Investments (Tables)

3 Months Ended

Mar. 31, 2018

Investments [Abstract]

Investment Securities Stated at Fair Value

As of March 31, 2018:

			Fair Value Measurements at Reporting Date Using
	Total as of		Quoted Prices in Active Markets for Identical Assets		Significant Other Observable Inputs		Significant Unobservable Inputs
Description	March 31, 2018		(Level 1)		(Level 2)		(Level 3)
Cash & Cash Equivalents	$	524,323,560	$	524,323,560	$	—	$	—
Short-Term Investments:
Certificate of Deposit	130,000,000		130,000,000		—		—
Corporate Bonds	15,891,817		—		15,891,817		—
Government Securities	6,003,510		—		6,003,510		—
Other	284,081		284,081		—		—
Long-Term Investments:
Common Stocks	40,000		40,000		—		—
Total	$	676,542,968	$	654,647,641	$	21,895,327	$	—

As of December 31, 2017:

			Fair Value Measurements at Reporting Date Using
	Total as of		Quoted Prices in Active Markets for Identical Assets		Significant Other Observable Inputs		Significant Unobservable Inputs
Description	December 31, 2017		(Level 1)		(Level 2)		(Level 3)
Cash & Cash Equivalents	$	569,734,496	$	569,734,496	$	—	$	—
Short-Term Investments:
Certificate of Deposit	130,000,000		130,000,000		—		—
Government Securities	9,011,130		—		9,011,130		—
Mutual Funds	393,581		—		393,581		—
Corporate Bonds	12,944,999		—		12,944,999		—
Other	188,344		188,344		—		—
Long-Term Investments:
Corporate Bonds	3,018,720		—		3,018,720		—
Common Stocks	15,703,371		15,703,371		—		—
Mutual Funds	34,681,337		34,681,337		—		—
Preferred Stock	1,178,991		1,178,991		—		—
Total	$	776,854,969	$	751,486,539	$	25,368,430	$	—

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

As of March 31, 2018:

			Unrealized
	Cost		Gains		Losses		Market Value
Short-Term Investments:
Certificate of Deposit	$	130,000,000	$	—	$	—	$	130,000,000
Government Securities	6,009,310		—		(5,800)		6,003,510
Corporate Bonds	15,919,177		—		(27,360)		15,891,817
Other	284,081		—		—		284,081
Long-Term Investments:
Common Stocks	40,000		—		—		40,000
Total	$	152,252,568	$	—	$	(33,160)	$	152,219,408

As of December 31, 2017:

			Unrealized
	Cost		Gains		Losses		Market Value
Short-Term Investments:
Certificate of Deposit	$	130,000,000	$	—	$	—	$	130,000,000
Government Securities	9,024,777		—		(13,647)		9,011,130
Mutual Funds	392,482		1,575		(476)		393,581
Corporate Bonds	12,952,229		—		(7,230)		12,944,999
Other	188,344		—		—		188,344
Long-Term Investments:
Corporate Bonds	3,022,994		—		(4,274)		3,018,720
Common Stocks	10,897,219		5,079,815		(273,663)		15,703,371
Mutual Funds	29,306,540		5,440,344		(65,547)		34,681,337
Preferred Stock	1,141,458		40,533		(3,000)		1,178,991
Total	$	196,926,043	$	10,562,267	$	(367,837)	$	207,120,473

Schedule of Unrealized Loss on Investments

Unrealized losses on investments as of March 31, 2018, are as follows:

	Aggregate Unrealized Losses		Aggregate Fair Value
Less than one year	$	33,160	$	21,895,327
Greater than one year	—		—
Total	$	33,160	$	21,895,327

Unrealized losses on investments as of December 31, 2017, are as follows: 

	Aggregate Unrealized Losses		Aggregate Fair Value
Less than one year	$	263,655	$	31,223,557
Greater than one year	104,182		285,077
Total	$	367,837	$	31,508,634

Investments Classified by Contractual Maturity Date

Fixed income securities as of March 31, 2018 have contractual maturities as follows:

Due within one year	$	151,895,327
Due between one and five years	—
Due over five years	—
	$	151,895,327