Note 6 - Stockholders' Equity (Details Textual) $ / shares in Units, $ in Millions	12 Months Ended
	Dec. 31, 2023 USD ($) $ / shares shares	Dec. 31, 2022 USD ($) $ / shares shares	Dec. 31, 2021 USD ($) $ / shares shares
Capital Units, Authorized (in shares)	245,000,000
Common Stock, Shares Authorized (in shares)	200,000,000
Preferred Stock, Shares Authorized (in shares)	20,000,000
Common Stock, Voting Rights, Votes Per Share	1
Common Stock, Dividends, Per Share, Declared (in dollars per share) | $ / shares	$ 0.32	$ 0.32	$ 0.32
Common Stock, Capital Shares Reserved for Future Issuance (in shares)	5,000,000
Treasury Stock, Value, Acquired, Cost Method | $	$ (0)	$ 50	$ 30
Class A Common Stock (No Par Value) [Member]
Common Stock, Shares Authorized (in shares)	25,000,000	25,000,000
Common Stock, Voting Rights, Votes Per Share	10
Common Stock, Capital Shares Reserved for Future Issuance (in shares)	2,000,000
Stock Repurchased During Period, Shares (in shares)	0
Common Stock and Class A Common Stock [Member]
Stock Repurchased During Period, Shares (in shares)		2,600,000	1,500,000
Treasury Stock, Value, Acquired, Cost Method | $		$ 50	$ 30