Note 8 - Stockholders' Equity (Details Textual) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Oct. 31, 2023	Dec. 31, 2022
Dividends Payable, Current	$ 47,900		$ 35,300
Accrued Dividend Equivalents	$ 11,900		$ 13,800
Stock Repurchased and Retired During Period, Shares (in shares)	7,000
Stock Repurchased and Retired During Period, Value	$ 3,741
Maximum [Member]
Stock Repurchase Program, Authorized Amount		$ 640,000