Investments (Tables)

9 Months Ended

12 Months Ended

Sep. 30, 2011

Dec. 31, 2010

Investments [Abstract]

Investment Securities Stated At Fair Value

			Fair Value Measurements at Reporting Date Using
			Quoted Prices in
			Active Markets		Significant		Significant
			for Identical		Other Observable		Unobservable
	Total as of		Assets		Inputs		Inputs
Description	September 30, 2011		(Level 1)		(Level 2)		(Level 3)
Cash & Cash Equivalents	$	397,105,404	$	397,105,404	$	—	$	—
Short-Term Investments:
Government Securities		59,071,590		59,071,590		—		—
Other		73,748		73,748		—		—
Long-Term Investments:
Common Stocks		50,993,855		50,993,855		—		—
Mutual Funds — Equity		55,060,953		55,060,953		—		—
Certificate of Deposit		505,390		—		505,390		—
Other — Equity		355,700		355,700		—		—
Total	$	563,166,640	$	562,661,250	$	505,390	$	—

			Fair Value Measurements at Reporting Date Using
			Quoted Prices in
			Active Markets		Significant		Significant
			for Identical		Other Observable		Unobservable
	Total as of		Assets		Inputs		Inputs
Description	December 31, 2010		(Level 1)		(Level 2)		(Level 3)
Cash & Cash Equivalents	$	348,349,773	$	348,349,773	$	—	$	—
Short-Term Investments:
Government Securities		36,136,760		36,136,760		—		—
U.S. Treasury Notes		50,156,250		—		50,156,250		—
Other		154,586		154,586		—		—
Long-Term Investments:
Common Stocks		63,637,711		63,637,711		—		—
Mutual Funds — Equity		55,234,901		55,234,901		—		—
Limited Partnership — Equity		9,363,555		—		9,363,555		—
Certificate of Deposit		500,000		—		500,000		—
Other — Equity		355,000		355,000		—		—
Total	$	563,888,536	$	503,868,731	$	60,019,805	$	—

Schedule Of Amortized Cost, Unrealized Gains And Losses, And Market Value Of Investment Securities

			Unrealized
As of September 30, 2011:	Cost		Gains		Losses			Market value
Short-Term Investments:
Government Securities	$	59,062,836	$	12,428	$	(3,674	)	$	59,071,590
Other		73,748		—		—			73,748
Long-Term Investments:
Common Stocks		43,474,434		10,410,611		(2,891,190	)		50,993,855
Mutual Funds-Equity		54,654,154		4,027,553		(3,620,754	)		55,060,953
Certificate of Deposit		505,390		—		—			505,390
Other — Equity		338,506		17,194		—			355,700
Total	$	158,109,068	$	14,467,786	$	(6,515,618	)	$	166,061,236

			Unrealized
As of December 31, 2010:	Cost		Gains		Losses			Market value
Short-Term Investments:
Government Securities	$	36,137,467	$	9,254	$	(9,961	)	$	36,136,760
U.S. Treasury Notes		50,095,921		60,329		—			50,156,250
Other		154,586		—		—			154,586
Long-Term Investments:
Common Stocks		44,899,944		18,819,518		(81,751	)		63,637,711
Mutual Funds-Equity		42,106,776		13,128,125		—			55,234,901
Limited Partnership — Equity		7,844,022		1,519,533		—			9,363,555
Certificate of Deposit		500,000		—		—			500,000
Other — Equity		338,506		16,494		—			355,000
Total	$	182,077,222	$	33,553,253	$	(91,712	)	$	215,538,763

Schedule Of Unrealized Loss On Investments

	Aggregate Unrealized Losses			Aggregate Fair Value
Less than one year	$	(6,515,618	)	$	61,959,268
Greater than one year		—			—

	Aggregate Unrealized Losses			Aggregate Fair Value
Less than one year	$	(91,712	)	$	17,007,886
Greater than one year		—			—

Maturities Of Fixed Income Securities

Due within one year	$	59,145,338
Due between one and five years		505,390
Due over five years		—