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Investments (Investments Classified by Contractual Maturity Date) (Details) - Fixed Income Securities	Jun. 30, 2019 USD ($)
Debt Securities, Available-for-sale [Line Items]
Due within one year	$ 189,280,485
Due between one and five years	91,584,216
Due over five years	21,877,006
Total	$ 302,741,707

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Fair value of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), with single maturity date and allocated without single maturity date, maturing in second through fifth fiscal year following latest fiscal year. Excludes interim and annual periods when interim period is reported on rolling approach, from latest statement of financial position date.

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Amount of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

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