Business Segments (Information by Operating Segment) (Details 2) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019	Dec. 31, 2019
Segment Reporting Information [Line Items]
Operating Revenues	$ 652,871	$ 737,602	$ 1,385,128	$ 1,429,801
Income (Loss) from Operations	5,877	57,963	13,962	97,966
Equity in earnings (losses) of affiliates, net	1,182	1,467	(365)	3,146
Interest Expense, Net	(6,423)	(6,807)	(12,950)	(12,532)
Non-operating pension and postretirement benefit income, net	12,136	12,253	30,539	32,181
Gain (loss) on marketable equity securities, net	39,890	7,791	(60,503)	31,857
Other income, net	8,100	1,228	10,788	30,579
Income (Loss) Before Income Taxes	60,762	73,895	(18,529)	183,197
Depreciation of property, plant and equipment	22,913	13,884	39,617	27,407
Amortization of Intangible Assets and Impairment of Goodwill and Other Long-lived Assets	25,838	13,573	56,404	26,633
Amortization of Intangible Assets	14,327	12,880	28,492	25,940
Impairment of goodwill and other long-lived assets	11,511	693	27,912	693
Pension Service Cost	5,804	4,963	11,587	10,184
Identifiable Assets	3,768,658		3,768,658		$ 3,891,557
Marketable equity securities	431,808		431,808		585,080
Investments in Affiliates	156,677		156,677		162,249
Prepaid Pension Cost	1,315,174		1,315,174		1,292,350
Total Assets	5,672,317		5,672,317		5,931,236
Operating Segments [Member] | Education [Member]
Segment Reporting Information [Line Items]
Operating Revenues	333,175	367,763	689,553	740,217
Income (Loss) from Operations	12,254	26,305	16,946	51,900
Depreciation of property, plant and equipment	10,324	6,137	17,653	12,338
Amortization of Intangible Assets and Impairment of Goodwill and Other Long-lived Assets	14,291	4,070	18,492	7,637
Amortization of Intangible Assets	4,271	3,377	8,472	6,944
Impairment of goodwill and other long-lived assets	10,020	693	10,020	693
Pension Service Cost	2,592	2,522	5,177	5,186
Identifiable Assets	1,827,258		1,827,258		2,032,425
Operating Segments [Member] | Education [Member] | Kaplan Corporate and Other [Member]
Segment Reporting Information [Line Items]
Operating Revenues	3,039	2,369	6,244	4,671
Income (Loss) from Operations	(21,161)	(10,990)	(26,884)	(22,394)
Depreciation of property, plant and equipment	101	54	190	106
Pension Service Cost	318	160	636	330
Identifiable Assets	65,144		65,144		68,088
Operating Segments [Member] | Education [Member] | Reportable Subsegments [Member] | Kaplan International [Member]
Segment Reporting Information [Line Items]
Operating Revenues	164,713	188,580	364,328	374,336
Income (Loss) from Operations	16,035	25,537	35,015	49,822
Depreciation of property, plant and equipment	5,619	3,716	10,197	7,598
Pension Service Cost	120	110	232	227
Identifiable Assets	1,266,671		1,266,671		1,455,122
Operating Segments [Member] | Education [Member] | Reportable Subsegments [Member] | Higher Education [Member]
Segment Reporting Information [Line Items]
Operating Revenues	86,453	76,288	159,990	159,068
Income (Loss) from Operations	17,050	2,721	15,030	4,636
Depreciation of property, plant and equipment	832	629	1,555	1,226
Pension Service Cost	1,070	1,102	2,140	2,265
Identifiable Assets	210,789		210,789		196,761
Operating Segments [Member] | Education [Member] | Reportable Subsegments [Member] | Test Preparation [Member]
Segment Reporting Information [Line Items]
Operating Revenues	51,111	65,673	93,950	126,823
Income (Loss) from Operations	(1,048)	4,289	(13,724)	3,835
Depreciation of property, plant and equipment	2,607	779	3,433	1,584
Pension Service Cost	823	821	1,646	1,687
