Stock-based compensation (Schedule of stock option activity) (Details) - USD ($)	9 Months Ended		12 Months Ended
	Sep. 30, 2026	Sep. 30, 2025	Dec. 31, 2025	Dec. 31, 2024
Share-based Payment Arrangement [Abstract]
Number of options outstanding, Beginning balance	50,100	23,700	23,700
Number of options, Granted	91,000	16,500
Number of options, Exercised		(2,900)
Number of options, Forfeited	(900)	(150)
Number of options outstanding, Ending balance	140,200	37,150	50,100	23,700
Number of options, Exercisable, end of year	79,075	22,650
Number of options, Unvested	61,125	14,500
Weighted average exercise price, Beginning balance	$ 102.72	$ 73.5	$ 73.5
Weighted average exercise price, Granted	16.37	149.5
Weighted average exercise price, exercised		55.5
Weighted average exercise price, Forfeited	43.91	138
Weighted average exercise price, Ending balance	46.76	108.5	$ 102.72	$ 73.5
Stock options Exercisable, Weighted-average exercise price end of year	72.59	80.5
Stock options Unvested, Weighted average exercise price	$ 13.33	$ 152
Stock options, Granted, Weighted average remaining contractual life (years)	4 years 8 months 19 days	4 years 9 months 21 days
Stock options, Outstanding, Weighted average remaining contractual life (years)	4 years 3 months	4 years 21 days	2 years 9 months	4 years 2 months 4 days
Stock options, Exercisable, Weighted average remaining contractual life (years)	3 years 9 months 25 days	3 years 6 months 25 days
Unvested, Weighted average remaining contractual life (years)	4 years 9 months 18 days	4 years 2 months 4 days
Stock options, Outstanding, Aggregate intrinsic value	$ 0	$ 7.5	$ 0	$ 59
Stock options, Exercisable, Aggregate intrinsic value	0	$ 35
Stock options, Unvested, Aggregate intrinsic value	$ 0