Stock-based compensation (Details) - USD ($)	12 Months Ended
	Dec. 31, 2025	Dec. 31, 2024	Dec. 31, 2023	May 14, 2008
Stock-based compensation
Number of days employee option to purchase preferred stock must be exercised	30 days
Preferred stock value	$ 23,704	$ 26,402
Number of stock grant rights issued	10,229
Allocated share-based compensation expense, net	$ 390,282	142,566	$ 703,289
Closing price of the common shares	$ 35.29
Number of shares outstanding, options, Nonvested	9,670
Weighted average exercise price, Nonvested	$ 22.08
Average remaining contractual life, Nonvested	1 year 8 months 8 days
Total remaining unrecognized compensation costs	$ 33,222
Total remaining unrecognized compensation, weighted average period	1 year 8 months 8 days
Compensation expense relating to stock and stock option grants	$ 1,701,904	$ 1,397,583	$ 1,933,666
Stock issued for services rendered	$ 69,440
Non-performance-based
Stock-based compensation
Number of stock grant rights issued	17,275	12,837	29,508
Vesting period	3 years
Number of vested shares issued	$ 24,875	$ 29,392	$ 25,986
Allocated share-based compensation expense	$ 423,923	412,520	366,058
Cumulative financial performance targets measurement period	3 years
Non Executive Directors Share Plan
Stock-based compensation
Compensation expense relating to stock and stock option grants	$ 372,752	$ 333,140	$ 341,394
Performance-Based Grants
Stock-based compensation
Number of stock grant rights issued	35,981	41,889	26,742
Cumulative financial performance targets measurement period	3 years	3 years	3 years
Compensation expense relating to stock and stock option grants	$ 514,947	$ 509,357	$ 522,925
Employee Stock Option | Common Stock Options
Stock-based compensation
Preferred stock value	$ 0
Number of stock grant rights issued	1,695	1,300	3,010
Equity Incentive Plan 2008
Stock-based compensation
Common stock, capital shares reserved for future issuance				1,500,000
Redeemable preferred stock
Stock-based compensation
Additional consecutive individual requisite service period required for eligibility in Employee Share Incentive Plan	4 years
Number of preferred shares converted to common shares dependent upon specific criteria	1
Number of common shares received upon conversion of preferred shares dependent upon specific criteria	1
Number of average trading price of the common stock	7 days
Issuance of common stock for services rendered	8,534	5,904	13,309
Preferred stock value	$ 0
Redeemable preferred stock | Non Executive Directors Share Plan
Stock-based compensation
Number of stock grant rights issued	13,897	11,448	22,831
Common stock
Stock-based compensation
Issuance of common stock for services rendered	2,000
Stock issued for services rendered	$ 69,440,000