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Consolidated Statements of Comprehensive Income (Parenthetical) (USD $)
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12 Months Ended | ||
|---|---|---|---|
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Dec. 31, 2013
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Dec. 31, 2012
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Dec. 31, 2011
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| Statement Of Income And Comprehensive Income [Abstract] | |||
| Cash flow derivative, tax | $ 197,419 | ||
| Transition obligation, tax | 3,089 | ||
| Prior service cost, tax | 21,653 | ||
| Actuarial net gain (loss), tax | $ 629,200 | $ 67,859 | $ 237,412 |