Investments (Tables)

3 Months Ended

Mar. 31, 2019

Investments [Abstract]

Investment Securities Stated at Fair Value

Assets or liabilities that have recurring fair value measurements are shown below as of March 31, 2019 and December 31, 2018:

As of March 31, 2019

			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, 2019		(Level 1)		(Level 2)		(Level 3)
Cash & Cash Equivalents	$	221,688,575	$	221,688,575	$	—	$	—
Short-Term Investments:
Certificate of Deposit	150,299,384		150,299,384		—		—
Government Securities	21,109,868		—		21,109,868		—
Corporate Bonds	5,982,688		—		5,982,688		—
Other	2,921,282		2,921,282		—		—
Long-Term Investments:
Corporate Bonds	66,610,295		—		66,610,295		—
Municipal Bonds	21,283,707		—		21,283,707		—
Government Securities	34,534,506		—		34,534,506		—
Total	$	524,430,305	$	374,909,241	$	149,521,064	$	—

As of December 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	December 31, 2018		(Level 1)		(Level 2)		(Level 3)
Cash & Cash Equivalents	$	217,025,278	$	217,025,278	$	—	$	—
Short-Term Investments:
Certificate of Deposit	150,299,384		150,299,384		—		—
Government Securities	9,176,227		—		9,176,227		—
Corporate Bonds	6,967,700		—		6,967,700		—
Other	2,219,688		2,219,688		—		—
Long-Term Investments:
Corporate Bonds	60,369,930		—		60,369,930		—
Municipal Bonds	18,025,432		—		18,025,432		—
Government Securities	56,483,720		—		56,483,720		—
Total	$	520,567,359	$	369,544,350	$	151,023,009	$	—

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

The amortized cost, unrealized gains and losses, and market value of investment securities are shown as of March 31, 2019 and December 31, 2018:

As of March 31, 2019

			Unrealized
	Cost		Gains		Losses		Market Value
Short-Term Investments:
Certificate of Deposit	$	150,299,384	$	—	$	—	$	150,299,384
Government Securities	21,101,631		9,901		(1,664)		21,109,868
Corporate Bonds	5,979,056		4,095		(463)		5,982,688
Other	2,921,282		—		—		2,921,282
Long-Term Investments:
Corporate Bonds	66,172,642		504,809		(67,156)		66,610,295
Municipal Bonds	20,851,133		432,574		—		21,283,707
Government Securities	34,316,447		218,059		$	—	34,534,506
Total	$	301,641,575	$	1,169,438	$	(69,283)	$	302,741,730

As of December 31, 2018 

			Unrealized
	Cost		Gains		Losses		Market Value
Short-Term Investments:
Certificate of Deposit	$	150,299,384	$	—	$	—	$	150,299,384
Government Securities	9,186,586		—		(10,359)		9,176,227
Corporate Bonds	6,981,305		—		(13,605)		6,967,700
Other	2,219,688		—		—		2,219,688
Long-Term Investments:
Corporate Bonds	60,659,498		50,340		(339,908)		60,369,930
Municipal Bonds	17,840,518		184,914		—		18,025,432
Government Securities	56,280,552		205,553		(2,385)		56,483,720
Total	$	303,467,531	$	440,807	$	(366,257)	$	303,542,081

Schedule of Unrealized Loss on Investments

Unrealized losses on investments as of March 31, 2019, are as follows:

	Aggregate Unrealized Losses		Aggregate Fair Value
Less than one year	$	69,283	$	20,786,455
Greater than one year	—		—
Total	$	69,283	$	20,786,455

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

	Aggregate Unrealized Losses		Aggregate Fair Value
Less than one year	$	365,824	$	68,722,980
Greater than one year	433		3,000,000
Total	$	366,257	$	71,722,980

Investments Classified by Contractual Maturity Date

Fixed income securities as of March 31, 2019 have contractual maturities as follows:

Due within one year	$	177,391,940
Due between one and five years	111,377,100
Due over five years	11,051,408
	$	299,820,448