Note 4 - Capital Stock (Details Textual) - USD ($) $ / shares in Units, $ in Thousands			1 Months Ended	12 Months Ended
	Feb. 23, 2024	Feb. 04, 2023	Feb. 24, 2024	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Common Stock, Dividends, Per Share, Declared		$ 0.42
Treasury Stock, Shares, Acquired				902,100
Treasury Stock, Value, Acquired, Cost Method				$ 159,576	$ 300,030	$ 151,720
Stock Repurchase Program, Remaining Authorized Repurchase Amount				$ 391,500
Exercise or Vesting [Member]
Common Stock, Capital Shares Reserved for Future Issuance (in shares)				1,300,000
Future Issuance [Member]
Common Stock, Capital Shares Reserved for Future Issuance (in shares)				3,900,000
Subsequent Event [Member]
Common Stock, Dividends, Per Share, Declared			$ 0.43
Dividends Payable, Date to be Paid	Feb. 23, 2024
Dividends Payable, Date of Record	Feb. 09, 2024