Business Segments (Information by Operating Segment) (Details 2) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Segment Reporting Information [Line Items]
Operating Revenues	$ 3,924,493	$ 3,185,974	$ 2,889,121
Income (Loss) from Operations before Amortization of Intangible Assets and Impairment of Goodwill and Other Long-Lived Assets	271,739	168,185	187,357
Amortization of Intangible Assets and Impairment of Goodwill and Other Long-Lived Assets	187,841	90,810	86,950
Income (Loss) from Operations	83,898	77,375	100,407
Equity in (Losses) Earnings of Affiliates, Net	(2,837)	17,914	6,664
Interest Expense, Net	(51,177)	(30,534)	(34,439)
Non-operating pension and postretirement benefit income, net	197,939	109,230	59,315
(Loss) gain on marketable equity securities, net	(139,589)	243,088	60,787
Other income, net	33,500	32,554	214,534
Income Before Income Taxes	121,734	449,627	407,268
Depreciation of property, plant and equipment	73,297	71,415	74,257
Pension service cost	32,567	22,991	22,656
Capital Expenditures	82,402	162,769	65,874
Identifiable Assets	4,127,829	4,153,570
Marketable equity securities	609,921	809,997
Investments in Affiliates	186,419	155,444
Prepaid Pension Cost	1,658,046	2,306,514
Total Assets	6,582,215	7,425,525
Amortization of Intangible Assets	58,851	57,870	56,780
Impairment of Long-Lived Assets	128,990	32,940	30,170
Operating Segments [Member] | Education [Member]
Segment Reporting Information [Line Items]
Operating Revenues	1,427,915	1,361,245	1,305,713
Income (Loss) from Operations before Amortization of Intangible Assets and Impairment of Goodwill and Other Long-Lived Assets	99,103	69,892	41,056
Amortization of Intangible Assets and Impairment of Goodwill and Other Long-Lived Assets	16,170	19,319	29,452
Income (Loss) from Operations	82,933	50,573	11,604
Depreciation of property, plant and equipment	34,114	32,113	31,759
Pension service cost	8,934	9,357	10,024
Capital Expenditures	46,878	100,780	33,553
Identifiable Assets	1,987,042	2,026,782
Amortization of Intangible Assets	16,170	16,001	17,174
Impairment of Long-Lived Assets	0	3,318	12,278
Operating Segments [Member] | Education [Member] | Kaplan Corporate and Other [Member]
Segment Reporting Information [Line Items]
Operating Revenues	18,752	14,759	12,643
Income (Loss) from Operations before Amortization of Intangible Assets and Impairment of Goodwill and Other Long-Lived Assets	(18,018)	(24,715)	(18,266)
Income (Loss) from Operations	(34,188)	(44,034)	(47,718)
Depreciation of property, plant and equipment	393	439	391
Pension service cost	708	812	1,234
Capital Expenditures	1,525	322	204
Identifiable Assets	64,677	58,248
Operating Segments [Member] | Education [Member] | Intersubsegment Eliminations [Member]
Segment Reporting Information [Line Items]
Operating Revenues	(12,837)	(7,312)	(4,004)
Income (Loss) from Operations before Amortization of Intangible Assets and Impairment of Goodwill and Other Long-Lived Assets	(45)	97	5
Income (Loss) from Operations	(45)	97	5
Operating Segments [Member] | Education [Member] | Kaplan International [Member] | Reportable Subsegments [Member]
Segment Reporting Information [Line Items]
Operating Revenues	816,239	726,875	653,892
Income (Loss) from Operations before Amortization of Intangible Assets and Impairment of Goodwill and Other Long-Lived Assets	72,066	33,457	15,248
Income (Loss) from Operations	72,066	33,457	15,248
Depreciation of property, plant and equipment	23,270	21,472	19,562
Pension service cost	270	291	433
Capital Expenditures	39,206	92,532	24,085
Identifiable Assets	1,479,833	1,493,868
Operating Segments [Member] | Education [Member] | Higher Education [Member] | Reportable Subsegments [Member]
Segment Reporting Information [Line Items]
Operating Revenues	304,136	317,854	316,095
Income (Loss) from Operations before Amortization of Intangible Assets and Impairment of Goodwill and Other Long-Lived Assets	24,031	24,134	24,364
Income (Loss) from Operations	24,031	24,134	24,364
Depreciation of property, plant and equipment	4,107	3,658	3,082
Pension service cost	3,842	4,440	4,150
Capital Expenditures	1,398	3,629	3,234
Identifiable Assets	174,033	187,789
Operating Segments [Member] | Education [Member] | Supplemental Education [Member] | Reportable Subsegments [Member]
