Business Segments (Information by Operating Segment) (Details 1) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2023	Sep. 30, 2023	Jun. 30, 2023	Mar. 31, 2023	Dec. 31, 2022	Sep. 30, 2022	Jun. 30, 2022	Mar. 31, 2022	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Segment Reporting Information [Line Items]
Operating Revenues	$ 1,166,813	$ 1,111,519	$ 1,104,999	$ 1,031,546	$ 1,064,032	$ 1,012,438	$ 933,302	$ 914,721	$ 4,414,877	$ 3,924,493	$ 3,185,974
Income (Loss) from Operations before Amortization of Intangible Assets and Impairment of Goodwill and Other Long-Lived Assets									218,498	271,739	168,185
Amortization of Intangible Assets and Impairment of Goodwill and Other Long-Lived Assets									149,105	187,841	90,810
Income (Loss) from Operations	40,794	$ (57,112)	$ 58,055	$ 27,656	(54,933)	$ 59,532	$ 39,328	$ 39,971	69,393	83,898	77,375
Equity in (Losses) Earnings of Affiliates, Net									(5,183)	(2,837)	17,914
Interest Expense, Net									(56,179)	(51,177)	(30,534)
Non-operating pension and postretirement benefit income, net									133,812	197,939	109,230
Gain (loss) on marketable equity securities, net									138,067	(139,589)	243,088
Other income, net									19,094	33,500	32,554
Income Before Income Taxes									299,004	121,734	449,627
Depreciation of property, plant and equipment									86,064	73,297	71,415
Pension service cost									33,787	32,567	22,991
Capital Expenditures									107,286	82,402	162,769
Identifiable Assets	4,197,459				4,098,991				4,197,459	4,098,991
Marketable equity securities	690,153				609,921				690,153	609,921
Investments in Affiliates	186,480				186,419				186,480	186,419
Prepaid Pension Cost	2,113,638				1,658,046				2,113,638	1,658,046
Total Assets	7,187,730				6,553,377				7,187,730	6,553,377
Amortization of Intangible Assets									50,039	58,851	57,870
Impairment of Long-Lived Assets									99,066	128,990	32,940
Operating Segments [Member] | Education [Member]
Segment Reporting Information [Line Items]
Operating Revenues									1,587,581	1,427,915	1,361,245
Income (Loss) from Operations before Amortization of Intangible Assets and Impairment of Goodwill and Other Long-Lived Assets									119,024	99,103	69,892
Amortization of Intangible Assets and Impairment of Goodwill and Other Long-Lived Assets									14,553	16,170	19,319
Income (Loss) from Operations									104,471	82,933	50,573
Depreciation of property, plant and equipment									38,187	34,114	32,113
Pension service cost									8,907	8,934	9,357
Capital Expenditures									36,760	46,878	100,780
Identifiable Assets	2,021,471				1,958,204				2,021,471	1,958,204
Amortization of Intangible Assets									14,076	16,170	16,001
Impairment of Long-Lived Assets									477	0	3,318
Operating Segments [Member] | Education [Member] | Kaplan Corporate and Other [Member]
Segment Reporting Information [Line Items]
Operating Revenues									11,012	9,853	9,612
Income (Loss) from Operations before Amortization of Intangible Assets and Impairment of Goodwill and Other Long-Lived Assets									(29,891)	(18,806)	(25,522)
Income (Loss) from Operations									(44,444)	(34,976)	(44,841)
Depreciation of property, plant and equipment									105	127	245
Pension service cost									698	708	812
Capital Expenditures									46	1,525	322
Identifiable Assets	45,991				51,676				45,991	51,676
Operating Segments [Member] | Education [Member] | Intersubsegment Eliminations [Member]
Segment Reporting Information [Line Items]
Operating Revenues									(10,047)	(10,209)	(6,551)
Income (Loss) from Operations before Amortization of Intangible Assets and Impairment of Goodwill and Other Long-Lived Assets									(29)	(45)	97
Income (Loss) from Operations									(29)	(45)	97
Operating Segments [Member] | Education [Member] | Kaplan International [Member] | Reportable Subsegments [Member]
Segment Reporting Information [Line Items]
Operating Revenues									966,879	816,239	726,875
Income (Loss) from Operations before Amortization of Intangible Assets and Impairment of Goodwill and Other Long-Lived Assets									87,530	72,066	33,457
Income (Loss) from Operations									87,530	72,066	33,457
Depreciation of property, plant and equipment									28,501	23,270	21,472
Pension service cost									325	270	291
Capital Expenditures									31,111	39,206	92,532
Identifiable Assets	1,537,989				1,454,445				1,537,989	1,454,445
Operating Segments [Member] | Education [Member] | Higher Education [Member] | Reportable Subsegments [Member]
Segment Reporting Information [Line Items]
Operating Revenues									326,961	310,407	322,240
Income (Loss) from Operations before Amortization of Intangible Assets and Impairment of Goodwill and Other Long-Lived Assets									38,942	24,819	24,941
Income (Loss) from Operations									38,942	24,819	24,941
Depreciation of property, plant and equipment									4,416	4,373	3,852
Pension service cost									3,737	3,842	4,440
Capital Expenditures									2,394	1,398	3,629
