3. Income Per Share (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended	6 Months Ended
Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Earnings Per Share [Abstract]
Net income	$ 10,026	$ 7,450	$ 19,976	$ 14,396
Weighted average basic shares outstanding	1,844	1,822	1,839	1,823
Add: Effect of dilutive securities	14	31	17	32
Weighted average diluted shares outstanding	1,858	1,853	1,856	1,855
Earnings per share:
Basic	$ 5.44	$ 4.09	$ 10.86	$ 7.9
Diluted	$ 5.4	$ 4.02	$ 10.76	$ 7.76

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

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The sum of dilutive potential common shares or units used in the calculation of the diluted per-share or per-unit computation.

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The average number of shares or units issued and outstanding that are used in calculating diluted EPS or earnings per unit (EPU), determined based on the timing of issuance of shares or units in the period.

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