Business Segments (Information by Operating Segment) (Details 1) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022	Dec. 31, 2022
Segment Reporting Information [Line Items]
Operating Revenues	$ 1,111,519	$ 1,012,438	$ 3,248,064	$ 2,860,461
Income (Loss) from Operations before Amortization of Intangible Assets and Impairment of Goodwill and Other Long-Lived Assets	52,968	74,167	166,672	183,267
Amortization of Intangible Assets and Impairment of Goodwill and Other Long-Lived Assets	110,080	14,635	138,073	44,436
Income (Loss) from Operations	(57,112)	59,532	28,599	138,831
Equity in (losses) earnings of affiliates, net	(791)	(1,111)	(2,245)	2,920
Interest Expense, Net	(9,824)	(10,776)	(33,140)	(36,755)
Non-operating pension and postretirement benefit income, net	35,653	50,687	97,313	152,063
Gain (loss) on marketable equity securities, net	16,759	(54,250)	113,429	(172,878)
Other Income, Net	3,581	2,358	22,458	6,410
(Loss) Income Before Income Taxes	(11,734)	46,440	226,414	90,591
Depreciation of property, plant and equipment	22,207	19,657	63,335	58,545
Pension Service Cost	8,490	5,557	25,306	16,581
Identifiable Assets	4,129,051		4,129,051		$ 4,127,829
Marketable equity securities	665,514		665,514		609,921
Investments in Affiliates	191,408		191,408		186,419
Prepaid Pension Cost	1,703,216		1,703,216		1,658,046
Total Assets	6,689,189		6,689,189		6,582,215
Amortization of Intangible Assets	11,759	14,635	39,007	44,436
Impairment of goodwill and other long-lived assets	98,321	0	99,066	0
Operating Segments [Member] | Education [Member]
Segment Reporting Information [Line Items]
Operating Revenues	411,837	355,064	1,192,105	1,066,089
Income (Loss) from Operations before Amortization of Intangible Assets and Impairment of Goodwill and Other Long-Lived Assets	33,069	22,625	94,625	69,952
Amortization of Intangible Assets and Impairment of Goodwill and Other Long-Lived Assets	3,210	3,980	11,610	12,190
Income (Loss) from Operations	29,859	18,645	83,015	57,762
Depreciation of property, plant and equipment	10,000	8,360	28,428	25,396
Pension Service Cost	2,226	2,233	6,680	6,700
Identifiable Assets	1,960,870		1,960,870		1,987,042
Amortization of Intangible Assets	3,210	3,980	11,133	12,190
Impairment of goodwill and other long-lived assets	0	0	477	0
Operating Segments [Member] | Education [Member] | Reportable Subsegments [Member] | Kaplan International [Member]
Segment Reporting Information [Line Items]
Operating Revenues	249,976	193,085	714,715	598,469
Income (Loss) from Operations before Amortization of Intangible Assets and Impairment of Goodwill and Other Long-Lived Assets	22,220	8,503	64,272	48,130
Income (Loss) from Operations	22,220	8,503	64,272	48,130
Depreciation of property, plant and equipment	7,599	5,709	20,832	17,258
Pension Service Cost	83	67	244	202
Identifiable Assets	1,437,590		1,437,590		1,479,833
Operating Segments [Member] | Education [Member] | Reportable Subsegments [Member] | Higher Education [Member]
Segment Reporting Information [Line Items]
Operating Revenues	81,925	82,314	250,557	233,990
Income (Loss) from Operations before Amortization of Intangible Assets and Impairment of Goodwill and Other Long-Lived Assets	8,465	9,064	33,343	17,423
Income (Loss) from Operations	8,465	9,064	33,343	17,423
Depreciation of property, plant and equipment	1,258	1,050	3,431	3,256
Pension Service Cost	958	961	2,803	2,862
Identifiable Assets	223,593		223,593		187,034
Operating Segments [Member] | Education [Member] | Reportable Subsegments [Member] | Supplemental Education [Member]
Segment Reporting Information [Line Items]
Operating Revenues	78,332	79,566	226,535	233,416
Income (Loss) from Operations before Amortization of Intangible Assets and Impairment of Goodwill and Other Long-Lived Assets	9,729	9,471	16,992	17,671
Income (Loss) from Operations	9,729	9,471	16,992	17,671
Depreciation of property, plant and equipment	1,117	1,570	4,087	4,787
Pension Service Cost	1,063	1,029	3,110	3,106
Identifiable Assets	252,571		252,571		268,499
Operating Segments [Member] | Education [Member] | Kaplan Corporate and Other [Member]
Segment Reporting Information [Line Items]
Operating Revenues	3,101	2,616	8,360	7,414
Income (Loss) from Operations before Amortization of Intangible Assets and Impairment of Goodwill and Other Long-Lived Assets	(7,412)	(4,616)	(20,074)	(13,438)
Income (Loss) from Operations	(10,622)	(8,596)	(31,684)	(25,628)
