Note 6 - Marketable Securities (Details Textual) - USD ($) $ in Thousands, shares in Millions		3 Months Ended
	Apr. 01, 2023	Jun. 30, 2023	Mar. 31, 2023	Mar. 31, 2022	Dec. 31, 2022
Marketable Securities, Gain (Loss)			$ (10,144)	$ 121,764
Dividend Income, Equity Securities, Operating			194,100
Proceeds from Sale and Maturity of Marketable Securities			138,207	$ 100
Marketable Securities			$ 451,583		$ 597,732
Albertsons Companies, Inc [Member]
Sale of Marketable Securities (in shares)			7.1
Proceeds from Sale and Maturity of Marketable Securities			$ 137,400
Equity Securities, FV-NI, Realized Gain (Loss)			115,400
Equity Securities, Federal and State Taxes Payable on Capital Gains			$ 30,000
Investment Owned, Balance, Shares (in shares)			21.2
Marketable Securities			$ 440,800
Albertsons Companies, Inc [Member] | Forecast [Member]
Equity Securities, FV-NI, Realized Gain (Loss)		$ 125,900
Albertsons Companies, Inc [Member] | Subsequent Event [Member]
Sale of Marketable Securities (in shares)	7.0
Proceeds from Sale and Maturity of Marketable Securities	$ 144,900
Equity Securities, Federal and State Taxes Payable on Capital Gains	$ 32,700