Identifiable Assets	187,972				187,034				187,972	187,034
Operating Segments [Member] | Education [Member] | Supplemental Education [Member] | Reportable Subsegments [Member]
Segment Reporting Information [Line Items]
Operating Revenues									292,776	301,625	309,069
Income (Loss) from Operations before Amortization of Intangible Assets and Impairment of Goodwill and Other Long-Lived Assets									22,472	21,069	36,919
Income (Loss) from Operations									22,472	21,069	36,919
Depreciation of property, plant and equipment									5,165	6,344	6,544
Pension service cost									4,147	4,114	3,814
Capital Expenditures									3,209	4,749	4,297
Identifiable Assets	249,519				265,049				249,519	265,049
Operating Segments [Member] | Television Broadcasting [Member]
Segment Reporting Information [Line Items]
Operating Revenues									472,436	535,651	494,177
Income (Loss) from Operations before Amortization of Intangible Assets and Impairment of Goodwill and Other Long-Lived Assets									139,388	207,319	154,862
Amortization of Intangible Assets and Impairment of Goodwill and Other Long-Lived Assets									5,450	5,440	5,440
Income (Loss) from Operations									133,938	201,879	149,422
Depreciation of property, plant and equipment									12,224	12,294	14,018
Pension service cost									3,331	3,554	3,575
Capital Expenditures									9,220	5,832	6,803
Identifiable Assets	419,557				431,084				419,557	431,084
Operating Segments [Member] | Manufacturing [Member]
Segment Reporting Information [Line Items]
Operating Revenues									447,910	486,643	458,125
Income (Loss) from Operations before Amortization of Intangible Assets and Impairment of Goodwill and Other Long-Lived Assets									47,010	54,079	36,926
Amortization of Intangible Assets and Impairment of Goodwill and Other Long-Lived Assets									63,803	20,372	52,974
Income (Loss) from Operations									(16,793)	33,707	(16,048)
Depreciation of property, plant and equipment									9,453	9,399	9,808
Pension service cost									1,115	1,104	1,282
Capital Expenditures									23,089	7,968	7,190
Identifiable Assets	431,712				486,487				431,712	486,487
Operating Segments [Member] | Healthcare [Member]
Segment Reporting Information [Line Items]
Operating Revenues									459,481	326,000	223,030
Income (Loss) from Operations before Amortization of Intangible Assets and Impairment of Goodwill and Other Long-Lived Assets									27,520	19,041	29,912
Amortization of Intangible Assets and Impairment of Goodwill and Other Long-Lived Assets									3,675	3,776	3,106
Income (Loss) from Operations									23,845	15,265	26,806
Depreciation of property, plant and equipment									5,475	3,781	1,313
Pension service cost									14,083	11,008	561
Capital Expenditures									12,992	2,745	3,671
Identifiable Assets	265,150				249,845				265,150	249,845
Operating Segments [Member] | Automotive [Member]
Segment Reporting Information [Line Items]
Operating Revenues									1,079,893	734,185	327,069
Income (Loss) from Operations before Amortization of Intangible Assets and Impairment of Goodwill and Other Long-Lived Assets									39,271	34,633	11,771
Amortization of Intangible Assets and Impairment of Goodwill and Other Long-Lived Assets									13	0	0
Income (Loss) from Operations									39,258	34,633	11,771
Depreciation of property, plant and equipment									5,177	3,709	2,156
Pension service cost									35	22	0
Capital Expenditures									10,140	3,606	31,124
Identifiable Assets	597,267				427,221				597,267	427,221
Operating Segments [Member] | Other Businesses [Member]
Segment Reporting Information [Line Items]
Operating Revenues									369,653	416,084	324,353
Income (Loss) from Operations before Amortization of Intangible Assets and Impairment of Goodwill and Other Long-Lived Assets									(98,115)	(86,270)	(76,153)
Amortization of Intangible Assets and Impairment of Goodwill and Other Long-Lived Assets									61,611	142,083	9,971
Income (Loss) from Operations									(159,726)	(228,353)	(86,124)
Depreciation of property, plant and equipment									14,941	9,392	11,376
Pension service cost									2,508	2,073	1,755
Capital Expenditures									15,053	15,352	13,176
Identifiable Assets	368,542				475,583				368,542	475,583
Corporate office [Member]
Segment Reporting Information [Line Items]
Operating Revenues									1,580	0	0
Income (Loss) from Operations before Amortization of Intangible Assets and Impairment of Goodwill and Other Long-Lived Assets									(55,600)	(56,166)	(59,025)
Amortization of Intangible Assets and Impairment of Goodwill and Other Long-Lived Assets									0	0	0
Income (Loss) from Operations									(55,600)	(56,166)	(59,025)
Depreciation of property, plant and equipment									607	608	631
Pension service cost									3,808	5,872	6,461
Capital Expenditures									32	21	25
Identifiable Assets	$ 93,760				$ 70,567				93,760	70,567
Intersegment Elimination [Member]
Segment Reporting Information [Line Items]
Operating Revenues									$ (3,657)	$ (1,985)	$ (2,025)