Business Segments (Information by Operating Segment) (Details 1) - USD ($) $ in Thousands	3 Months Ended			9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Jun. 30, 2017	Sep. 30, 2018	Sep. 30, 2017	Dec. 31, 2017
Segment Reporting Information [Line Items]
Operating Revenues	$ 674,766	$ 657,225		$ 2,006,879	$ 1,916,029
Income (Loss) from Operations	60,739	26,950		170,579	86,944
Equity in earnings (losses) of affiliates, net	9,537	(532)		13,047	1,448
Interest Expense, Net	(5,524)	(7,758)		(27,487)	(22,386)
Debt Extinguishment Costs	0	0		(11,378)	0
Non-operating pension and postretirement benefit income, net	22,214	17,621		66,641	55,042
Gain on marketable equity securities, net	44,962	0		28,306	0
Other income, net	3,142	1,963		14,662	6,881
Income Before Income Taxes	135,070	38,244		254,370	127,929
Depreciation of property, plant and equipment	13,648	16,002		41,909	46,525
Amortization of Intangible Assets	12,269	10,923		34,052	28,290
Amortization of Intangible Assets and Impairment of Goodwill and Other Long-Lived Assets	20,378	11,235		42,161	37,826
Pension Expense	4,473	4,591		13,730	14,096
Identifiable Assets	3,126,946			3,126,946		$ 3,216,141
Marketable equity securities	497,879			497,879
Marketable Equity Securities						536,315
Investments in Affiliates	142,756			142,756		128,590
Prepaid Pension Cost	1,106,162			1,106,162		1,056,777
Total Assets	4,873,743			4,873,743		4,937,823
Goodwill and other long-lived asset impairment charge	8,109	312	$ 9,200	8,109	9,536
Operating Segments [Member] | Education [Member]
Segment Reporting Information [Line Items]
Operating Revenues	358,601	376,805		1,104,105	1,136,201
Income (Loss) from Operations	22,262	13,797		82,516	56,565
Depreciation of property, plant and equipment	6,685	8,085		21,130	24,994
Amortization of Intangible Assets	2,682	1,355		5,494	3,798
Amortization of Intangible Assets and Impairment of Goodwill and Other Long-Lived Assets	2,682	1,355		5,494	3,798
Pension Expense	2,107	2,430		6,649	7,289
Identifiable Assets	1,599,680			1,599,680		1,592,097
Operating Segments [Member] | Education [Member] | Kaplan Corporate and Other [Member]
Segment Reporting Information [Line Items]
Operating Revenues	143	49		870	120
Income (Loss) from Operations	(9,452)	(7,631)		(27,110)	(21,739)
Depreciation of property, plant and equipment	119	130		431	395
Pension Expense	123	1,614		250	389
Identifiable Assets	29,970			29,970		21,624
Operating Segments [Member] | Education [Member] | Reportable Subsegments [Member] | Kaplan International [Member]
Segment Reporting Information [Line Items]
Operating Revenues	167,668	171,259		535,553	507,568
Income (Loss) from Operations	8,375	5,348		52,966	29,009
Depreciation of property, plant and equipment	3,759	3,780		11,497	11,071
Pension Expense	66	24		233	198
Identifiable Assets	1,109,470			1,109,470		1,115,919
Operating Segments [Member] | Education [Member] | Reportable Subsegments [Member] | Higher Education [Member]
Segment Reporting Information [Line Items]
Operating Revenues	89,269	105,210		275,080	328,161
Income (Loss) from Operations	6,042	1,493		18,616	17,079
Depreciation of property, plant and equipment	915	2,010		4,047	7,142
Pension Expense	1,050	467		3,260	3,951
Identifiable Assets	144,274			144,274		231,986
Operating Segments [Member] | Education [Member] | Reportable Subsegments [Member] | Test Preparation [Member]
Segment Reporting Information [Line Items]
Operating Revenues	67,749	72,680		195,504	212,978
Income (Loss) from Operations	10,572	7,330		17,213	10,207
Depreciation of property, plant and equipment	1,033	1,407		2,984	4,080
Pension Expense	577	244		2,035	2,066
Identifiable Assets	155,846			155,846		130,938
Operating Segments [Member] | Education [Member] | Reportable Subsegments [Member] | Professional (U.S.) [Member]
Segment Reporting Information [Line Items]
Operating Revenues	34,302	28,249		98,715	88,812
Income (Loss) from Operations	6,768	7,316		20,863	22,045
Depreciation of property, plant and equipment	859	758		2,171	2,306
Pension Expense	291	81		871	685
Identifiable Assets	160,120			160,120		91,630
Operating Segments [Member] | Education [Member] | Intersubsegment Eliminations [Member]
Segment Reporting Information [Line Items]
Operating Revenues	(530)	(642)		(1,617)	(1,438)
Income (Loss) from Operations	(43)	(59)		(32)	(36)
Operating Segments [Member] | Television Broadcasting [Member]
Segment Reporting Information [Line Items]
Operating Revenues	130,014	101,295		352,902	298,893
Income (Loss) from Operations	55,453	33,462		137,113	99,722
Depreciation of property, plant and equipment	3,198	3,118		9,243	8,703
Amortization of Intangible Assets and Impairment of Goodwill and Other Long-Lived Assets	1,408	1,071		4,224	2,943
Pension Expense	544	485		1,638	1,457
Identifiable Assets	455,746			455,746		455,884
Operating Segments [Member] | Healthcare [Member]
Segment Reporting Information [Line Items]
Operating Revenues	35,486	40,473		111,315	115,592
Income (Loss) from Operations	(8,702)	920		(9,329)	378
Depreciation of property, plant and equipment	648	1,166		1,948	3,429
Amortization of Intangible Assets and Impairment of Goodwill and Other Long-Lived Assets	9,839	2,420		13,456	5,718
Pension Expense	143	166		430	498
Identifiable Assets	108,685			108,685		129,856
Operating Segments [Member] | Other Businesses [Member]
Segment Reporting Information [Line Items]
Operating Revenues	150,665	138,652		438,602	365,343
Income (Loss) from Operations	4,613	(7,021)		(136)	(25,961)
Depreciation of property, plant and equipment	2,865	3,354		8,830	8,539
Amortization of Intangible Assets and Impairment of Goodwill and Other Long-Lived Assets	6,449	6,389		18,987	25,367
Pension Expense	346	277		1,013	843
Identifiable Assets	819,419			819,419		855,399
Corporate Office [Member]
Segment Reporting Information [Line Items]
Operating Revenues	0	0		0	0
Income (Loss) from Operations	(12,887)	(14,208)		(39,585)	(43,760)
Depreciation of property, plant and equipment	252	279		758	860
Amortization of Intangible Assets and Impairment of Goodwill and Other Long-Lived Assets	0	0		0	0
Pension Expense	1,333	1,233		4,000	4,009
Identifiable Assets	143,416			143,416		$ 182,905
Intersegment Elimination [Member]
Segment Reporting Information [Line Items]
Operating Revenues	$ 0	$ 0		$ (45)	$ 0