Business Segments (Information by Operating Segment) (Details 1) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017	Dec. 31, 2017
Segment Reporting Information [Line Items]
Operating Revenues	$ 672,677	$ 676,087	$ 1,332,113	$ 1,258,804
Income (Loss) from Operations	65,626	49,741	109,840	59,994
Equity in earnings (losses) of affiliates, net	931	1,331	3,510	1,980
Interest Expense, Net	(15,264)	(7,862)	(21,963)	(14,628)
Debt Extinguishment Costs	(11,378)	0	(11,378)	0
Non-operating pension and postretirement benefit income, net	23,041	18,620	44,427	37,421
Loss on marketable equity securities, net	(2,554)	0	(16,656)	0
Other income, net	2,333	4,069	11,520	4,918
Income Before Income Taxes	62,735	65,899	119,300	89,685
Depreciation of property, plant and equipment	13,619	15,871	28,261	30,523
Amortization of Intangible Assets	11,399	10,531	21,783	17,367
Amortization of Intangible Assets and Impairment of Goodwill and Other Long-Lived Assets	11,399	19,755	21,783	26,591
Pension Expense	4,317	4,591	9,257	9,505
Identifiable Assets	3,053,957		3,053,957		$ 3,216,141
Marketable equity securities	452,917		452,917
Marketable Equity Securities					536,315
Investments in Affiliates	133,550		133,550		128,590
Prepaid Pension Cost	1,090,509		1,090,509		1,056,777
Total Assets	4,730,933		4,730,933		4,937,823
Operating Segments [Member] | Education [Member]
Segment Reporting Information [Line Items]
Operating Revenues	370,005	386,499	745,504	759,396
Income (Loss) from Operations	37,554	33,331	60,254	42,768
Depreciation of property, plant and equipment	6,839	8,325	14,445	16,909
Amortization of Intangible Assets	1,663	1,323	2,812	2,443
Amortization of Intangible Assets and Impairment of Goodwill and Other Long-Lived Assets	1,663	1,323	2,812	2,443
Pension Expense	1,878	2,153	4,542	4,859
Identifiable Assets	1,543,166		1,543,166		1,592,097
Operating Segments [Member] | Education [Member] | Kaplan Corporate and Other [Member]
Segment Reporting Information [Line Items]
Operating Revenues	442	57	727	71
Income (Loss) from Operations	(8,763)	(6,045)	(17,658)	(14,108)
Depreciation of property, plant and equipment	158	135	312	265
Pension Expense	(29)	(889)	127	(1,225)
Identifiable Assets	15,326		15,326		21,624
Operating Segments [Member] | Education [Member] | Reportable Subsegments [Member] | Kaplan International [Member]
Segment Reporting Information [Line Items]
Operating Revenues	184,303	171,747	367,885	336,309
Income (Loss) from Operations	24,187	15,954	44,591	23,661
Depreciation of property, plant and equipment	3,764	3,609	7,738	7,291
Pension Expense	84	87	167	174
Identifiable Assets	1,049,790		1,049,790		1,115,919
Operating Segments [Member] | Education [Member] | Reportable Subsegments [Member] | Higher Education [Member]
Segment Reporting Information [Line Items]
Operating Revenues	85,981	111,840	185,811	222,951
Income (Loss) from Operations	11,219	13,140	12,574	15,586
Depreciation of property, plant and equipment	1,274	2,484	3,132	5,132
Pension Expense	804	1,742	2,210	3,484
Identifiable Assets	224,272		224,272		231,986
Operating Segments [Member] | Education [Member] | Reportable Subsegments [Member] | Test Preparation [Member]
Segment Reporting Information [Line Items]
Operating Revenues	68,604	75,730	127,755	140,298
Income (Loss) from Operations	6,120	5,741	6,641	2,877
Depreciation of property, plant and equipment	973	1,332	1,951	2,673
Pension Expense	729	911	1,458	1,822
Identifiable Assets	132,067		132,067		130,938
Operating Segments [Member] | Education [Member] | Reportable Subsegments [Member] | Professional (U.S.) [Member]
Segment Reporting Information [Line Items]
Operating Revenues	31,057	27,364	64,413	60,563
Income (Loss) from Operations	4,780	4,571	14,095	14,729
Depreciation of property, plant and equipment	670	765	1,312	1,548
Pension Expense	290	302	580	604
Identifiable Assets	121,711		121,711		91,630
Operating Segments [Member] | Education [Member] | Intersubsegment Eliminations [Member]
Segment Reporting Information [Line Items]
Operating Revenues	(382)	(239)	(1,087)	(796)
Income (Loss) from Operations	11	(30)	11	23
Operating Segments [Member] | Television Broadcasting [Member]
Segment Reporting Information [Line Items]
Operating Revenues	114,086	106,102	222,888	197,598
Income (Loss) from Operations	41,118	39,777	81,660	66,260
Depreciation of property, plant and equipment	2,974	2,991	6,045	5,585
Amortization of Intangible Assets and Impairment of Goodwill and Other Long-Lived Assets	1,408	970	2,816	1,872
Pension Expense	601	479	1,094	972
Identifiable Assets	454,180		454,180		455,884
Operating Segments [Member] | Healthcare [Member]
Segment Reporting Information [Line Items]
Operating Revenues	38,208	38,220	75,829	75,119
Income (Loss) from Operations	764	384	(627)	(542)
Depreciation of property, plant and equipment	647	1,194	1,300	2,263
Amortization of Intangible Assets and Impairment of Goodwill and Other Long-Lived Assets	1,809	1,644	3,617	3,298
Pension Expense	165	166	287	332
Identifiable Assets	119,231		119,231		129,856
Operating Segments [Member] | Other Businesses [Member]
Segment Reporting Information [Line Items]
Operating Revenues	150,399	145,266	287,937	226,691
Income (Loss) from Operations	(1,054)	(9,302)	(4,749)	(18,940)
Depreciation of property, plant and equipment	2,906	3,070	5,965	5,185
Amortization of Intangible Assets and Impairment of Goodwill and Other Long-Lived Assets	6,519	15,818	12,538	18,978
Pension Expense	378	249	667	566
Identifiable Assets	790,735		790,735		855,399
Corporate Office [Member]
Segment Reporting Information [Line Items]
Operating Revenues	0	0	0	0
Income (Loss) from Operations	(12,756)	(14,449)	(26,698)	(29,552)
Depreciation of property, plant and equipment	253	291	506	581
Amortization of Intangible Assets and Impairment of Goodwill and Other Long-Lived Assets	0	0	0	0
Pension Expense	1,295	1,544	2,667	2,776
Identifiable Assets	146,645		146,645		$ 182,905
Intersegment Elimination [Member]
Segment Reporting Information [Line Items]
Operating Revenues	$ (21)	$ 0	$ (45)	$ 0