Business Segments (Information by Operating Segment) (Details 1) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2024	Jun. 30, 2023	Jun. 30, 2024	Jun. 30, 2023	Dec. 31, 2023
Segment Reporting Information [Line Items]
Operating Revenues	$ 1,185,280	$ 1,104,999	$ 2,337,942	$ 2,136,545
Income (Loss) from Operations before Amortization of Intangible Assets and Impairment of Goodwill and Other Long-Lived Assets	62,256	71,359	108,449	113,704
Amortization of Intangible Assets and Impairment of Goodwill and Other Long-Lived Assets	36,345	13,304	47,096	27,993
Income (Loss) from Operations	25,911	58,055	61,353	85,711
Equity in earnings (losses) of affiliates, net	2,560	(6,115)	4,891	(1,454)
Interest Expense, Net	(89,272)	(10,226)	(106,422)	(23,316)
Non-operating pension and postretirement benefit income, net	24,655	29,815	67,072	61,660
Gain on marketable equity securities, net	19,628	78,648	123,780	96,670
Other Income, Net	1,791	15,794	3,438	18,877
(Loss) Income Before Income Taxes	(14,727)	165,971	154,112	238,148
Depreciation of property, plant and equipment	22,173	21,103	44,700	41,128
Pension Service Cost	14,071	7,573	28,105	16,816
Capital Expenditures	20,764	22,525	42,237	44,839
Identifiable Assets	4,105,913		4,105,913		$ 4,197,459
Marketable equity securities	813,444		813,444		690,153
Investments in Affiliates	185,500		185,500		186,480
Prepaid Pension Cost	2,129,196		2,129,196		2,113,638
Total Assets	7,234,053		7,234,053		7,187,730
Amortization of Intangible Assets	10,058	13,304	20,809	27,248
Impairment of goodwill and other long-lived assets	26,287	0	26,287	745
Operating Segments [Member] | Education [Member]
Segment Reporting Information [Line Items]
Operating Revenues	422,899	402,227	845,497	780,268
Income (Loss) from Operations before Amortization of Intangible Assets and Impairment of Goodwill and Other Long-Lived Assets	38,149	34,100	71,710	61,556
Amortization of Intangible Assets and Impairment of Goodwill and Other Long-Lived Assets	2,872	3,984	5,846	8,400
Income (Loss) from Operations	35,277	30,116	65,864	53,156
Depreciation of property, plant and equipment	8,855	9,460	18,160	18,428
Pension Service Cost	4,712	2,256	8,822	4,454
Capital Expenditures	5,138	7,166	12,657	15,200
Identifiable Assets	1,924,838		1,924,838		2,021,471
Amortization of Intangible Assets	2,872	3,984	5,846	7,923
Impairment of goodwill and other long-lived assets	0	0	0	477
Operating Segments [Member] | Education [Member] | Kaplan Corporate and Other [Member]
Segment Reporting Information [Line Items]
Operating Revenues	2,993	2,887	5,581	5,259
Income (Loss) from Operations before Amortization of Intangible Assets and Impairment of Goodwill and Other Long-Lived Assets	(8,055)	(7,824)	(15,640)	(12,662)
Income (Loss) from Operations	(10,927)	(11,808)	(21,486)	(21,062)
Depreciation of property, plant and equipment	22	25	49	52
Pension Service Cost	407	229	755	401
Capital Expenditures	0	22	0	22
Identifiable Assets	46,912		46,912		45,991
Operating Segments [Member] | Education [Member] | Intersubsegment Eliminations [Member]
Segment Reporting Information [Line Items]
Operating Revenues	(1,294)	(3,230)	(3,326)	(6,565)
Income (Loss) from Operations before Amortization of Intangible Assets and Impairment of Goodwill and Other Long-Lived Assets	354	(134)	89	25
Income (Loss) from Operations	354	(134)	89	25
Operating Segments [Member] | Education [Member] | Kaplan International [Member] | Reportable Subsegments [Member]
Segment Reporting Information [Line Items]
Operating Revenues	267,026	237,663	536,824	464,739
Income (Loss) from Operations before Amortization of Intangible Assets and Impairment of Goodwill and Other Long-Lived Assets	25,824	20,751	57,136	42,052
Income (Loss) from Operations	25,824	20,751	57,136	42,052
Depreciation of property, plant and equipment	7,177	6,903	14,533	13,233
Pension Service Cost	166	81	329	161
Capital Expenditures	4,503	6,161	11,520	13,302
Identifiable Assets	1,440,409		1,440,409		1,537,989
Operating Segments [Member] | Education [Member] | Higher Education [Member] | Reportable Subsegments [Member]
Segment Reporting Information [Line Items]
Operating Revenues	81,041	90,291	161,163	168,632
Income (Loss) from Operations before Amortization of Intangible Assets and Impairment of Goodwill and Other Long-Lived Assets	14,354	17,795	19,873	24,878
Income (Loss) from Operations	14,354	17,795	19,873	24,878
Depreciation of property, plant and equipment	799	1,071	1,702	2,173
Pension Service Cost	2,045	923	3,826	1,845
Capital Expenditures	174	566	233	638
Identifiable Assets	205,601		205,601		187,972
Operating Segments [Member] | Education [Member] | Supplemental Education [Member] | Reportable Subsegments [Member]
