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Marketable Securities (Fair Value Of Marketable Securities By Maturity) (Details) (USD $)
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Sep. 30, 2012
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Mar. 31, 2012
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| Marketable Securities [Abstract] | ||
| Marketable securities, Total, fair value | $ 77,927,297 | $ 71,996,927 |
| Marketable securities, debt maturities due within one year, fair value | 15,907,264 | |
| Marketable securities, debt maturities due after one year through three years, fair value | 24,526,863 | |
| Marketable securities, debt maturities due after three years through five years, fair value | $ 37,493,170 |