Note 9 - Marketable Securities (Details Textual) - USD ($) $ / shares in Units, $ in Thousands, shares in Millions		1 Months Ended	12 Months Ended
	Jun. 25, 2020	Jun. 30, 2020	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Marketable Securities, Gain (Loss), Total			$ 505,163	$ 594,753	$ 829
Investment Income, Dividend			17,000	4,100
Proceeds from Sale of Cost Method Investments			0	227,270	0
Realized Investment Gains (Losses), Total			0	190,832	$ 0
Marketable Securities, Total			$ 1,211,739	706,954
Albertsons Companies, Inc [Member]
Proceeds from Issuance of Convertible Preferred Stock		$ 1,680,000
Percentage of Ownership to Be Purchased		17.50%
Albertsons Companies, Inc [Member] | IPO [Member]
Stock Issued During Period, Shares, New Issues (in shares)	50.0
Sale of Stock, Price Per Share (in dollars per share)	$ 16.00
Albertsons Companies, Inc [Member] | Convertible Preferred Stock [Member]
Stock Issued During Period, Value, New Issues		$ 1,750,000
Albertsons Companies, Inc [Member]
Percentage of Ownership in Cost Method Investment		7.50%	9.29%
Proceeds from Sale of Cost Method Investments	$ 71,400	$ 156,100
Realized Investment Gains (Losses), Total	$ 59,200	$ 131,600
Shares Sold in Cost Method Investments (in shares)	4.7
Investment Owned, Balance, Shares (in shares)			39.8
Marketable Securities, Total			$ 1,200,000	700,400
Marketable Securities, Unrealized Gain (Loss), Total			1,100,000	$ 596,800
Albertsons Companies, Inc [Member] | Other Assets [Member]
Other Investments and Securities, at Cost			$ 140,200