Identifiable Assets	138,359		138,359		151,655
Operating Segments [Member] | Education [Member] | Reportable Subsegments [Member] | Professional (U.S.) [Member]
Segment Reporting Information [Line Items]
Operating Revenues	28,674	35,147	67,123	76,361
Income (Loss) from Operations	1,378	4,745	7,504	16,004
Depreciation of property, plant and equipment	1,165	959	2,278	1,824
Pension Service Cost	261	329	523	677
Identifiable Assets	146,295		146,295		160,799
Operating Segments [Member] | Education [Member] | Intersubsegment Eliminations [Member]
Segment Reporting Information [Line Items]
Operating Revenues	(815)	(294)	(2,082)	(1,042)
Income (Loss) from Operations	0	3	5	(3)
Operating Segments [Member] | Television Broadcasting [Member]
Segment Reporting Information [Line Items]
Operating Revenues	100,762	116,628	216,210	224,851
Income (Loss) from Operations	23,627	44,494	59,403	80,034
Depreciation of property, plant and equipment	3,446	3,293	6,789	6,532
Amortization of Intangible Assets and Impairment of Goodwill and Other Long-lived Assets	1,361	1,408	2,721	2,816
Pension Service Cost	836	780	1,632	1,511
Identifiable Assets	450,134		450,134		463,689
Operating Segments [Member] | Manufacturing [Member]
Segment Reporting Information [Line Items]
Operating Revenues	83,239	114,873	196,697	230,030
Income (Loss) from Operations	(1,482)	4,692	5,019	7,966
Depreciation of property, plant and equipment	2,526	2,384	5,053	4,817
Amortization of Intangible Assets and Impairment of Goodwill and Other Long-lived Assets	6,988	6,528	14,125	13,058
Pension Service Cost	395	15	789	40
Identifiable Assets	557,767		557,767		564,251
Operating Segments [Member] | Healthcare [Member]
Segment Reporting Information [Line Items]
Operating Revenues	49,181	40,641	95,175	78,369
Income (Loss) from Operations	8,818	2,598	11,987	4,927
Depreciation of property, plant and equipment	493	607	1,033	1,217
Amortization of Intangible Assets and Impairment of Goodwill and Other Long-lived Assets	1,307	1,410	2,617	2,808
Pension Service Cost	112	63	271	246
Identifiable Assets	159,045		159,045		160,033
Operating Segments [Member] | SocialCode [Member]
Segment Reporting Information [Line Items]
Operating Revenues	10,483	16,382	22,506	29,829
Income (Loss) from Operations	(3,004)	(975)	(6,793)	(4,993)
Depreciation of property, plant and equipment	121	384	242	536
Amortization of Intangible Assets and Impairment of Goodwill and Other Long-lived Assets	1,647	157	1,804	314
Pension Service Cost	162	191	399	439
Identifiable Assets	122,421		122,421		221,746
Operating Segments [Member] | Other Businesses [Member]
Segment Reporting Information [Line Items]
Operating Revenues	76,380	81,359	165,648	126,589
Income (Loss) from Operations	(21,316)	(5,913)	(51,008)	(14,406)
Depreciation of property, plant and equipment	5,827	837	8,496	1,485
Amortization of Intangible Assets and Impairment of Goodwill and Other Long-lived Assets	244	0	16,645	0
Pension Service Cost	241	161	467	362
Identifiable Assets	391,031		391,031		345,649
Corporate Office [Member]
Segment Reporting Information [Line Items]
Operating Revenues	0	0	0	0
Income (Loss) from Operations	(13,020)	(13,238)	(21,592)	(27,462)
Depreciation of property, plant and equipment	176	242	351	482
Amortization of Intangible Assets and Impairment of Goodwill and Other Long-lived Assets	0	0	0	0
Pension Service Cost	1,466	1,231	2,852	2,400
Identifiable Assets	261,002		261,002		$ 103,764
Intersegment Elimination [Member]
Segment Reporting Information [Line Items]
Operating Revenues	$ (349)	$ (44)	$ (661)	$ (84)