Note 8 - Marketable Securities (Details Textual) - USD ($) $ / shares in Units, $ in Thousands, shares in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Proceeds from Sale and Maturity of Marketable Securities	$ 292,552	$ 302,504	$ 377
Albertsons Companies, Inc [Member]
Dividend Income, Equity Securities, Operating	$ 194,100
Marketable Securities, Cash Dividend Receivable, Per Share (in dollars per share)	$ 0.09
Sale of Marketable Securities (in shares)	14.1	11.5
Proceeds from Sale and Maturity of Marketable Securities	$ 282,300	$ 301,100
Equity Securities, FV-NI, Realized Gain (Loss)	241,200	251,500
Equity Securities, Taxes Paid on Capital Gains	$ 60,900	$ 57,200
Investment Owned, Balance, Shares (in shares)	14.2