of Intangible Assets and Impairment of Long-Lived Assets	(7,585)	(4,838)
Income (Loss) from Operations	(10,559)	(9,254)
Depreciation of property, plant and equipment	27	27
Pension Service Cost	348	172
Identifiable Assets	48,676		45,991
Operating Segments [Member] | Education [Member] | Intersubsegment Eliminations [Member]
Segment Reporting Information [Line Items]
Operating Revenues	(2,032)	(3,335)
Income (Loss) from Operations before Amortization of Intangible Assets and Impairment of Long-Lived Assets	(265)	159
Income (Loss) from Operations	(265)	159
Operating Segments [Member] | Television Broadcasting [Member]
Segment Reporting Information [Line Items]
Operating Revenues	113,058	112,877
Income (Loss) from Operations before Amortization of Intangible Assets and Impairment of Long-Lived Assets	30,983	29,945
Amortization of Intangible Assets and Impairment of Long-Lived Assets	1,350	1,362
Income (Loss) from Operations	29,633	28,583
Depreciation of property, plant and equipment	2,868	3,036
Pension Service Cost	1,639	860
Identifiable Assets	419,819		419,557
Operating Segments [Member] | Manufacturing [Member]
Segment Reporting Information [Line Items]
Operating Revenues	101,903	114,584
Income (Loss) from Operations before Amortization of Intangible Assets and Impairment of Long-Lived Assets	6,189	12,190
Amortization of Intangible Assets and Impairment of Long-Lived Assets	3,120	4,862
Income (Loss) from Operations	3,069	7,328
Depreciation of property, plant and equipment	2,715	2,282
Pension Service Cost	627	275
Identifiable Assets	436,797		431,712
Operating Segments [Member] | Healthcare [Member]
Segment Reporting Information [Line Items]
Operating Revenues	128,201	102,059
Income (Loss) from Operations before Amortization of Intangible Assets and Impairment of Long-Lived Assets	6,727	3,890
Amortization of Intangible Assets and Impairment of Long-Lived Assets	636	954
Income (Loss) from Operations	6,091	2,936
Depreciation of property, plant and equipment	1,594	1,104
Pension Service Cost	4,758	4,357
Identifiable Assets	267,707		265,150
Operating Segments [Member] | Automotive [Member]
Segment Reporting Information [Line Items]
Operating Revenues	303,840	232,561
Income (Loss) from Operations before Amortization of Intangible Assets and Impairment of Long-Lived Assets	9,652	10,843
Amortization of Intangible Assets and Impairment of Long-Lived Assets	0	0
Income (Loss) from Operations	9,652	10,843
Depreciation of property, plant and equipment	1,713	1,113
Pension Service Cost	15	5
Identifiable Assets	623,376		597,267
Operating Segments [Member] | Other Businesses [Member]
Segment Reporting Information [Line Items]
Operating Revenues	83,298	92,008
Income (Loss) from Operations before Amortization of Intangible Assets and Impairment of Long-Lived Assets	(26,283)	(27,906)
Amortization of Intangible Assets and Impairment of Long-Lived Assets	2,671	3,095
Income (Loss) from Operations	(28,954)	(31,001)
Depreciation of property, plant and equipment	4,183	3,369
Pension Service Cost	1,940	572
Identifiable Assets	364,656		368,542
Corporate Office [Member]
Segment Reporting Information [Line Items]
Operating Revenues	576	0
Income (Loss) from Operations before Amortization of Intangible Assets and Impairment of Long-Lived Assets	(14,636)	(14,073)
Amortization of Intangible Assets and Impairment of Long-Lived Assets	0	0
Income (Loss) from Operations	(14,636)	(14,073)
Depreciation of property, plant and equipment	149	153
Pension Service Cost	945	976
Identifiable Assets	92,331		$ 93,760
Intersegment Elimination [Member]
Segment Reporting Information [Line Items]
Operating Revenues	$ (812)	$ (584)