Investments (Investment Securities Stated At Fair Value) (Details) (USD $)	Sep. 30, 2012	Dec. 31, 2011
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash & Cash Equivalents	$ 381,101,955	$ 357,986,774
Investments	166,610,176	188,976,402
Total	547,712,131	546,963,176
Fair Value, Inputs, Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash & Cash Equivalents	381,101,955	357,986,774
Total	541,387,529	520,764,582
Fair Value, Inputs, Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total	6,324,602	26,198,594
Short-Term Investments [Member] | Government Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments	21,298,865	35,024,030
Short-Term Investments [Member] | Government Securities [Member] | Fair Value, Inputs, Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments	21,298,865	35,024,030
Short-Term Investments [Member] | U.S. Treasury Notes [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments		25,044,000
Short-Term Investments [Member] | U.S. Treasury Notes [Member] | Fair Value, Inputs, Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments		25,044,000
Short-Term Investments [Member] | Corporate Bond Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments		649,204
Short-Term Investments [Member] | Corporate Bond Securities [Member] | Fair Value, Inputs, Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments		649,204
Short-Term Investments [Member] | Other [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments	223,434	91,003
Short-Term Investments [Member] | Other [Member] | Fair Value, Inputs, Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments	223,434	91,003
Long-Term Investments [Member] | Government Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments	5,001,700
Long-Term Investments [Member] | Government Securities [Member] | Fair Value, Inputs, Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments	5,001,700
Long-Term Investments [Member] | Corporate Bond Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments	5,813,721
Long-Term Investments [Member] | Corporate Bond Securities [Member] | Fair Value, Inputs, Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments	5,813,721
Long-Term Investments [Member] | Common Stocks [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments	53,999,028	53,554,303
Long-Term Investments [Member] | Common Stocks [Member] | Fair Value, Inputs, Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments	53,999,028	53,554,303
Long-Term Investments [Member] | Mutual Funds - Equity [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments	79,157,147	73,749,772
Long-Term Investments [Member] | Mutual Funds - Equity [Member] | Fair Value, Inputs, Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments	79,157,147	73,749,772
Long-Term Investments [Member] | Certificate Of Deposit [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments	510,881	505,390
Long-Term Investments [Member] | Certificate Of Deposit [Member] | Fair Value, Inputs, Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments	510,881	505,390
Long-Term Investments [Member] | Other - Equity [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments	605,400	358,700
Long-Term Investments [Member] | Other - Equity [Member] | Fair Value, Inputs, Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments	$ 605,400	$ 358,700