Business Segments (Information by Operating Segment) (Details 1) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016	Dec. 31, 2016
Segment Reporting Information [Line Items]
Operating Revenues	$ 657,225	$ 621,638	$ 1,916,029	$ 1,852,311
Income (Loss) from Operations	44,571	68,033	141,986	194,045
Equity in earnings (losses) of affiliates, net	(532)	(1,008)	1,448	(895)
Interest Expense, Net	(7,758)	(7,874)	(22,386)	(22,481)
Other income (expense), net	1,963	(18,225)	6,881	15,871
Income Before Income Taxes	38,244	40,926	127,929	186,540
Depreciation of property, plant and equipment	16,002	16,097	46,525	48,903
Amortization of Intangible Assets	10,923	6,620	28,290	19,160
Amortization of Intangible Assets and Impairment of Goodwill and Other Long-Lived Assets	11,235	6,620	37,826	19,160
Net Pension (Credit) Expense	(13,832)	(12,389)	(43,349)	(36,714)
Identifiable Assets	3,139,052		3,139,052		$ 3,068,042
Investments in Marketable Equity Securities	495,599		495,599		424,229
Investments in Affiliates	122,166		122,166		58,806
Prepaid Pension Cost	863,098		863,098		881,593
Total Assets	4,619,915		4,619,915		4,432,670
Operating Segments [Member] | Education [Member]
Segment Reporting Information [Line Items]
Operating Revenues	376,805	386,936	1,136,201	1,207,225
Income (Loss) from Operations	13,391	16,333	55,347	63,713
Depreciation of property, plant and equipment	8,085	9,977	24,994	31,322
Amortization of Intangible Assets	1,355	1,773	3,798	5,158
Amortization of Intangible Assets and Impairment of Goodwill and Other Long-Lived Assets	1,355	1,773	3,798	5,158
Net Pension (Credit) Expense	2,430	2,838	7,289	8,965
Identifiable Assets	1,615,116		1,615,116		1,479,267
Operating Segments [Member] | Education [Member] | Kaplan Corporate and Other [Member]
Segment Reporting Information [Line Items]
Operating Revenues	49	47	120	190
Income (Loss) from Operations	(8,037)	(5,310)	(22,957)	(22,526)
Depreciation of property, plant and equipment	130	19	395	421
Net Pension (Credit) Expense	1,614	98	389	745
Identifiable Assets	19,322		19,322		21,509
Operating Segments [Member] | Education [Member] | Reportable Subsegments [Member] | Higher Education [Member]
Segment Reporting Information [Line Items]
Operating Revenues	133,459	148,602	416,973	472,131
Income (Loss) from Operations	8,809	11,494	39,124	50,037
Depreciation of property, plant and equipment	2,768	4,157	9,448	12,325
Net Pension (Credit) Expense	548	1,905	4,636	5,715
Identifiable Assets	349,756		349,756		373,127
Operating Segments [Member] | Education [Member] | Reportable Subsegments [Member] | Test Preparation [Member]
Segment Reporting Information [Line Items]
Operating Revenues	72,680	78,291	212,978	224,102
Income (Loss) from Operations	7,330	8,588	10,207	13,314
Depreciation of property, plant and equipment	1,407	1,441	4,080	4,837
Net Pension (Credit) Expense	244	768	2,066	2,304
Identifiable Assets	135,442		135,442		133,709
Operating Segments [Member] | Education [Member] | Reportable Subsegments [Member] | Kaplan International [Member]
Segment Reporting Information [Line Items]
Operating Revenues	171,259	160,456	507,568	512,068
Income (Loss) from Operations	5,348	1,561	29,009	22,937
Depreciation of property, plant and equipment	3,780	4,360	11,071	13,739
Net Pension (Credit) Expense	24	67	198	201
Identifiable Assets	1,110,596		1,110,596		950,922
Operating Segments [Member] | Education [Member] | Intersubsegment Eliminations [Member]
Segment Reporting Information [Line Items]
Operating Revenues	(642)	(460)	(1,438)	(1,266)
Income (Loss) from Operations	(59)	0	(36)	(49)
Operating Segments [Member] | Television Broadcasting [Member]
Segment Reporting Information [Line Items]
Operating Revenues	101,295	112,389	298,893	300,927
Income (Loss) from Operations	32,948	59,159	98,181	144,594
Depreciation of property, plant and equipment	3,118	2,540	8,703	7,367
Amortization of Intangible Assets and Impairment of Goodwill and Other Long-Lived Assets	1,071	63	2,943	189
Net Pension (Credit) Expense	485	428	1,457	1,285
Identifiable Assets	447,702		447,702		336,631
Operating Segments [Member] | Other Businesses [Member]
Segment Reporting Information [Line Items]
Operating Revenues	179,125	122,313	480,935	344,298
Income (Loss) from Operations	(7,033)	(10,801)	(26,515)	(21,593)
Depreciation of property, plant and equipment	4,520	3,289	11,968	9,389
Amortization of Intangible Assets and Impairment of Goodwill and Other Long-Lived Assets	8,809	4,784	31,085	13,813
Net Pension (Credit) Expense	1,375	279	2,273	839
Identifiable Assets	918,684		918,684		796,935
Corporate Office [Member]
Segment Reporting Information [Line Items]
Operating Revenues	0	0	0	0
Income (Loss) from Operations	5,265	3,342	14,973	7,331
Depreciation of property, plant and equipment	279	291	860	825
Amortization of Intangible Assets and Impairment of Goodwill and Other Long-Lived Assets	0	0	0	0
Net Pension (Credit) Expense	(18,122)	(15,934)	(54,368)	(47,803)
Identifiable Assets	157,550		157,550		$ 455,209
Intersegment Elimination [Member]
Segment Reporting Information [Line Items]
Operating Revenues	$ 0	$ 0	$ 0	$ (139)