Business Segments (Information by Operating Segment) (Details 1) - USD ($) $ in Thousands		3 Months Ended
		Mar. 31, 2026	Mar. 31, 2025	Dec. 31, 2025
Segment Reporting Information [Line Items]
Operating Revenues		$ 1,235,992	$ 1,165,915
Depreciation Expense		18,394	20,554
Amortization of Intangible Assets		(6,055)	(7,824)
Impairment of Goodwill and Asset Group Held for Sale		(19,029)	0
Income from Operations		57,833	47,473
Equity in earnings (losses) of affiliates, net		34,850	(8,428)
Interest Expense, Net		(13,754)	(79,777)
Non-operating pension and postretirement benefit income, net		31,073	34,617
(Loss) gain on marketable equity securities, net		(68,923)	43,801
Other expense, net		(428)	(4,065)
Income Before Income Taxes		40,651	33,621
Capital Expenditures		20,869	14,103
Investments in Marketable Equity Securities		966,719		$ 1,081,938
Investments in Affiliates		237,053		229,565
Prepaid Pension Cost		2,792,300		2,772,394
Total Assets		8,180,489		8,395,713
Operating Segments [Member] | Reportable Segment, Aggregation before Other Operating Segment [Member]
Segment Reporting Information [Line Items]
Operating Revenues		1,154,030	1,081,022
Cost of Revenue	[1]	616,320	576,246
Payroll and Fringe Benefits Expense	[2]	164,934	160,513
Occupancy Expense		29,409	29,793
Advertising and Marketing Expense		19,429	19,220
Networking and Programming Expenses		30,123	31,357
Management Services	[3]	2,292	2,052
Other Segment Items	[4]	145,573	134,734
EBITDAP		145,950	127,107
Pension Service Cost		9,060	9,744
Depreciation Expense		15,284	16,610
Income (loss) from Operations before Amortization of Intangible Assets and Impairment of Goodwill and Asset Group Held for Sale		121,606	100,753
Capital Expenditures		17,372	9,409
Identifiable Assets		3,759,531		3,875,019
Operating Segments [Member] | Education [Member]
Segment Reporting Information [Line Items]
Operating Revenues		440,479	424,731
Cost of Revenue	[1]	167,427	166,087
Payroll and Fringe Benefits Expense	[2]	117,657	113,320
Occupancy Expense		27,377	27,922
Advertising and Marketing Expense		19,429	19,220
Other Segment Items	[5]	46,371	44,043
EBITDAP		62,218	54,139
Pension Service Cost		4,439	4,223
Depreciation Expense		6,054	7,764
Income (loss) from Operations before Amortization of Intangible Assets and Impairment of Goodwill and Asset Group Held for Sale		51,725	42,152
Capital Expenditures		4,450	4,741
Identifiable Assets		1,867,647		2,008,574
Operating Segments [Member] | Education [Member] | Kaplan Corporate and Other [Member]
Segment Reporting Information [Line Items]
Operating Revenues		271	12
Payroll and Fringe Benefits Expense	[2]	4,502	5,010
Occupancy Expense		374	63
Advertising and Marketing Expense		93	128
Other Segment Items	[5]	(764)	1,065
EBITDAP		(3,934)	(6,254)
Pension Service Cost		407	388
Depreciation Expense		9	6
Income (loss) from Operations before Amortization of Intangible Assets and Impairment of Goodwill and Asset Group Held for Sale		(4,350)	(6,648)
Capital Expenditures		0	0
Identifiable Assets		38,053		34,973
Operating Segments [Member] | Education [Member] | Intersubsegment Eliminations [Member]
Segment Reporting Information [Line Items]
Operating Revenues		(695)	(427)
Cost of Revenue	[1]	(339)	(427)
Payroll and Fringe Benefits Expense	[2]	(74)
Occupancy Expense		(267)
Other Segment Items	[5]	266	37
EBITDAP		(281)	(37)
Income (loss) from Operations before Amortization of Intangible Assets and Impairment of Goodwill and Asset Group Held for Sale		(281)	(37)
Operating Segments [Member] | Education [Member] | Kaplan International [Member] | Reportable Subsegments [Member]
Segment Reporting Information [Line Items]
Operating Revenues		271,636	261,256
Cost of Revenue	[1]	90,001	88,097
Payroll and Fringe Benefits Expense	[2]	76,392	70,666
Occupancy Expense		26,278	27,025
Advertising and Marketing Expense		8,199	8,185
Other Segment Items	[6]	34,285	30,532
EBITDAP		36,481	36,751
Pension Service Cost		126	140
Depreciation Expense		4,968	6,549
Income (loss) from Operations before Amortization of Intangible Assets and Impairment of Goodwill and Asset Group Held for Sale		31,387	30,062
Capital Expenditures		3,300	2,787
Identifiable Assets		1,431,048		1,551,682
Operating Segments [Member] | Education [Member] | Higher Education [Member] | Reportable Subsegments [Member]
Segment Reporting Information [Line Items]
Operating Revenues		92,403	88,487
Cost of Revenue	[1]	66,243	66,662
Payroll and Fringe Benefits Expense	[2]	3,805	4,477
Occupancy Expense		158	176
Advertising and Marketing Expense		1,920	1,877
Other Segment Items	[7]	401	224
EBITDAP		19,876	15,071
Pension Service Cost		1,920	1,808
Depreciation Expense		267	456
Income (loss) from Operations before Amortization of Intangible Assets and Impairment of Goodwill and Asset Group Held for Sale		17,689	12,807
Capital Expenditures		815	173
Identifiable Assets		164,418		174,738
