Note 6 - Stockholders' Equity (Details Textual) $ / shares in Units, $ in Millions	3 Months Ended				6 Months Ended
	Jun. 30, 2023 USD ($) $ / shares shares	Mar. 31, 2023 USD ($)	Jun. 30, 2022 USD ($) $ / shares	Mar. 31, 2022 USD ($)	Jun. 30, 2023 USD ($) $ / shares shares	Jun. 30, 2022 USD ($) $ / shares	Dec. 31, 2022 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	$ 0.08		$ 0.08		$ 0.16	$ 0.16
Dividends, Common Stock | $	$ 7	$ 7	$ 8	$ 8	$ 14	$ 16
Common Stock, Capital Shares Reserved for Future Issuance (in shares)	7,900,000				7,900,000
Class A Common Stock (No Par Value) [Member]
Common Stock, Shares Authorized (in shares)	25,000,000				25,000,000		25,000,000
Common Stock, Voting Rights, Votes Per Share							10
Common Stock, Dividends, Per Share, Declared (in dollars per share) | $ / shares	$ 0.08
Common Stock, Capital Shares Reserved for Future Issuance (in shares)	2,100,000				2,100,000