Earnings Per Share (Details) (USD $)	12 Months Ended
Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Computation for earnings per share
Net income	$ 31,580,931us-gaap_NetIncomeLoss	$ 22,154,828us-gaap_NetIncomeLoss	$ 16,930,892us-gaap_NetIncomeLoss
Weighted average number of outstanding shares
Basic (in shares)	3,196,127	3,142,083	3,111,328
Incremental Common Shares Attributable to Dilutive Effect of Nonvested Shares with Forfeitable Dividends	67,453	52,180	0
Incremental Common Shares Attributable to Dilutive Effect of Share-based Payment Arrangements	2,588	0	0
Diluted (in shares)	3,266,168	3,194,263	3,111,328
Earnings per share
Basic (per share)	$ 9.88us-gaap_EarningsPerShareBasic	$ 7.05us-gaap_EarningsPerShareBasic	$ 5.44us-gaap_EarningsPerShareBasic
Diluted (per share)	$ 9.67us-gaap_EarningsPerShareDiluted	$ 6.94us-gaap_EarningsPerShareDiluted	$ 5.44us-gaap_EarningsPerShareDiluted

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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