Business Segments (Information by Operating Segment) (Details 1) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2023	Mar. 31, 2022	Dec. 31, 2022
Segment Reporting Information [Line Items]
Operating Revenues	$ 1,031,546	$ 914,721
Income (Loss) from Operations before Amortization of Intangible Assets and Impairment of Long-Lived Assets	42,345	54,883
Amortization of Intangible Assets and Impairment of Long-Lived Assets	14,689	14,912
Income (Loss) from Operations	27,656	39,971
Equity in earnings of affiliates, net	4,661	2,604
Interest Expense, Net	(13,090)	(10,702)
Non-operating pension and postretirement benefit income, net	31,845	50,505
Gain on marketable equity securities, net	18,022	46,912
Other Income, Net	3,083	2,876
Income Before Income Taxes	72,177	132,166
Depreciation of property, plant and equipment	20,025	19,475
Pension Service Cost	9,243	6,031
Identifiable Assets	4,072,219		$ 4,127,829
Marketable equity securities	603,543		609,921
Investments in Affiliates	194,960		186,419
Prepaid Pension Cost	1,671,477		1,658,046
Total Assets	6,542,199		6,582,215
Amortization of Intangible Assets	13,944	14,912
Impairment of long-lived assets	745	0
Operating Segments [Member] | Education [Member]
Segment Reporting Information [Line Items]
Operating Revenues	378,041	358,012
Income (Loss) from Operations before Amortization of Intangible Assets and Impairment of Long-Lived Assets	27,456	24,558
Amortization of Intangible Assets and Impairment of Long-Lived Assets	4,416	4,146
Income (Loss) from Operations	23,040	20,412
Depreciation of property, plant and equipment	8,968	8,505
Pension Service Cost	2,198	2,536
Identifiable Assets	1,952,768		1,987,042
Amortization of Intangible Assets	3,939	4,146
Impairment of long-lived assets	477	0
Operating Segments [Member] | Education [Member] | Reportable Subsegments [Member] | Kaplan International [Member]
Segment Reporting Information [Line Items]
Operating Revenues	227,076	204,513
Income (Loss) from Operations before Amortization of Intangible Assets and Impairment of Long-Lived Assets	21,301	20,564
Income (Loss) from Operations	21,301	20,564
Depreciation of property, plant and equipment	6,330	5,755
Pension Service Cost	80	72
Identifiable Assets	1,449,063		1,479,833
Operating Segments [Member] | Education [Member] | Reportable Subsegments [Member] | Higher Education [Member]
Segment Reporting Information [Line Items]
Operating Revenues	76,345	75,808
Income (Loss) from Operations before Amortization of Intangible Assets and Impairment of Long-Lived Assets	6,661	5,037
Income (Loss) from Operations	6,661	5,037
Depreciation of property, plant and equipment	996	1,020
Pension Service Cost	922	1,081
Identifiable Assets	182,720		174,033
Operating Segments [Member] | Education [Member] | Reportable Subsegments [Member] | Supplemental Education [Member]
Segment Reporting Information [Line Items]
Operating Revenues	73,587	76,304
Income (Loss) from Operations before Amortization of Intangible Assets and Impairment of Long-Lived Assets	3,751	3,371
Income (Loss) from Operations	3,751	3,371
Depreciation of property, plant and equipment	1,509	1,639
Pension Service Cost	1,024	1,182
Identifiable Assets	256,050		268,499
Operating Segments [Member] | Education [Member] | Kaplan Corporate and Other [Member]
Segment Reporting Information [Line Items]
Operating Revenues	5,375	4,345
Income (Loss) from Operations before Amortization of Intangible Assets and Impairment of Long-Lived Assets	(4,416)	(4,433)
Income (Loss) from Operations	(8,832)	(8,579)
Depreciation of property, plant and equipment	133	91
Pension Service Cost	172	201
Identifiable Assets	64,935		64,677
Operating Segments [Member] | Education [Member] | Intersubsegment Eliminations [Member]
Segment Reporting Information [Line Items]
Operating Revenues	(4,342)	(2,958)
Income (Loss) from Operations before Amortization of Intangible Assets and Impairment of Long-Lived Assets	159	19
Income (Loss) from Operations	159	19
Operating Segments [Member] | Television Broadcasting [Member]
Segment Reporting Information [Line Items]
Operating Revenues	112,877	123,419
Income (Loss) from Operations before Amortization of Intangible Assets and Impairment of Long-Lived Assets	29,945	41,258
Amortization of Intangible Assets and Impairment of Long-Lived Assets	1,362	1,360
Income (Loss) from Operations	28,583	39,898
Depreciation of property, plant and equipment	3,036	3,289
Pension Service Cost	860	926
Identifiable Assets	424,185		431,084
Operating Segments [Member] | Manufacturing [Member]
Segment Reporting Information [Line Items]
Operating Revenues	114,584	115,940
Income (Loss) from Operations before Amortization of Intangible Assets and Impairment of Long-Lived Assets	12,190	15,138
Amortization of Intangible Assets and Impairment of Long-Lived Assets	4,862	5,163
Income (Loss) from Operations	7,328	9,975
Depreciation of property, plant and equipment	2,282	2,428
Pension Service Cost	275	328
Identifiable Assets	488,192		486,487
Operating Segments [Member] | Healthcare [Member]
Segment Reporting Information [Line Items]
Operating Revenues	102,059	67,255
Income (Loss) from Operations before Amortization of Intangible Assets and Impairment of Long-Lived Assets	3,890	7,288
Amortization of Intangible Assets and Impairment of Long-Lived Assets	954	929
Income (Loss) from Operations	2,936	6,359
Depreciation of property, plant and equipment	1,104	410
Pension Service Cost	4,357	186
Identifiable Assets	255,542		249,845
Operating Segments [Member] | Automotive [Member]
Segment Reporting Information [Line Items]
Operating Revenues	232,561	150,967
Income (Loss) from Operations before Amortization of Intangible Assets and Impairment of Long-Lived Assets	10,843	7,078
Amortization of Intangible Assets and Impairment of Long-Lived Assets	0	0
Income (Loss) from Operations	10,843	7,078
Depreciation of property, plant and equipment	1,113	777
Pension Service Cost	5	6
Identifiable Assets	440,036		427,221
Operating Segments [Member] | Other Businesses [Member]
Segment Reporting Information [Line Items]
Operating Revenues	92,008	99,617
Income (Loss) from Operations before Amortization of Intangible Assets and Impairment of Long-Lived Assets	(27,906)	(27,430)
Amortization of Intangible Assets and Impairment of Long-Lived Assets	3,095	3,314
Income (Loss) from Operations	(31,001)	(30,744)
Depreciation of property, plant and equipment	3,369	3,915
Pension Service Cost	572	520
Identifiable Assets	445,409		475,583
Corporate Office [Member]
Segment Reporting Information [Line Items]
Operating Revenues	0	0
Income (Loss) from Operations before Amortization of Intangible Assets and Impairment of Long-Lived Assets	(14,073)	(13,007)
Amortization of Intangible Assets and Impairment of Long-Lived Assets	0	0
Income (Loss) from Operations	(14,073)	(13,007)
Depreciation of property, plant and equipment	153	151
Pension Service Cost	976	1,529
Identifiable Assets	66,087		$ 70,567
Intersegment Elimination [Member]
Segment Reporting Information [Line Items]
Operating Revenues	$ (584)	$ (489)