Note 12 - Stockholders' Equity (Details Textual) - USD ($)				3 Months Ended				9 Months Ended
	Oct. 26, 2021	Aug. 04, 2021	Jul. 16, 2021	Sep. 30, 2021	Mar. 31, 2021	Sep. 30, 2020	Mar. 31, 2020	Sep. 30, 2021	Sep. 30, 2020	Feb. 23, 2021	Dec. 31, 2020
Stock Issued During Period, Shares, New Issues (in shares)			1,000,000
Common Stock, Par or Stated Value Per Share (in dollars per share)			$ 0.01	$ 0.01				$ 0.01			$ 0.01
Shares Issued, Price Per Share (in dollars per share)			$ 54.50
Stock Issued During Period, Value, New Issues			$ 51,000,000.0	$ 58,695,000
Proceeds from Issuance of Common Stock								$ 61,566,000	$ 1,437,000
Common Stock, Dividends, Per Share, Declared (in dollars per share)				$ 0.110		$ 0.095		$ 0.330	$ 0.285
Subsequent Event [Member]
Common Stock, Dividends, Per Share, Declared (in dollars per share)	$ 0.11
Dividends Payable	$ 2,400,000
Dividends Payable, Date of Record	Oct. 26, 2021
Dividends Payable, Date to be Paid	Dec. 02, 2021
Common Stock [Member]
Stock Issued During Period, Shares, New Issues (in shares)				1,150,000
Stock Issued During Period, Value, New Issues				$ 12,000
Treasury Stock, Shares, Acquired (in shares)
Stock Repurchase Program [Member] | Common Stock [Member]
Stock Repurchase Program, Authorized Amount										$ 15,000,000.0
Treasury Stock, Shares, Acquired (in shares)								0
Underwriters [Member]
Stock Issued During Period, Value, New Issues		$ 150,000
Proceeds from Issuance of Common Stock		$ 7,600,000