Marketable Securities (Tables)

3 Months Ended

12 Months Ended

Mar. 31, 2021

Dec. 31, 2020

Marketable Securities

Summary of amortized cost, gross unrealized gains and losses, and estimated fair values of the Company's investments in fixed maturity debt securities

	March 31, 2021
	Amortized		Gross		Gross
	Cost/		Unrealized		Unrealized
	Cost Basis		Gains		Losses		Fair Value
U.S. Treasuries	$	181	$	2	$	—	$	183
Corporate bonds		63,197		2		(111)		63,088
Municipal bonds		24,003		5		(14)		23,994
Commercial paper		130,659		—		—		130,659
Total Fixed Maturity Debt Securities	$	218,040	$	9	$	(125)	$	217,924

	December 31, 2020
	Amortized		Gross		Gross
	Cost/		Unrealized		Unrealized
	Cost Basis		Gains		Losses		Fair Value
U.S. Treasuries	$	240	$	6	$	—	$	246
Corporate bonds		261		5		(1)		265
U.S. states, territories and political subdivisions		141		5		—		146
Total Fixed Maturity Debt Securities	$	642	$	16	$	(1)	$	657

	Amortized		Gross		Gross		Estimated
	Cost		Unrealized Gains		Unrealized Losses		Fair Value
Fixed Maturity Debt Securities
U.S. Treasuries	$	240	$	6	$	—	$	246
Corporates		261		5		(1)		265
U.S. states, territories, and political subdivisions		141		5		—		146
Total Fixed Maturity Debt Securities	$	642	$	16	$	(1)	$	657

Summary of amortized cost and estimated fair value of the Company's fixed maturity debt securities

The amortized cost and fair value of the Company’s fixed maturity debt securities as of March 31, 2021 by contractual maturity are shown below. Expected maturities may differ from contractual maturities because issuers may have the right to call or prepay obligations with or without call or prepayment penalties.

	Amortized Cost		Fair Value
Due in one year or less	$	173,174	$	173,145
Due after one year through five years		44,540		44,457
Due after five years through ten years		326		322
Total	$	218,040	$	217,924

	Amortized		Estimated
	Cost		Fair Value
Due in one year or less	$	77	$	78
Due after one year through five years		379		388
Due after five years through ten years		186		191
Total	$	642	$	657

Summary of gross unrealized losses in fixed maturity debt securities

			March 31, 2021
	Less Than 12 Months				12 Months or More				Total
	Estimated		Unrealized		Estimated		Unrealized		Estimated		Unrealized
	Fair Value		Losses		Fair Value		Losses		Fair Value		Losses
Corporate bonds	$	23,226	$	(31)	$	39,736	$	(80)	$	62,962	$	(111)
Municipal bonds		18,286		(11)		1,135		(3)		19,421		(14)
Total Fixed Maturity Debt Securities	$	41,512	$	(42)	$	40,871	$	(83)	$	82,533	$	(125)

			December 31, 2020
	Less Than 12 Months				12 Months or More				Total
	Estimated		Unrealized		Estimated		Unrealized		Estimated		Unrealized
	Fair Value		Losses		Fair Value		Losses		Fair Value		Losses
Corporate bonds	$	39	$	(1)	$	—	$	—	$	39	$	(1)
Total Fixed Maturity Debt Securities	$	39	$	(1)	$	—	$	—	$	39	$	(1)

	Less Than 12 Months				12 Months or more				Total
		Estimated Fair Value		Unrealized Losses		Estimated Fair Value		Unrealized Losses		Estimated Fair Value		Unrealized Losses
Fixed maturity debt securities:
Corporate Bonds	$	39	$	(1)	$	—	$	—	$	39	$	(1)
Total Fixed Maturity Debt Securities	$	39	$	(1)	$	—	$	—	$	39	$	(1)

Summary of cost and estimated fair values of the Company's investments in equity securities

	March 31, 2021
			Estimated
	Cost		Fair Value
Equity securities	$	433	$	500

	December 31, 2020
			Estimated
	Cost		Fair Value
Equity securities	$	335	$	375

			Estimated
	Cost		Fair Value
Equity securities	$	335	$	375

Summary of proceeds from sales and maturities, gross realized gains, gross realized losses, and net realized gains (losses) from sales and maturities of fixed maturity debt securities

	March 31, 2021
			Gross		Gross		Net
			Realized		Realized		Realized
	Proceeds		Gains		Losses		Losses
Fixed maturity debt securities	$	59	$	—	$	—	$	—
Equity securities		—		—		—		—
Total Marketable Securities	$	59	$	—	$	—	$	—

	March 31, 2020
			Gross		Gross		Net
			Realized		Realized		Realized
	Proceeds		Gains		Losses		Losses
Fixed maturity debt securities	$	18	$	—	$	(3)	$	(3)
Equity securities		—		—		—		—
Total Marketable Securities	$	18	$	1	$	(3)	$	(3)

			Gross		Gross		Net
	Proceeds		Realized Gains		Realized Losses		Realized (Losses)
Fixed maturity debt securities	$	18	$	—	$	—	$	—
Equity securities		50		1		(2)		(1)
Total Marketable Securities	$	68	$	1	$	(2)	$	(1)