Business Segments (Information by Operating Segment) (Details 2) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Segment Reporting Information [Line Items]
Operating Revenues	$ 675,817	$ 657,225	$ 676,087	$ 582,717	$ 629,579	$ 621,638	$ 628,933	$ 601,740	$ 2,591,846	$ 2,481,890	$ 2,586,114
Income (loss) from operations	67,116	44,571	68,361	29,054	109,489	68,033	74,140	51,872	209,102	303,534	(80,825)
Equity in losses of affiliates, net	(4,697)	(532)	1,331	649	(7,042)	(1,008)	(891)	1,004	(3,249)	(7,937)	(697)
Interest expense, net									(27,305)	(32,297)	(30,745)
Other income (expense), net	(2,640)	1,963	4,069	849	(28,513)	(18,225)	19,000	15,096	4,241	(12,642)	(8,623)
Income (Loss) from Continuing Operations Before Income Taxes	54,860	38,244	65,899	23,786	64,118	40,926	84,999	60,615	182,789	250,658	(120,890)
Depreciation of property, plant and equipment	15,984	16,002	15,871	14,652	15,717	16,097	16,045	16,761	62,509	64,620	77,906
Amortization of Intangible Assets	12,897	$ 10,923	$ 10,531	$ 6,836	7,511	$ 6,620	$ 6,278	$ 6,262	41,187	26,671	19,017
Amortization of intangible assets and impairment of goodwill and other long-lived assets									50,801	28,274	278,717
Net Pension (Credit) Expense									(57,214)	(67,097)	(60,557)
Capital expenditures									57,080	70,712	62,033
Identifiable Assets	3,216,141				3,068,042				3,216,141	3,068,042
Investments in Marketable equity securities	536,315				424,229				536,315	424,229
Investments in Affiliates	128,590				58,806				128,590	58,806
Prepaid Pension Cost	1,056,777				881,593				1,056,777	881,593
Total Assets	4,937,823				4,432,670				4,937,823	4,432,670
Operating Segments [Member] | Education [Member]
Segment Reporting Information [Line Items]
Operating Revenues									1,516,776	1,598,461	1,927,521
Income (loss) from operations									75,169	93,632	(223,456)
Depreciation of property, plant and equipment									32,906	41,187	61,177
Amortization of Intangible Assets									5,162	7,516	5,523
Amortization of intangible assets and impairment of goodwill and other long-lived assets									5,162	7,516	262,353
Impairment of goodwill and other long-lived assets									0	0	256,830
Net Pension (Credit) Expense									10,613	11,803	18,804
Capital expenditures									27,520	26,497	42,220
Identifiable Assets	1,592,097				1,479,267				1,592,097	1,479,267
Operating Segments [Member] | Education [Member] | Reportable Subsegments [Member] | Higher Education [Member]
Segment Reporting Information [Line Items]
Operating Revenues									547,264	617,047	849,625
Income (loss) from operations									44,277	66,632	55,572
Depreciation of property, plant and equipment									12,158	16,822	17,937
Net Pension (Credit) Expense									6,182	7,620	10,849
Capital expenditures									4,633	5,364	10,202
Identifiable Assets	323,616				373,127				323,616	373,127
Operating Segments [Member] | Education [Member] | Reportable Subsegments [Member] | Test Preparation [Member]
Segment Reporting Information [Line Items]
Operating Revenues									273,298	286,556	301,607
Income (loss) from operations									11,507	9,599	16,798
Depreciation of property, plant and equipment									5,286	6,287	9,045
Net Pension (Credit) Expense									2,755	3,072	3,101
Capital expenditures									1,038	4,672	8,720
Identifiable Assets	130,938				133,709				130,938	133,709
Operating Segments [Member] | Education [Member] | Reportable Subsegments [Member] | Kaplan International [Member]
Segment Reporting Information [Line Items]
Operating Revenues									697,999	696,362	770,273
Income (loss) from operations									50,730	48,398	53,661
Depreciation of property, plant and equipment									14,892	17,523	17,811
Net Pension (Credit) Expense									1,157	268	424
Capital expenditures									21,667	16,252	22,673
Identifiable Assets	1,115,919				950,922				1,115,919	950,922
Operating Segments [Member] | Education [Member] | Kaplan Corporate and Other [Member]
Segment Reporting Information [Line Items]
Operating Revenues									294	214	6,502
Income (loss) from operations									(31,488)	(30,968)	(349,583)
Depreciation of property, plant and equipment									570	555	16,384
Net Pension (Credit) Expense									519	843	4,430
Capital expenditures									182	209	625
Identifiable Assets	21,624				21,509				21,624	21,509
Operating Segments [Member] | Education [Member] | Intersubsegment Eliminations [Member]
Segment Reporting Information [Line Items]
Operating Revenues									(2,079)	(1,718)	(486)
Income (loss) from operations									143	(29)	96
Operating Segments [Member] | Television Broadcasting [Member]
Segment Reporting Information [Line Items]
Operating Revenues									409,916	409,718	359,192
Income (loss) from operations									137,203	200,470	164,927
Depreciation of property, plant and equipment									12,179	9,942	9,551
Amortization of intangible assets and impairment of goodwill and other long-lived assets									6,349	251	252
Net Pension (Credit) Expense									1,942	1,714	1,620
Capital expenditures									16,802	27,453	9,998
Identifiable Assets	455,884				336,631				455,884	336,631
Operating Segments [Member] | Other Segments [Member]
Segment Reporting Information [Line Items]
Operating Revenues									665,205	473,850	299,517
Income (loss) from operations									(22,764)	(22,102)	(13,667)
Depreciation of property, plant and equipment									16,306	12,375	6,168
Amortization of intangible assets and impairment of goodwill and other long-lived assets									39,290	20,507	16,112
Net Pension (Credit) Expense									2,722	1,118	964
Capital expenditures									12,758	16,047	9,504
Identifiable Assets	985,255				796,935				985,255	796,935
Corporate office [Member]
Segment Reporting Information [Line Items]
Operating Revenues									0	0	0
Income (loss) from operations									19,494	31,534	(8,629)
Depreciation of property, plant and equipment									1,118	1,116	1,010
Amortization of intangible assets and impairment of goodwill and other long-lived assets									0	0	0
Net Pension (Credit) Expense									(72,491)	(81,732)	(81,945)
Capital expenditures									0	715	311
Identifiable Assets	$ 182,905				$ 455,209				182,905	455,209
Intersegment Elimination [Member]
Segment Reporting Information [Line Items]
Operating Revenues									$ (51)	$ (139)	$ (116)