Stock-based compensation (Details) - USD ($)	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022	May 14, 2008
Stock-based compensation
Number of days employee option to purchase preferred stock must be exercised	30 days
Preferred stock value	$ 26,402	$ 26,578
Number of stock grant rights issued	7,204
Allocated share-based compensation expense, net	$ 142,566	$ 703,289	$ 386,260
Closing price of the common shares	$ 25.89
Number of shares outstanding, options, Nonvested	13,475
Weighted average exercise price, Nonvested	$ 16.97
Average remaining contractual life, Nonvested	1 year 6 months 4 days
Total remaining unrecognized compensation costs	$ 32,423
Total remaining unrecognized compensation, weighted average period	1 year 6 months 4 days
Cumulative financial performance targets measurement period		3 years
Compensation expense relating to stock and stock option grants	$ 1,397,583	$ 1,933,666	$ 1,417,172
Non-performance-based
Stock-based compensation
Number of stock grant rights issued	12,837	29,508	32,265
Vesting period	3 years
Number of vested shares issued	$ 29,392	$ 25,986	$ 23,411
Allocated share-based compensation expense	$ 412,520	366,058	$ 325,270
Cumulative financial performance targets measurement period	3 years
Non Executive Directors Share Plan
Stock-based compensation
Number of stock grant rights issued			30,767
Compensation expense relating to stock and stock option grants	$ 333,140	$ 341,394	$ 369,678
Performance-Based Grants
Stock-based compensation
Number of stock grant rights issued	41,889	26,742	13,797
Cumulative financial performance targets measurement period	3 years	3 years	3 years
Compensation expense relating to stock and stock option grants	$ 509,357	$ 522,925	$ 335,964
Employee Stock Option | Common Stock Options
Stock-based compensation
Number of stock grant rights issued	1,300	3,010	3,665
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	5,904	13,309	9,295
Redeemable preferred stock | Non Executive Directors Share Plan
Stock-based compensation
Number of stock grant rights issued	11,448	22,831