Operating Segments [Member] | Education [Member] | Supplemental Education [Member] | Reportable Subsegments [Member]
Segment Reporting Information [Line Items]
Operating Revenues		76,864	75,403
Cost of Revenue	[1]	11,522	11,755
Payroll and Fringe Benefits Expense	[2]	33,032	33,167
Occupancy Expense		834	658
Advertising and Marketing Expense		9,217	9,030
Other Segment Items	[8]	12,183	12,185
EBITDAP		10,076	8,608
Pension Service Cost		1,986	1,887
Depreciation Expense		810	753
Income (loss) from Operations before Amortization of Intangible Assets and Impairment of Goodwill and Asset Group Held for Sale		7,280	5,968
Capital Expenditures		335	1,781
Identifiable Assets		234,128		247,181
Operating Segments [Member] | Television Broadcasting [Member]
Segment Reporting Information [Line Items]
Operating Revenues		111,553	103,554
Payroll and Fringe Benefits Expense	[2]	27,285	27,764
Networking and Programming Expenses		30,123	31,357
Other Segment Items	[9]	15,018	14,628
EBITDAP		39,127	29,805
Pension Service Cost		1,488	1,419
Depreciation Expense		2,336	2,628
Income (loss) from Operations before Amortization of Intangible Assets and Impairment of Goodwill and Asset Group Held for Sale		35,303	25,758
Capital Expenditures		2,936	198
Identifiable Assets		388,564		393,097
Operating Segments [Member] | Healthcare [Member]
Segment Reporting Information [Line Items]
Operating Revenues		209,340	173,741
Cost of Revenue	[1]	133,936	100,115
Other Segment Items	[10]	54,082	50,406
EBITDAP		21,322	23,220
Pension Service Cost		1,886	2,999
Depreciation Expense		1,914	1,786
Income (loss) from Operations before Amortization of Intangible Assets and Impairment of Goodwill and Asset Group Held for Sale		17,522	18,435
Capital Expenditures		2,165	617
Identifiable Assets		380,712		355,627
Operating Segments [Member] | Healthcare [Member] | Other Healthcare [Member]
Segment Reporting Information [Line Items]
Operating Revenues		91,559	83,493
Cost of Revenue	[1]	42,792	36,141
Other Segment Items	[10]	34,071	33,984
EBITDAP		14,696	13,368
Pension Service Cost		1,886	2,999
Depreciation Expense		1,621	1,610
Income (loss) from Operations before Amortization of Intangible Assets and Impairment of Goodwill and Asset Group Held for Sale		11,189	8,759
Capital Expenditures		598	319
Identifiable Assets		183,373		227,457
Operating Segments [Member] | Healthcare [Member] | CSI [Member] | Reportable Subsegments [Member]
Segment Reporting Information [Line Items]
Operating Revenues		117,781	90,248
Cost of Revenue	[1]	91,144	63,974
Other Segment Items	[11]	20,011	16,422
EBITDAP		6,626	9,852
Pension Service Cost		0	0
Depreciation Expense		293	176
Income (loss) from Operations before Amortization of Intangible Assets and Impairment of Goodwill and Asset Group Held for Sale		6,333	9,676
Capital Expenditures		1,567	298
Identifiable Assets		197,339		128,170
Operating Segments [Member] | Manufacturing [Member]
Segment Reporting Information [Line Items]
Operating Revenues		125,034	98,005
Cost of Revenue	[1]	88,214	69,737
Other Segment Items	[12]	20,712	16,578
EBITDAP		16,108	11,690
Pension Service Cost		1,230	1,076
Depreciation Expense		3,135	2,703
Income (loss) from Operations before Amortization of Intangible Assets and Impairment of Goodwill and Asset Group Held for Sale		11,743	7,911
Capital Expenditures		1,688	3,373
Identifiable Assets		542,933		535,006
Operating Segments [Member] | Automotive [Member]
Segment Reporting Information [Line Items]
Operating Revenues		267,624	280,991
Cost of Revenue	[1]	226,743	240,307
Payroll and Fringe Benefits Expense	[2]	19,992	19,429
Occupancy Expense		2,032	1,871
Management Services	[3]	2,292	2,052
Other Segment Items	[13]	9,390	9,079
EBITDAP		7,175	8,253
Pension Service Cost		17	27
Depreciation Expense		1,845	1,729
Income (loss) from Operations before Amortization of Intangible Assets and Impairment of Goodwill and Asset Group Held for Sale		5,313	6,497
Capital Expenditures		6,133	480
Identifiable Assets		579,675		582,715
Operating Segments [Member] | Other Businesses [Member]
Segment Reporting Information [Line Items]
Income (loss) from Operations before Amortization of Intangible Assets and Impairment of Goodwill and Asset Group Held for Sale	[14]	(23,600)	(29,447)
Identifiable Assets		345,737		357,408
Operating Segments [Member] | Other Businesses and Corporate Office [Member]
Segment Reporting Information [Line Items]
Operating Revenues	[15]	82,599	85,517
Capital Expenditures	[16]	3,497	4,694
Corporate Office [Member]
Segment Reporting Information [Line Items]
Income (loss) from Operations before Amortization of Intangible Assets and Impairment of Goodwill and Asset Group Held for Sale		(15,089)	(16,009)
Identifiable Assets		79,149		$ 79,389
Intersegment Elimination [Member]
Segment Reporting Information [Line Items]
Operating Revenues		$ (637)	$ (624)

