Dividends and Basic Earnings Per Common Share (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended
Mar. 31, 2018	Mar. 31, 2017
Dividends [Abstract]
Cash dividends declared per share of common stock (in dollars per share)	$ 0	$ 0
Earnings per share for the period [Abstract]
Net Income	$ 9,941	$ 7,821
Weighted Average Number of Common Shares Outstanding (in shares)	812,304	807,986
Basic Earnings Per Common Share Amount (in dollars per share)	$ 12.24	$ 9.68

Aggregate dividends declared during the period for each share of common stock outstanding.

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

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Number of [basic] shares or units, after adjustment for contingently issuable shares or units and other shares or units not deemed outstanding, determined by relating the portion of time within a reporting period that common shares or units have been outstanding to the total time in that period.

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