Segment Reporting Information [Line Items]
Operating Revenues	73,133	74,616	145,255	148,203
Income (Loss) from Operations before Amortization of Intangible Assets and Impairment of Goodwill and Other Long-Lived Assets	5,672	3,512	10,252	7,263
Income (Loss) from Operations	5,672	3,512	10,252	7,263
Depreciation of property, plant and equipment	857	1,461	1,876	2,970
Pension Service Cost	2,094	1,023	3,912	2,047
Capital Expenditures	461	417	904	1,238
Identifiable Assets	231,916		231,916		249,519
Operating Segments [Member] | Television Broadcasting [Member]
Segment Reporting Information [Line Items]
Operating Revenues	115,478	118,829	228,536	231,706
Income (Loss) from Operations before Amortization of Intangible Assets and Impairment of Goodwill and Other Long-Lived Assets	32,488	34,553	63,471	64,498
Amortization of Intangible Assets and Impairment of Goodwill and Other Long-Lived Assets	1,360	1,363	2,710	2,725
Income (Loss) from Operations	31,128	33,190	60,761	61,773
Depreciation of property, plant and equipment	2,870	3,087	5,738	6,123
Pension Service Cost	1,416	805	3,055	1,665
Capital Expenditures	1,708	1,680	3,337	3,177
Identifiable Assets	413,786		413,786		419,557
Operating Segments [Member] | Manufacturing [Member]
Segment Reporting Information [Line Items]
Operating Revenues	103,626	120,082	205,529	234,666
Income (Loss) from Operations before Amortization of Intangible Assets and Impairment of Goodwill and Other Long-Lived Assets	6,913	16,314	13,102	28,504
Amortization of Intangible Assets and Impairment of Goodwill and Other Long-Lived Assets	2,648	4,332	5,768	9,194
Income (Loss) from Operations	4,265	11,982	7,334	19,310
Depreciation of property, plant and equipment	2,694	2,287	5,409	4,569
Pension Service Cost	292	281	919	556
Capital Expenditures	2,608	4,805	8,268	10,591
Identifiable Assets	420,789		420,789		431,712
Operating Segments [Member] | Healthcare [Member]
Segment Reporting Information [Line Items]
Operating Revenues	147,528	113,282	275,729	215,341
Income (Loss) from Operations before Amortization of Intangible Assets and Impairment of Goodwill and Other Long-Lived Assets	13,335	9,259	20,062	13,149
Amortization of Intangible Assets and Impairment of Goodwill and Other Long-Lived Assets	598	882	1,234	1,836
Income (Loss) from Operations	12,737	8,377	18,828	11,313
Depreciation of property, plant and equipment	1,683	1,287	3,277	2,391
Pension Service Cost	4,851	2,685	9,609	7,042
Capital Expenditures	2,890	3,446	4,826	5,153
Identifiable Assets	293,406		293,406		265,150
Operating Segments [Member] | Automotive [Member]
Segment Reporting Information [Line Items]
Operating Revenues	308,814	260,672	612,654	493,233
Income (Loss) from Operations before Amortization of Intangible Assets and Impairment of Goodwill and Other Long-Lived Assets	10,208	9,460	19,860	20,303
Amortization of Intangible Assets and Impairment of Goodwill and Other Long-Lived Assets	5	0	5	0
Income (Loss) from Operations	10,203	9,460	19,855	20,303
Depreciation of property, plant and equipment	1,716	1,148	3,429	2,261
Pension Service Cost	42	5	57	10
Capital Expenditures	1,165	1,854	2,369	4,103
Identifiable Assets	616,260		616,260		597,267
Operating Segments [Member] | Other Businesses [Member]
Segment Reporting Information [Line Items]
Operating Revenues	86,991	90,449	170,289	182,457
Income (Loss) from Operations before Amortization of Intangible Assets and Impairment of Goodwill and Other Long-Lived Assets	(24,100)	(21,118)	(50,383)	(49,024)
Amortization of Intangible Assets and Impairment of Goodwill and Other Long-Lived Assets	28,862	2,743	31,533	5,838
Income (Loss) from Operations	(52,962)	(23,861)	(81,916)	(54,862)
Depreciation of property, plant and equipment	4,204	3,681	8,387	7,050
Pension Service Cost	1,674	613	3,614	1,185
Capital Expenditures	6,898	3,574	10,375	6,612
Identifiable Assets	333,875		333,875		368,542
Corporate Office [Member]
Segment Reporting Information [Line Items]
Operating Revenues	575	850	1,151	850
Income (Loss) from Operations before Amortization of Intangible Assets and Impairment of Goodwill and Other Long-Lived Assets	(14,737)	(11,209)	(29,373)	(25,282)
Amortization of Intangible Assets and Impairment of Goodwill and Other Long-Lived Assets	0	0	0	0
Income (Loss) from Operations	(14,737)	(11,209)	(29,373)	(25,282)
Depreciation of property, plant and equipment	151	153	300	306
Pension Service Cost	1,084	928	2,029	1,904
Capital Expenditures	357	0	405	3
Identifiable Assets	102,959		102,959		$ 93,760
Intersegment Elimination [Member]
Segment Reporting Information [Line Items]
Operating Revenues	$ (631)	$ (1,392)	$ (1,443)	$ (1,976)