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Comprehensive Income (AOCI Rollforward) (Details) (USD $) | 12 Months Ended
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Dec. 31, 2013 | Dec. 31, 2012 | Dec. 31, 2011
Accumulated Other Comprehensive Income (Loss) [Roll Forward] |  |  |
Balance at beginning of period | $ 17,570,711 | $ 12,542,203 |
Comprehensive Income | 227,334,601 | 173,615,348 | 154,893,528
Balance at end of period | 21,975,363 | 17,570,711 | 12,542,203
Foreign currency translation adjustments: |  |  |
Accumulated Other Comprehensive Income (Loss) [Roll Forward] |  |  |
Balance at beginning of period | 2,458,933 | 2,129,957 | 566,903
Other Comprehensive income before reclassifications | 48,989 | 328,976 | 1,563,054
Amounts reclassified from accumulated other comprehensive income | 0 | 0 | 0
Comprehensive Income | 48,989 | 328,976 | 1,563,054
Balance at end of period | 2,507,922 | 2,458,933 | 2,129,957
Unrealized gains(losses) on available-for-sale securities: |  |  |
Accumulated Other Comprehensive Income (Loss) [Roll Forward] |  |  |
Balance at beginning of period | 15,111,778 | 10,412,246 | 21,750,000
Other Comprehensive income before reclassifications | 16,139,845 | 10,138,902 | (7,012,974)
Amounts reclassified from accumulated other comprehensive income | (11,784,182) | (5,439,370) | (4,324,780)
Comprehensive Income | 4,355,663 | 4,699,532 | (11,337,754)
Balance at end of period | $ 19,467,441 | $ 15,111,778 | $ 10,412,246

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- Definition Accumulated change in equity from transactions and other events and circumstances from non-owner sources, net of tax effect, at period end. Excludes Net Income (Loss), and accumulated changes in equity from transactions resulting from investments by owners and distributions to owners. Includes foreign currency translation items, certain pension adjustments, unrealized gains and losses on certain investments in debt and equity securities, other than temporary impairment (OTTI) losses related to factors other than credit losses on available-for-sale and held-to-maturity debt securities that an entity does not intend to sell and it is not more likely than not that the entity will be required to sell before recovery of the amortized cost basis, as well as changes in the fair value of derivatives related to the effective portion of a designated cash flow hedge. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 220 -SubTopic 10 -Section 45 -Paragraph 14A -URI http://asc.fasb.org/extlink&oid=28358780&loc=SL7669686-108580 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 220 -SubTopic 10 -Section 45 -Paragraph 11 -URI http://asc.fasb.org/extlink&oid=28358780&loc=d3e637-108580 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 220 -SubTopic 10 -Section 45 -Paragraph 14 -URI http://asc.fasb.org/extlink&oid=28358780&loc=d3e681-108580 Reference 4: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 02 -Paragraph 31 -Article 5 Reference 5: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 04 -Article 3 + Details
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- Definition Amount after tax of increase (decrease) in equity from transactions and other events and circumstances from net income and other comprehensive income, attributable to parent entity. Excludes changes in equity resulting from investments by owners and distributions to owners. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Glossary Other Comprehensive Income -URI http://asc.fasb.org/extlink&oid=6519514 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Glossary Comprehensive Income -URI http://asc.fasb.org/extlink&oid=16317811 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 220 -SubTopic 10 -Section 45 -Paragraph 5 -URI http://asc.fasb.org/extlink&oid=28358780&loc=d3e557-108580 Reference 4: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Glossary Net Income -URI http://asc.fasb.org/extlink&oid=6518256 + Details
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