Investments (Tables)

3 Months Ended

Mar. 31, 2021

Investments [Abstract]

Amortized Cost and Estimated Fair Value of Investments in Debt and Equity Securities by Category

The amortized cost and estimated fair value of investments in debt and equity securities by category is as follows (in thousands):

			Gross		Gross
		Amortized Cost/	Unrealized		Unrealized
	Carrying Value		Gains		Losses		Fair Value
As of March 31, 2021
U.S. Treasury securities and obligations of U.S. Government	$	45,088	$	320	$	(1)	$	45,407
Corporate bonds		187,405		4,258		(123)		191,540
Corporate bank loans		60,330		7		(737)		59,600
Municipal bonds		48,027		607		(46)		48,588
Mortgage-backed		3,382		70		(62)		3,390
Total debt securities		344,232		5,262		(969)		348,525
Total equity securities		46,847		8,974		(2,200)		53,621
Total investments	$	391,079	$	14,236	$	(3,169)	$	402,146
				Gross		Gross
		Amortized Cost/		Unrealized		Unrealized
As of December 31, 2020		Carrying Value		Gains		Losses		Fair Value
U.S. Treasury securities and obligations of U.S. Government	$	179,259	$	487	$	—	$	179,746
Corporate bonds		214,666		5,086		(384)		219,368
Corporate bank loans		53,650		3		(871)		52,782
Municipal bonds		49,833		756		(50)		50,539
Mortgage-backed		4,759		114		(29)		4,844
Total debt securities		502,167		6,446		(1,334)		507,279
Total equity securities		26,988		5,648		(3,248)		29,388
Total investments	$	529,155	$	12,094	$	(4,582)	$	536,667

Major Categories of Net Investment (Losses) Gains on Investments

Major categories of net investment gains (losses) on investments are summarized as follows (in thousands):

	Three Months Ended March 31,
	2021		2020
Corporate bonds	$	197	$	55
Corporate bank loans		51		(148)
Municipal bonds		(9)		1,420
Equity securities		1,164		4,309
Gain on investments		1,403		5,636
Unrealized (losses) gains on other investments		—		(2,001)
Unrealized gain (losses) on equity investments		4,376		(32,965)
Investment gains (losses), net	$	5,779	$	(29,330)

Summary of Gross Unrealized Loss Position

The following schedules summarize the gross unrealized losses showing the length of time that investments have been continuously in an unrealized loss position as of March 31, 2021 and December 31, 2020 (in thousands):

	As of March 31, 2021
	12 months or less				Longer than 12 months				Total
			Unrealized				Unrealized				Unrealized
	Fair Value		Losses		Fair Value		Losses		Fair Value		Losses
U.S. Treasury securities and obligations of U.S. Government	$	2,950	$	(1)	$	—	$	—	$	2,950	$	(1)
Corporate bonds		1,819		(5)		3,244		(118)		5,063		(123)
Corporate bank loans		22,011		(104)		25,118		(633)		47,129		(737)
Municipal bonds		2,720		(27)		1,464		(19)		4,184		(46)
Mortgage-backed		368		(57)		13		(5)		381		(62)
Total debt securities		29,868		(194)		29,839		(775)		59,707		(969)
Total equity securities		8,118		(635)		6,538		(1,565)		14,656		(2,200)
Total investments	$	37,986	$	(829)	$	36,377	$	(2,340)	$	74,363	$	(3,169)

	As of December 31, 2020
	12 months or less				Longer than 12 months				Total
			Unrealized				Unrealized				Unrealized
	Fair Value		Losses		Fair Value		Losses		Fair Value		Losses
U.S. Treasury securities and obligations of U.S. Government	$	—	$	—	$	—	$	—	$	—	$	—
Corporate bonds		7,801		(186)		3,556		(198)		11,357		(384)
Corporate bank loans		45,233		(559)		4,144		(312)		49,377		(871)
Municipal bonds		2,859		(33)		1,154		(17)		4,013		(50)
Mortgage-backed		635		(25)		14		(4)		649		(29)
Total debt securities		56,528		(803)		8,868		(531)		65,396		(1,334)
Total equity securities		9,572		(1,610)		1,848		(1,638)		11,420		(3,248)
Total investments	$	66,100	$	(2,413)	$	10,716	$	(2,169)	$	76,816	$	(4,582)

Schedule of Amortized Cost and Estimated Fair Value of Debt Securities by Contractual Maturities

	Amortized Cost		Fair Value
	(in thousands)
Due in one year or less	$	150,383	$	151,762
Due after one year through five years		140,739		143,504
Due after five years through ten years		32,369		32,165
Due after ten years		17,359		17,704
Mortgage-backed		3,382		3,390
	$	344,232	$	348,525