Business Segments (Information by Operating Segment) (Details 1) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018	Dec. 31, 2018
Segment Reporting Information [Line Items]
Operating Revenues	$ 692,199	$ 659,436
Income (Loss) from Operations	40,003	44,214
Equity in earnings of affiliates, net	1,679	2,579
Interest Expense, Net	(5,725)	(6,699)
Non-operating pension and postretirement benefit income, net	19,928	21,386
Gain (loss) on marketable equity securities, net	24,066	(14,102)
Other income, net	29,351	9,187
Income Before Income Taxes	109,302	56,565
Depreciation of property, plant and equipment	13,523	14,642
Amortization of Intangible Assets	13,060	10,384
Pension Expense	5,221	4,940
Identifiable Assets	3,529,216		$ 3,120,280
Marketable equity securities	510,307		496,390
Investments in Affiliates	140,127		143,813
Prepaid Pension Cost	1,017,584		1,003,558
Total Assets	5,197,234		4,764,041
Operating Segments [Member] | Education [Member]
Segment Reporting Information [Line Items]
Operating Revenues	372,454	375,499
Income (Loss) from Operations	25,595	22,700
Depreciation of property, plant and equipment	6,201	7,606
Amortization of Intangible Assets	3,567	1,149
Pension Expense	2,664	2,664
Identifiable Assets	1,853,208		1,568,747
Operating Segments [Member] | Education [Member] | Kaplan Corporate and Other [Member]
Segment Reporting Information [Line Items]
Operating Revenues	2,302	285
Income (Loss) from Operations	(11,404)	(8,895)
Depreciation of property, plant and equipment	52	154
Pension Expense	170	156
Identifiable Assets	67,204		28,731
Operating Segments [Member] | Education [Member] | Reportable Subsegments [Member] | Kaplan International [Member]
Segment Reporting Information [Line Items]
Operating Revenues	185,756	183,582
Income (Loss) from Operations	24,285	20,404
Depreciation of property, plant and equipment	3,882	3,974
Pension Expense	117	83
Identifiable Assets	1,273,080		1,101,040
Operating Segments [Member] | Education [Member] | Reportable Subsegments [Member] | Higher Education [Member]
Segment Reporting Information [Line Items]
Operating Revenues	82,780	99,830
Income (Loss) from Operations	1,915	1,355
Depreciation of property, plant and equipment	597	1,858
Pension Expense	1,163	1,406
Identifiable Assets	182,909		126,752
Operating Segments [Member] | Education [Member] | Reportable Subsegments [Member] | Test Preparation [Member]
Segment Reporting Information [Line Items]
Operating Revenues	61,150	59,151
Income (Loss) from Operations	(454)	521
Depreciation of property, plant and equipment	805	978
Pension Expense	866	729
Identifiable Assets	159,620		145,308
Operating Segments [Member] | Education [Member] | Reportable Subsegments [Member] | Professional (U.S.) [Member]
Segment Reporting Information [Line Items]
Operating Revenues	41,214	33,356
Income (Loss) from Operations	11,259	9,315
Depreciation of property, plant and equipment	865	642
Pension Expense	348	290
Identifiable Assets	170,395		166,916
Operating Segments [Member] | Education [Member] | Intersubsegment Eliminations [Member]
Segment Reporting Information [Line Items]
Operating Revenues	(748)	(705)
Income (Loss) from Operations	(6)	0
Operating Segments [Member] | Television Broadcasting [Member]
Segment Reporting Information [Line Items]
Operating Revenues	108,223	108,802
Income (Loss) from Operations	35,540	40,542
Depreciation of property, plant and equipment	3,239	3,071
Amortization of Intangible Assets	1,408	1,408
Pension Expense	731	493
Identifiable Assets	467,270		452,853
Operating Segments [Member] | Healthcare [Member]
Segment Reporting Information [Line Items]
Operating Revenues	37,728	37,621
Income (Loss) from Operations	2,329	(1,391)
Depreciation of property, plant and equipment	610	653
Amortization of Intangible Assets	1,398	1,808
Pension Expense	183	122
Identifiable Assets	115,622		108,596
Operating Segments [Member] | Other Businesses [Member]
Segment Reporting Information [Line Items]
Operating Revenues	173,834	137,538
Income (Loss) from Operations	(9,237)	(3,695)
Depreciation of property, plant and equipment	3,233	3,059
Amortization of Intangible Assets	6,687	6,019
Pension Expense	474	289
Identifiable Assets	951,773		827,113
Corporate Office [Member]
Segment Reporting Information [Line Items]
Operating Revenues	0	0
Income (Loss) from Operations	(14,224)	(13,942)
Depreciation of property, plant and equipment	240	253
Amortization of Intangible Assets	0	0
Pension Expense	1,169	1,372
Identifiable Assets	141,343		$ 162,971
Intersegment Elimination [Member]
Segment Reporting Information [Line Items]
Operating Revenues	$ (40)	$ (24)