Segment Reporting Information [Line Items]
Operating Revenues	301,625	309,069	327,087
Income (Loss) from Operations before Amortization of Intangible Assets and Impairment of Goodwill and Other Long-Lived Assets	21,069	36,919	19,705
Income (Loss) from Operations	21,069	36,919	19,705
Depreciation of property, plant and equipment	6,344	6,544	8,724
Pension service cost	4,114	3,814	4,207
Capital Expenditures	4,749	4,297	6,030
Identifiable Assets	268,499	286,877
Operating Segments [Member] | Television Broadcasting [Member]
Segment Reporting Information [Line Items]
Operating Revenues	535,651	494,177	525,212
Income (Loss) from Operations before Amortization of Intangible Assets and Impairment of Goodwill and Other Long-Lived Assets	207,319	154,862	199,938
Amortization of Intangible Assets and Impairment of Goodwill and Other Long-Lived Assets	5,440	5,440	5,440
Income (Loss) from Operations	201,879	149,422	194,498
Depreciation of property, plant and equipment	12,294	14,018	13,830
Pension service cost	3,554	3,575	3,263
Capital Expenditures	5,832	6,803	13,470
Identifiable Assets	431,084	448,627
Operating Segments [Member] | Manufacturing [Member]
Segment Reporting Information [Line Items]
Operating Revenues	486,643	458,125	416,137
Income (Loss) from Operations before Amortization of Intangible Assets and Impairment of Goodwill and Other Long-Lived Assets	54,079	36,926	40,427
Amortization of Intangible Assets and Impairment of Goodwill and Other Long-Lived Assets	20,372	52,974	28,099
Income (Loss) from Operations	33,707	(16,048)	12,328
Depreciation of property, plant and equipment	9,399	9,808	10,333
Pension service cost	1,104	1,282	1,424
Capital Expenditures	7,968	7,190	8,034
Identifiable Assets	486,487	486,304
Operating Segments [Member] | Graham Healthcare Group [Member]
Segment Reporting Information [Line Items]
Operating Revenues	326,000	223,030	198,196
Income (Loss) from Operations before Amortization of Intangible Assets and Impairment of Goodwill and Other Long-Lived Assets	19,041	29,912	30,327
Amortization of Intangible Assets and Impairment of Goodwill and Other Long-Lived Assets	3,776	3,106	4,220
Income (Loss) from Operations	15,265	26,806	26,107
Depreciation of property, plant and equipment	3,781	1,313	1,665
Pension service cost	11,008	561	543
Capital Expenditures	2,745	3,671	2,481
Identifiable Assets	249,845	194,823
Operating Segments [Member] | Automotive [Member]
Segment Reporting Information [Line Items]
Operating Revenues	734,185	327,069	258,144
Income (Loss) from Operations before Amortization of Intangible Assets and Impairment of Goodwill and Other Long-Lived Assets	34,633	11,771	502
Amortization of Intangible Assets and Impairment of Goodwill and Other Long-Lived Assets	0	0	6,698
Income (Loss) from Operations	34,633	11,771	(6,196)
Depreciation of property, plant and equipment	3,709	2,156	2,017
Pension service cost	22	0	0
Capital Expenditures	3,606	31,124	3,181
Identifiable Assets	427,221	238,200
Operating Segments [Member] | Other Businesses [Member]
Segment Reporting Information [Line Items]
Operating Revenues	416,084	324,353	187,347
Income (Loss) from Operations before Amortization of Intangible Assets and Impairment of Goodwill and Other Long-Lived Assets	(86,270)	(76,153)	(72,915)
Amortization of Intangible Assets and Impairment of Goodwill and Other Long-Lived Assets	142,083	9,971	13,041
Income (Loss) from Operations	(228,353)	(86,124)	(85,956)
Depreciation of property, plant and equipment	9,392	11,376	13,947
Pension service cost	2,073	1,755	1,698
Capital Expenditures	15,352	13,176	5,075
Identifiable Assets	475,583	689,872
Corporate office [Member]
Segment Reporting Information [Line Items]
Operating Revenues	0	0	0
Income (Loss) from Operations before Amortization of Intangible Assets and Impairment of Goodwill and Other Long-Lived Assets	(56,166)	(59,025)	(51,978)
Amortization of Intangible Assets and Impairment of Goodwill and Other Long-Lived Assets	0	0	0
Income (Loss) from Operations	(56,166)	(59,025)	(51,978)
Depreciation of property, plant and equipment	608	631	706
Pension service cost	5,872	6,461	5,704
Capital Expenditures	21	25	80
Identifiable Assets	70,567	68,962
Intersegment Elimination [Member]
Segment Reporting Information [Line Items]
Operating Revenues	$ (1,985)	$ (2,025)	$ (1,628)