Investments (Schedule of Amortized Cost, Unrealized Gains And Losses, And Market Value of Investment Securities) (Details) (USD $)	Sep. 30, 2013	Dec. 31, 2012
Schedule of Available-for-sale Securities [Line Items]
Cost	$ 83,902,235	$ 179,388,001
Unrealized Gains	30,514,997	23,937,617
Unrealized Losses	(146,609)	(688,728)
Investments	114,270,623	202,636,890
Short-Term Investments [Member] | Government Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Cost		38,514,411
Unrealized Gains		9,004
Unrealized Losses		(944)
Investments		38,522,471
Short-Term Investments [Member] | U.S. Treasury Notes [Member]
Schedule of Available-for-sale Securities [Line Items]
Cost		15,018,810
Unrealized Gains		2,602
Unrealized Losses		(1,062)
Investments		15,020,350
Short-Term Investments [Member] | Corporate Bond Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Cost		6,529,758
Unrealized Gains		33,470
Unrealized Losses		0
Investments		6,563,228
Short-Term Investments [Member] | Other [Member]
Schedule of Available-for-sale Securities [Line Items]
Cost		185,926
Unrealized Gains		0
Unrealized Losses		0
Investments		185,926
Short-Term Investments [Member] | Certificate Of Deposit [Member]
Schedule of Available-for-sale Securities [Line Items]
Cost		510,881
Unrealized Gains		0
Unrealized Losses		0
Investments		510,881
Long-Term Investments [Member] | Corporate Bond Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Cost		2,174,948
Unrealized Gains		5,832
Unrealized Losses		0
Investments		2,180,780
Long-Term Investments [Member] | Common Stocks [Member]
Schedule of Available-for-sale Securities [Line Items]
Cost	27,830,723	40,893,121
Unrealized Gains	9,962,493	12,781,501
Unrealized Losses	(146,609)	(391,421)
Investments	37,646,607	53,283,201
Long-Term Investments [Member] | Mutual Funds - Equity [Member]
Schedule of Available-for-sale Securities [Line Items]
Cost	56,071,512	75,321,640
Unrealized Gains	20,552,504	11,082,714
Unrealized Losses	0	(295,301)
Investments	76,624,016	86,109,053
Long-Term Investments [Member] | Other - Equity [Member]
Schedule of Available-for-sale Securities [Line Items]
Cost		238,506
Unrealized Gains		22,494
Unrealized Losses		0
Investments		$ 261,000