Business Segments (Information by Operating Segment) (Details 1) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018	Dec. 31, 2018
Segment Reporting Information [Line Items]
Operating Revenues	$ 737,602	$ 672,677	$ 1,429,801	$ 1,332,113
Income (Loss) from Operations	57,963	65,626	97,966	109,840
Equity in earnings of affiliates, net	1,467	931	3,146	3,510
Interest Expense, Net	(6,807)	(15,264)	(12,532)	(21,963)
Debt Extinguishment Costs	0	(11,378)	0	(11,378)
Non-operating pension and postretirement benefit income, net	12,253	23,041	32,181	44,427
Gain (loss) on marketable equity securities, net	7,791	(2,554)	31,857	(16,656)
Other income, net	1,228	2,333	30,579	11,520
Income Before Income Taxes	73,895	62,735	183,197	119,300
Depreciation of property, plant and equipment	13,884	13,619	27,407	28,261
Amortization Of Intangible Assets and Impairment of Long-Lived Assets	13,573	11,399	26,633	21,783
Amortization of Intangible Assets	12,880	11,399	25,940	21,783
Impairment of long-lived assets	693	0	693	0
Pension Service Cost	4,963	4,317	10,184	9,257
Identifiable Assets	3,510,636		3,510,636		$ 3,120,280
Marketable equity securities	518,099		518,099		496,390
Investments in Affiliates	159,660		159,660		143,813
Prepaid Pension Cost	1,024,555		1,024,555		1,003,558
Total Assets	5,212,950		5,212,950		4,764,041
Operating Segments [Member] | Education [Member]
Segment Reporting Information [Line Items]
Operating Revenues	367,763	370,005	740,217	745,504
Income (Loss) from Operations	26,305	37,554	51,900	60,254
Depreciation of property, plant and equipment	6,137	6,839	12,338	14,445
Amortization Of Intangible Assets and Impairment of Long-Lived Assets	4,070	1,663	7,637	2,812
Amortization of Intangible Assets	3,377	1,663	6,944	2,812
Impairment of long-lived assets	693	0	693	0
Pension Service Cost	2,522	1,878	5,186	4,542
Identifiable Assets	1,789,059		1,789,059		1,568,747
Operating Segments [Member] | Education [Member] | Kaplan Corporate and Other [Member]
Segment Reporting Information [Line Items]
Operating Revenues	2,369	442	4,671	727
Income (Loss) from Operations	(10,990)	(8,763)	(22,394)	(17,658)
Depreciation of property, plant and equipment	54	158	106	312
Pension Service Cost	160	(29)	330	127
Identifiable Assets	61,373		61,373		28,731
Operating Segments [Member] | Education [Member] | Reportable Subsegments [Member] | Kaplan International [Member]
Segment Reporting Information [Line Items]
Operating Revenues	188,580	184,303	374,336	367,885
Income (Loss) from Operations	25,537	24,187	49,822	44,591
Depreciation of property, plant and equipment	3,716	3,764	7,598	7,738
Pension Service Cost	110	84	227	167
Identifiable Assets	1,225,819		1,225,819		1,101,040
Operating Segments [Member] | Education [Member] | Reportable Subsegments [Member] | Higher Education [Member]
Segment Reporting Information [Line Items]
Operating Revenues	76,288	85,981	159,068	185,811
Income (Loss) from Operations	2,721	11,219	4,636	12,574
Depreciation of property, plant and equipment	629	1,274	1,226	3,132
Pension Service Cost	1,102	804	2,265	2,210
Identifiable Assets	186,623		186,623		126,752
Operating Segments [Member] | Education [Member] | Reportable Subsegments [Member] | Test Preparation [Member]
Segment Reporting Information [Line Items]
Operating Revenues	65,673	68,604	126,823	127,755
Income (Loss) from Operations	4,289	6,120	3,835	6,641
Depreciation of property, plant and equipment	779	973	1,584	1,951
Pension Service Cost	821	729	1,687	1,458
Identifiable Assets	158,612		158,612		145,308
Operating Segments [Member] | Education [Member] | Reportable Subsegments [Member] | Professional (U.S.) [Member]
Segment Reporting Information [Line Items]
Operating Revenues	35,147	31,057	76,361	64,413
Income (Loss) from Operations	4,745	4,780	16,004	14,095
Depreciation of property, plant and equipment	959	670	1,824	1,312
Pension Service Cost	329	290	677	580
Identifiable Assets	156,632		156,632		166,916
Operating Segments [Member] | Education [Member] | Intersubsegment Eliminations [Member]
Segment Reporting Information [Line Items]
Operating Revenues	(294)	(382)	(1,042)	(1,087)
Income (Loss) from Operations	3	11	(3)	11
Operating Segments [Member] | Television Broadcasting [Member]
Segment Reporting Information [Line Items]
Operating Revenues	116,628	114,086	224,851	222,888
Income (Loss) from Operations	44,494	41,118	80,034	81,660
Depreciation of property, plant and equipment	3,293	2,974	6,532	6,045
Amortization Of Intangible Assets and Impairment of Long-Lived Assets	1,408	1,408	2,816	2,816
Pension Service Cost	780	601	1,511	1,094
Identifiable Assets	475,379		475,379		452,853
Operating Segments [Member] | Healthcare [Member]
Segment Reporting Information [Line Items]
Operating Revenues	40,641	38,208	78,369	75,829
Income (Loss) from Operations	2,598	764	4,927	(627)
Depreciation of property, plant and equipment	607	647	1,217	1,300
Amortization Of Intangible Assets and Impairment of Long-Lived Assets	1,410	1,809	2,808	3,617
Pension Service Cost	63	165	246	287
Identifiable Assets	123,876		123,876		108,596
Operating Segments [Member] | Other Businesses [Member]
Segment Reporting Information [Line Items]
Operating Revenues	212,614	150,399	386,448	287,937
Income (Loss) from Operations	(2,196)	(1,054)	(11,433)	(4,749)
Depreciation of property, plant and equipment	3,605	2,906	6,838	5,965
Amortization Of Intangible Assets and Impairment of Long-Lived Assets	6,685	6,519	13,372	12,538
Pension Service Cost	367	378	841	667
Identifiable Assets	962,227		962,227		827,113
Corporate Office [Member]
Segment Reporting Information [Line Items]
Operating Revenues	0	0	0	0
Income (Loss) from Operations	(13,238)	(12,756)	(27,462)	(26,698)
Depreciation of property, plant and equipment	242	253	482	506
Amortization Of Intangible Assets and Impairment of Long-Lived Assets	0	0	0	0
Pension Service Cost	1,231	1,295	2,400	2,667
Identifiable Assets	160,095		160,095		$ 162,971
Intersegment Elimination [Member]
Segment Reporting Information [Line Items]
Operating Revenues	$ (44)	$ (21)	$ (84)	$ (45)