Segment Information (Narrative) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Segment Reporting Information [Line Items]
Net realized securities gains	$ 62,957	$ 30,394	$ 243,957
Interest expense	111,412	117,174	84,964
Corporate and Other [Member]
Segment Reporting Information [Line Items]
Net realized securities gains	63,000	30,400	16,000
Inmet Mining Corporation [Member]
Segment Reporting Information [Line Items]
Net realized securities gains			227,600
National Beef [Member]
Segment Reporting Information [Line Items]
Interest expense	16,000	14,500	12,300
Parent Company [Member]
Segment Reporting Information [Line Items]
Interest expense	$ 85,900	$ 98,100	$ 72,200