Earnings per share (Details) - USD ($)	12 Months Ended
Dec. 31, 2018	Dec. 31, 2017
Numerator:
Net income attributable to the Company	$ 13,154,581	$ 16,772,852
Weighted-average shares outstanding
- Basic	15,546,644	15,326,797
- Dilutive effects of equity incentive awards	59,533	108,574
- Diluted	15,606,177	15,435,371
Net income per share:
- Basic	$ 0.85	$ 1.09
- Diluted	$ 0.84	$ 1.09

The amount of net income (loss) for the period per each share of common stock or unit outstanding during the reporting period.

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+ Details

- Definition

The amount of net income (loss) for the period available to each share of common stock or common unit outstanding during the reporting period and to each share or unit that would have been outstanding assuming the issuance of common shares or units for all dilutive potential common shares or units outstanding during the reporting period.

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+ Details

- Definition

The portion of profit or loss for the period, net of income taxes, which is attributable to the parent.

+ References + Details