Investments (Schedule of Amortized Cost, Unrealized Gains And Losses, And Market Value of Investment Securities) (Details) - USD ($)	Sep. 30, 2015	Dec. 31, 2014
Schedule of Available-for-sale Securities [Line Items]
Cash & Cash Equivalents	$ 564,528,197	$ 497,429,804
Cost	93,077,387	97,923,092
Unrealized Gains	6,585,055	17,855,921
Unrealized Losses	(5,237,521)	(1,135,425)
Market Value	94,424,921	114,643,588
Investments and Cash	658,953,118	612,073,392
Short-term Investments [Member] \| Other Debt Obligations [Member]
Schedule of Available-for-sale Securities [Line Items]
Cost	335	1,021
Unrealized Gains	0	0
Unrealized Losses	0	0
Market Value	335	1,021
Long-Term Investments [Member] \| Common Stock
Schedule of Available-for-sale Securities [Line Items]
Cost	21,181,972	17,069,742
Unrealized Gains	4,667,521	7,933,717
Unrealized Losses	(1,720,996)	(355,008)
Market Value	24,128,497	24,648,451
Long-Term Investments [Member] \| Mutual Funds – Equity
Schedule of Available-for-sale Securities [Line Items]
Cost	71,895,080	80,852,329
Unrealized Gains	1,917,534	9,922,204
Unrealized Losses	(3,516,525)	(780,417)
Market Value	70,296,089	89,994,116
Fair Value, Inputs, Level 1 [Member]
Schedule of Available-for-sale Securities [Line Items]
Cash & Cash Equivalents	564,528,197	497,429,804
Investments and Cash	658,953,118	612,073,392
Fair Value, Inputs, Level 1 [Member] \| Short-term Investments [Member] \| Other Debt Obligations [Member]
Schedule of Available-for-sale Securities [Line Items]
Market Value	335	1,021
Fair Value, Inputs, Level 1 [Member] \| Long-Term Investments [Member] \| Common Stock
Schedule of Available-for-sale Securities [Line Items]
Market Value	24,128,497	24,648,451
Fair Value, Inputs, Level 1 [Member] \| Long-Term Investments [Member] \| Mutual Funds – Equity
Schedule of Available-for-sale Securities [Line Items]
Market Value	70,296,089	89,994,116
Fair Value, Inputs, Level 2 [Member]
Schedule of Available-for-sale Securities [Line Items]
Cash & Cash Equivalents	0	0
Investments and Cash	0	0
Fair Value, Inputs, Level 2 [Member] \| Short-term Investments [Member] \| Other Debt Obligations [Member]
Schedule of Available-for-sale Securities [Line Items]
Market Value	0	0
Fair Value, Inputs, Level 2 [Member] \| Long-Term Investments [Member] \| Common Stock
Schedule of Available-for-sale Securities [Line Items]
Market Value	0	0
Fair Value, Inputs, Level 2 [Member] \| Long-Term Investments [Member] \| Mutual Funds – Equity
Schedule of Available-for-sale Securities [Line Items]
Market Value	0	0
Fair Value, Inputs, Level 3 [Member]
Schedule of Available-for-sale Securities [Line Items]
Cash & Cash Equivalents	0	0
Investments and Cash	0	0
Fair Value, Inputs, Level 3 [Member] \| Short-term Investments [Member] \| Other Debt Obligations [Member]
Schedule of Available-for-sale Securities [Line Items]
Market Value	0	0
Fair Value, Inputs, Level 3 [Member] \| Long-Term Investments [Member] \| Common Stock
Schedule of Available-for-sale Securities [Line Items]
Market Value	0	0
Fair Value, Inputs, Level 3 [Member] \| Long-Term Investments [Member] \| Mutual Funds – Equity
Schedule of Available-for-sale Securities [Line Items]
Market Value	$ 0	$ 0

Amount before tax of unrealized gain in accumulated other comprehensive income (AOCI) on investments in debt and equity securities classified as available-for-sale.

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 320

-SubTopic 10

-Section 50

-Paragraph 2

-Subparagraph (b)

-URI http://asc.fasb.org/extlink&oid=27724398&loc=d3e27161-111563

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Amount before tax of unrealized loss in accumulated other comprehensive income (AOCI) on investments in debt and equity securities classified as available-for-sale.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

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-SubTopic 10

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This item represents the cost of debt and equity securities, which are categorized neither as held-to-maturity nor trading, net of adjustments including accretion, amortization, collection of cash, previous other-than-temporary impairments recognized in earnings (less any cumulative-effect adjustments recognized, as defined), and fair value hedge accounting adjustments, if any.

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Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 210

-SubTopic 10

-Section S99

-Paragraph 1

-Subparagraph (SX 210.5-02.2)

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Fair value portion of currency on hand as well as demand deposits with banks or financial institutions. Includes other kinds of accounts that have the general characteristics of demand deposits. Also includes short-term, highly liquid investments that are both readily convertible to known amounts of cash and so near their maturity that they present insignificant risk of changes in value because of changes in interest rates.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Glossary Cash

-URI http://asc.fasb.org/extlink&oid=6506951

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-Name Accounting Standards Codification

-Glossary Cash Equivalents

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Sum of investments and unrestricted cash as of the balance sheet date.

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-Publisher FASB

-Name Accounting Standards Codification

-Topic 944

-SubTopic 210

-Section S99

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Fair value portion of investment securities, including, but not limited to, marketable securities, derivative financial instruments, and investments accounted for under the equity method.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Glossary Trading Securities

-URI http://asc.fasb.org/extlink&oid=6526789

Reference 2: http://www.xbrl.org/2003/role/presentationRef

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-Name Accounting Standards Codification

-Topic 320

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-Name Accounting Standards Codification

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-SubTopic 10

-Section 25

-Paragraph 1

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-Glossary Available-for-Sale Securities

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-Name Regulation S-X (SX)

-Number 210

-Section 03

-Paragraph 1

-Subparagraph a, f, g

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Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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