[1] Cost of revenue reflects the amounts reported and provided to the CODM and does not necessarily reconcile to the Company's Consolidated Statement of Operations or align across reportable segments. Cost of revenue excludes charges related to depreciation, which is shown separately above.

[2] Excludes pension service cost, which is shown separately above. Excludes any payroll and related benefits costs captured in cost of revenue.

[3] Management and operating services provided by Christopher J. Ourisman and his team of industry professionals.

[4] Other segment items for each reportable segment include:

[5] Education (includes Kaplan International, Kaplan Higher Education and Kaplan Supplemental Education) - training and employment expense, travel meals and entertainment expense, operating fees and other general and administrative (G&A) expenses.

[6] Kaplan international - travel meals and entertainment expense, training and employment expense, operating fees and other G&A expenses.

[7] Higher education - training and employment expense, operating fees and other G&A expenses.

[8] Supplemental education - training and employment expense, operating fees and other G&A expenses.

[9] Television Broadcasting - other broadcast expenses, facilities expenses, third-party commission costs and other selling, general and administrative (SG&A) expenses.

[10] Healthcare - indirect costs (e.g. payroll and benefits expenses, general and administrative expenses) and other SG&A expenses.

[11] Other segment items for CSI include indirect costs (e.g. payroll and benefits expenses, general and administrative expenses) and other SG&A expenses.

[12] Manufacturing - payroll and fringe benefits expense (SG&A) and other SG&A expenses.

[13] Automotive - advertising and marketing expense and other G&A expenses.

[14] Profit or loss from operating segments below the quantitative thresholds attributable to Other Businesses as described above. These operating segments did not meet any of the quantitative thresholds for determining reportable segments.

[15] Revenue from segments below the quantitative thresholds is attributable to Other Businesses and the Corporate Office, as described above. None of these operating segments meet the quantitative thresholds for determining reportable segments.

[16] Capital Expenditures from operating segments below the quantitative thresholds are attributable to Other Businesses and the Corporate Office, as described above. None of these operating segments meet the quantitative thresholds for determining reportable segments.