Mezzanine Equity (Narrative) (Details) - USD ($)		3 Months Ended				9 Months Ended
	Jun. 05, 2018	Sep. 30, 2018	Jun. 30, 2018	Sep. 30, 2017	Jun. 30, 2017	Sep. 30, 2018	Sep. 30, 2017	Dec. 31, 2017
Purchase Requirement [Line Items]
Reversal of cumulative National Beef redeemable noncontrolling interests fair value adjustments prior to deconsolidation						$ 237,669,000
Redeemable noncontrolling interests		$ 21,400,000				21,400,000		$ 14,500,000
Mandatorily redeemable convertible preferred shares redemption value		$ 125,000,000				$ 125,000,000		$ 125,000,000
Dividends per common share (in dollars per share)		$ 0.125	$ 0.10	$ 0.10	$ 0.0625	$ 0.325	$ 0.225
Preferred stock dividend		$ 1,276,000		$ 1,172,000		$ 3,619,000	$ 3,203,000
3.25% Cumulative Convertible Preferred Shares
Purchase Requirement [Line Items]
Dividend rate on preferred stock						3.25%
Mandatorily redeemable convertible preferred shares redemption value		$ 125,000,000.0				$ 125,000,000.0
Mandatorily redeemable preferred stock, number of shares in conversion		4,162,200				4,162,200
Mandatorily redeemable preferred stock, effective conversion price per share		$ 30.03				$ 30.03
Minimum dividend considered for additional quarterly payments		0.0625				$ 0.0625
Preferred stock dividend						$ 3,600,000	$ 3,200,000
Mandatorily redeemable preferred shares callable price per share		$ 1,000				$ 1,000
Discontinued operations, disposed of by sale | National Beef
Purchase Requirement [Line Items]
Percentage of ownership owned	48.00%
Reversal of cumulative National Beef redeemable noncontrolling interests fair value adjustments prior to deconsolidation	$ 237,700,000