Long-Term Debt (Schedule Of Debt) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Debt Instrument [Line Items]
Long-term debt	$ 7,380,443	$ 7,400,582
Long-term debt, fair value	248,856
Debt matures in 2018	1,172,200
Debt maturities in 2019	958,400
Subsidiary [Member]
Debt Instrument [Line Items]
Long-term debt	6,392,552	6,413,760
Parent Company [Member]
Debt Instrument [Line Items]
Long-term debt	987,891	986,822
Credit Facility [Member] | Foursight Capital [Member]
Debt Instrument [Line Items]
Long-term debt	97,138	109,501
5.50% Senior Notes due October 18, 2023 [Member]
Debt Instrument [Line Items]
Long-term debt	$ 741,264	$ 740,239
Interest rate	5.50%	5.50%
Maturity date	Oct. 18, 2023	Oct. 18, 2023
Principal	$ 750,000	$ 750,000
6.625% Senior Notes due October 23, 2043 [Member]
Debt Instrument [Line Items]
Long-term debt	$ 246,627	$ 246,583
Interest rate	6.625%	6.625%
Maturity date	Oct. 23, 2043	Oct. 23, 2043
Principal	$ 250,000	$ 250,000
5.5% Senior Notes, due March 15, 2016 [Member]
Debt Instrument [Line Items]
Long-term debt	$ 0	$ 353,025
Interest rate	5.50%	5.50%
Maturity date	Mar. 15, 2016	Mar. 15, 2016
Principal	$ 0	$ 350,000
5.125% Senior Notes, due April 13, 2018 [Member]
Debt Instrument [Line Items]
Long-term debt	$ 817,813	$ 830,298
Interest rate	5.125%	5.125%
Maturity date	Apr. 13, 2018	Apr. 13, 2018
Principal	$ 800,000	$ 800,000
8.5% Senior Notes, due July 15, 2019 [Member]
Debt Instrument [Line Items]
Long-term debt	$ 778,367	$ 806,125
Interest rate	8.50%	8.50%
Maturity date	Jul. 15, 2019	Jul. 15, 2019
Principal	$ 700,000	$ 700,000
2.375% Euro Senior Notes, due May 20, 2020 [Member]
Debt Instrument [Line Items]
Long-term debt	$ 528,250	$ 526,436
Interest rate	2.375%	2.375%
Maturity date	May 20, 2020	May 20, 2020
Principal	$ 529,975	$ 528,625
6.875% Senior Notes, due April 15, 2021 [Member]
Debt Instrument [Line Items]
Long-term debt	$ 823,797	$ 838,765
Interest rate	6.875%	6.875%
Maturity date	Apr. 15, 2021	Apr. 15, 2021
Principal	$ 750,000	$ 750,000
2.25% Euro Medium Term Notes, due July 13, 2022 [Member]
Debt Instrument [Line Items]
Long-term debt	$ 3,848	$ 3,779
Interest rate	2.25%	2.25%
Maturity date	Jul. 13, 2022	Jul. 13, 2022
Principal	$ 4,240	$ 4,229
5.125% Senior Notes, due January 20, 2023 [Member]
Debt Instrument [Line Items]
Long-term debt	$ 618,355	$ 620,890
Interest rate	5.125%	5.125%
Maturity date	Jan. 20, 2023	Jan. 20, 2023
Principal	$ 600,000	$ 600,000
6.45% Senior Debentures, due June 8, 2027 [Member]
Debt Instrument [Line Items]
Long-term debt	$ 377,806	$ 379,711
Interest rate	6.45%	6.45%
Maturity date	Jun. 08, 2027	Jun. 08, 2027
Principal	$ 350,000	$ 350,000
3.875% Convertible Senior Debentures, due November 1, 2029 [Member]
Debt Instrument [Line Items]
Long-term debt	$ 346,163	$ 347,307
Interest rate	3.875%	3.875%	3.875%
Maturity date	Nov. 01, 2029	Nov. 01, 2029
Principal	$ 345,000	$ 345,000
6.25% Senior Debentures, due January 15, 2036 [Member]
Debt Instrument [Line Items]
Long-term debt	$ 512,396	$ 512,730
Interest rate	6.25%	6.25%
Maturity date	Jan. 15, 2036	Jan. 15, 2036
Principal	$ 500,000	$ 500,000
6.50% Senior Notes, due January 20, 2043 [Member]
Debt Instrument [Line Items]
Long-term debt	$ 421,333	$ 421,656
Interest rate	6.50%	6.50%
Maturity date	Jan. 20, 2043	Jan. 20, 2043
Principal	$ 400,000	$ 400,000
Structured Notes [Member]
Debt Instrument [Line Items]
Long-term debt	255,203	0
Long-term debt, fair value	248,900
Debt matures in 2018	6,300
Debt maturities in 2019	10,700
Debt maturities in 2024 or thereafter	238,200
Term Loan [Member] | National Beef [Member]
Debt Instrument [Line Items]
Long-term debt	$ 273,811	310,000
Interest rate	2.60%
Term Loan [Member] | 54 Madison [Member]
Debt Instrument [Line Items]
Long-term debt	$ 406,028	116,211
Revolving Credit Facility [Member] | National Beef [Member]
Debt Instrument [Line Items]
Long-term debt	0	120,080
Other [Member]
Debt Instrument [Line Items]
Long-term debt	$ 132,244	$ 117,246