Intangible Assets, Net And Goodwill (Schedule Of Intangible Assets, Net And Goodwill) (Details) - USD ($) $ in Thousands	Sep. 30, 2016	Dec. 31, 2015
Intangible Assets [Line Items]
Intangible assets, net (excluding goodwill)	$ 864,554	$ 912,021
Goodwill	1,729,775	1,736,341
Total Intangible assets, net and goodwill	2,594,329	2,648,362
Exchange And Clearing Organization Membership Interests And Registrations [Member]
Intangible Assets [Line Items]
Indefinite lived intangibles	9,197	11,897
Customer And Other Relationships [Member]
Intangible Assets [Line Items]
Intangible assets, net (excluding goodwill)	430,579	456,222
Intangibles, accumulated amortization	217,418	191,761
Trademarks And Tradename [Member]
Intangible Assets [Line Items]
Intangible assets, net (excluding goodwill)	315,359	330,172
Intangibles, accumulated amortization	76,431	64,052
Supply Contracts [Member]
Intangible Assets [Line Items]
Intangible assets, net (excluding goodwill)	101,769	109,311
Intangibles, accumulated amortization	48,226	40,684
Other Intangible Assets [Member]
Intangible Assets [Line Items]
Intangible assets, net (excluding goodwill)	7,650	4,419
Intangibles, accumulated amortization	5,985	5,216
National Beef [Member]
Intangible Assets [Line Items]
Goodwill	14,991	14,991
Jefferies [Member]
Intangible Assets [Line Items]
Goodwill	1,701,504	1,712,799
Other Operations [Member]
Intangible Assets [Line Items]
Goodwill	$ 13,280	$ 8,551