Note 5 - Share-based Compensation - Restricted Share Units (Details) - Restricted Stock Units (RSUs) [Member]	12 Months Ended
	Dec. 31, 2025 $ / shares shares
Number of shares unvested at beginning of period (in shares) | shares	737,237
Number of shares unvested at beginning of period, weighted average grant date fair value (in dollars per share) | $ / shares	$ 163.83
Number of shares granted (in shares) | shares	344,140
Number of shares granted, weighted average grant date fair value (in dollars per share) | $ / shares	$ 162.66
Number of shares vested (in shares) | shares	(372,223)
Number of shares vested, weighted average grant date fair value (in dollars per share) | $ / shares	$ 157.29
Number of shares forfeited (in shares) | shares	(24,147)
Number of shares forfeited, weighted average grant date fair value (in dollars per share) | $ / shares	$ 181.65
Number of shares unvested at end of period (in shares) | shares	685,007
Number of shares unvested at end of period, weighted average grant date fair value (in dollars per share) | $ / shares	$ 166.14