Depreciation of property, plant and equipment	26	31	78	95
Pension Service Cost	122	176	523	530
Identifiable Assets	47,116		47,116		51,676
Operating Segments [Member] | Education [Member] | Intersubsegment Eliminations [Member]
Segment Reporting Information [Line Items]
Operating Revenues	(1,497)	(2,517)	(8,062)	(7,200)
Income (Loss) from Operations before Amortization of Intangible Assets and Impairment of Goodwill and Other Long-Lived Assets	67	203	92	166
Income (Loss) from Operations	67	203	92	166
Operating Segments [Member] | Television Broadcasting [Member]
Segment Reporting Information [Line Items]
Operating Revenues	116,112	135,165	347,818	380,970
Income (Loss) from Operations before Amortization of Intangible Assets and Impairment of Goodwill and Other Long-Lived Assets	33,310	53,691	97,808	135,991
Amortization of Intangible Assets and Impairment of Goodwill and Other Long-Lived Assets	1,363	1,360	4,088	4,080
Income (Loss) from Operations	31,947	52,331	93,720	131,911
Depreciation of property, plant and equipment	3,120	2,961	9,243	9,335
Pension Service Cost	833	884	2,498	2,666
Identifiable Assets	420,938		420,938		431,084
Operating Segments [Member] | Manufacturing [Member]
Segment Reporting Information [Line Items]
Operating Revenues	109,216	122,964	343,882	365,966
Income (Loss) from Operations before Amortization of Intangible Assets and Impairment of Goodwill and Other Long-Lived Assets	10,515	14,723	39,019	39,527
Amortization of Intangible Assets and Impairment of Goodwill and Other Long-Lived Assets	51,489	5,076	60,683	15,403
Income (Loss) from Operations	(40,974)	9,647	(21,664)	24,124
Depreciation of property, plant and equipment	2,388	2,358	6,957	7,109
Pension Service Cost	280	276	836	828
Identifiable Assets	435,324		435,324		486,487
Operating Segments [Member] | Healthcare [Member]
Segment Reporting Information [Line Items]
Operating Revenues	116,164	87,176	331,505	230,816
Income (Loss) from Operations before Amortization of Intangible Assets and Impairment of Goodwill and Other Long-Lived Assets	6,837	6,953	19,986	21,491
Amortization of Intangible Assets and Impairment of Goodwill and Other Long-Lived Assets	866	905	2,702	2,822
Income (Loss) from Operations	5,971	6,048	17,284	18,669
Depreciation of property, plant and equipment	1,411	590	3,802	1,455
Pension Service Cost	3,521	138	10,563	417
Identifiable Assets	252,770		252,770		249,845
Operating Segments [Member] | Automotive [Member]
Segment Reporting Information [Line Items]
Operating Revenues	272,018	211,396	765,251	509,965
Income (Loss) from Operations before Amortization of Intangible Assets and Impairment of Goodwill and Other Long-Lived Assets	8,240	11,050	28,543	25,493
Amortization of Intangible Assets and Impairment of Goodwill and Other Long-Lived Assets	3	0	3	0
Income (Loss) from Operations	8,237	11,050	28,540	25,493
Depreciation of property, plant and equipment	1,304	1,067	3,565	2,596
Pension Service Cost	16	6	26	17
Identifiable Assets	568,673		568,673		427,221
Operating Segments [Member] | Other Businesses [Member]
Segment Reporting Information [Line Items]
Operating Revenues	86,653	101,207	269,110	308,150
Income (Loss) from Operations before Amortization of Intangible Assets and Impairment of Goodwill and Other Long-Lived Assets	(24,404)	(17,840)	(73,428)	(68,301)
Amortization of Intangible Assets and Impairment of Goodwill and Other Long-Lived Assets	53,149	3,314	58,987	9,941
Income (Loss) from Operations	(77,553)	(21,154)	(132,415)	(78,242)
Depreciation of property, plant and equipment	3,832	4,169	10,882	12,198
Pension Service Cost	662	552	1,847	1,549
Identifiable Assets	366,694		366,694		475,583
Corporate Office [Member]
Segment Reporting Information [Line Items]
Operating Revenues	365	0	1,215	0
Income (Loss) from Operations before Amortization of Intangible Assets and Impairment of Goodwill and Other Long-Lived Assets	(14,599)	(17,035)	(39,881)	(40,886)
Amortization of Intangible Assets and Impairment of Goodwill and Other Long-Lived Assets	0	0	0	0
Income (Loss) from Operations	(14,599)	(17,035)	(39,881)	(40,886)
Depreciation of property, plant and equipment	152	152	458	456
Pension Service Cost	952	1,468	2,856	4,404
Identifiable Assets	123,782		123,782		$ 70,567
Intersegment Elimination [Member]
Segment Reporting Information [Line Items]
Operating Revenues	$ (846)	$ (534)	$ (2,822)	$ (1,495)