Investments (Tables)

3 Months Ended

Mar. 31, 2021

Investments [Abstract]

Investment Securities Stated at Fair Value

Assets or liabilities that have recurring fair value measurements are shown below as of March 31, 2021 and December 31, 2020:

As of March 31, 2021:

			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, 2021		(Level 1)		(Level 2)		(Level 3)
Cash & Cash Equivalents	$	455,940,751	$	455,940,751	$	—	$	—
Short-Term Investments:
Certificate of Deposit	2,519,358		2,519,358		—		—
Corporate Bonds	5,065,020		—		5,065,020		—
Government Securities	6,641,463		—		6,641,463		—
Municipal Bonds	10,192,907		—		10,192,907		—
Other	1,525,366		1,525,366		—		—
Long-Term Investments:
Asset Backed Securities	26,720,719		—		26,720,719		—
Certificate of Deposit	2,613,503		2,613,503		—		—
Corporate Bonds	20,105,773		—		20,105,773		—
Government Securities	12,909,523		—		12,909,523		—
Municipal Bonds	106,540,254		—		106,540,254		—
Total	$	650,774,637	$	462,598,978	$	188,175,659	$	—

As of December 31, 2020:

			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, 2020		(Level 1)		(Level 2)		(Level 3)
Cash & Cash Equivalents	$	423,371,036	$	423,371,036	$	—	$	—
Short-Term Investments:
Certificate of Deposit	1,516,693		1,516,693		—		—
Corporate Bonds	7,155,600		—		7,155,600		—
Government Securities	6,678,450		—		6,678,450		—
Municipal Bonds	10,284,765		—		10,284,765		—
Other	1,528,861		1,528,861		—		—
Long-Term Investments:
Asset-backed Securities	37,924,537		—		37,924,537		—
Certificate of Deposit	3,645,520		3,645,520				—
Corporate Bonds	9,024,035		—		9,024,035		—
Municipal Bonds	107,407,831		—		107,407,831		—
Total	$	608,537,328	$	430,062,110	$	178,475,218	$	—

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, 2021 and December 31, 2020:

As of March 31, 2021:

			Unrealized
	Cost		Gains		Losses		Market Value
Short-Term Investments:
Certificate of Deposit	$	2,502,868	$	17,097	$	(607)	$	2,519,358
Corporate Bonds	5,052,118		12,902		—		5,065,020
Government Securities	6,634,876		6,587		—		6,641,463
Municipal Bonds	10,119,894		73,013		—		10,192,907
Other	1,525,366		—		—		1,525,366
Long-Term Investments:
Asset Backed Securities	27,213,749		69,001		(562,031)		26,720,719
Certificate of Deposit	2,502,813		110,690		—		2,613,503
Corporate Bonds	20,001,918		298,615		(194,760)		20,105,773
Government Securities	13,107,074		—		(197,551)		12,909,523
Municipal Bonds	103,593,419		3,579,244		(632,409)		106,540,254
Total	$	192,254,095	$	4,167,149	$	(1,587,358)	$	194,833,886

As of December 31, 2020:    

			Unrealized
	Cost		Gains		Losses		Market Value
Short-Term Investments:
Certificate of Deposit	$	1,502,187	$	14,506	$	—	$	1,516,693
Corporate Bonds	7,084,638		70,962		—		7,155,600
Government Securities	6,635,132		43,318		—		6,678,450
Municipal Bonds	10,160,376		124,389		—		10,284,765
Other	1,528,861		—		—		1,528,861
Long-Term Investments:
Asset-backed Securities	37,681,113		800,802		(557,378)		37,924,537
Certificate of Deposit	3,503,898		141,622		—		3,645,520
Corporate Bonds	8,595,020		429,015		—		9,024,035
Municipal Bonds	100,776,325		6,635,428		(3,922)		107,407,831
Total	$	177,467,550	$	8,260,042	$	(561,300)	$	185,166,292

Schedule of Unrealized Loss on Investments

Unrealized losses on investments as of March 31, 2021, are as follows:

	Aggregate Unrealized Losses		Aggregate Fair Value of Investments
Loss duration of less than one year	$	1,176,276	$	56,463,167
Loss duration of greater than one year	411,082		1,958,502
Total	$	1,587,358	$	58,421,669

Unrealized losses on investments as of December 31, 2020, are as follows: 

	Aggregate Unrealized Losses		Aggregate Fair Value of Investments
Loss duration of less than one year	$	561,300	$	12,317,187
Loss duration of greater than one year	—		—
Total	$	561,300	$	12,317,187

Investments Classified by Contractual Maturity Date

Fixed income securities as of March 31, 2021 have contractual maturities as follows:

Due within one year	$	24,418,748
Due between one and five years	39,844,725
Due over five years	129,045,047
	$	193,308,520