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
		Cost /	Unrealized		Unrealized
	Amortized Cost		Gains		Losses		Fair Value
As of September 30, 2020
U.S. Treasury securities and obligations of U.S. Government	$	60,332	$	671	$	(2)	$	61,001
Corporate bonds		235,469		5,291		(1,281)		239,479
Collateralized corporate bank loans		57,559		-		(2,225)		55,334
Municipal bonds		54,837		852		(51)		55,638
Mortgage-backed		6,000		122		(5)		6,117
Total debt securities		414,197		6,936		(3,564)		417,569
Total equity securities		25,735		2,989		(5,352)		23,372
Total other investments		3,763		—		(3,729)		34
Total investments	$	443,695	$	9,925	$	(12,645)	$	440,975

As of December 31, 2019
U.S. Treasury securities and obligations of U.S. Government	$	66,441	$	162	$	(3)	$	66,600
Corporate bonds		297,601		3,387		(163)		300,825
Collateralized corporate bank loans		115,669		556		(468)		115,757
Municipal bonds		81,787		1,531		(48)		83,270
Mortgage-backed		8,000		46		(219)		7,827
Total debt securities		569,498		5,682		(901)		574,279
Total equity securities		71,895		35,028		(7,708)		99,215
Total other investments		3,763		—		(1,594)		2,169
Total investments	$	645,156	$	40,710	$	(10,203)	$	675,663

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 September 30, 2020 and December 31, 2019 (in thousands):


	As of September 30, 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	$	18,091	$	(2)	$	—	$	—	$	18,091	$	(2)
Corporate bonds		8,982		(1,035)		4,071		(246)		13,053		(1,281)
Collateralized corporate bank loans		49,558		(1,571)		5,638		(654)		55,196		(2,225)
Municipal bonds		2,550		(33)		1,379		(18)		3,929		(51)
Mortgage-backed		—		—		14		(5)		14		(5)
Total debt securities		79,181		(2,641)		11,102		(923)		90,283		(3,564)
Total equity securities		10,265		(4,187)		1,935		(1,165)		12,200		(5,352)
Total other investments		—		—		34		(3,729)		34		(3,729)
Total investments	$	89,446	$	(6,828)	$	13,071	$	(5,817)	$	102,517	$	(12,645)


	As of December 31, 2019
	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	$	—	$	—	$	5,513	$	(3)	$	5,513	$	(3)
Corporate bonds		27,268		(144)		1,150		(19)		28,418		(163)
Collateralized corporate bank loans		9,000		(41)		10,228		(427)		19,228		(468)
Municipal bonds		4,808		(29)		1,618		(19)		6,426		(48)
Mortgage-backed		1,712		(101)		562		(118)		2,274		(219)
Total debt securities		42,788		(315)		19,071		(586)		61,859		(901)
Total equity securities		10,905		(2,363)		6,093		(5,345)		16,998		(7,708)
Total other investments		—		—		2,169		(1,594)		2,169		(1,594)
Total investments	$	53,693	$	(2,678)	$	27,333	$	(7,525)	$	81,026	$	(10,203)

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

The amortized cost and estimated fair value of debt securities at September 30, 2020 by contractual maturity are as follows. Expected maturities may differ from contractual maturities because certain borrowers may have the right to call or prepay obligations with or without penalties.


	Amortized Cost		Fair Value

	(in thousands)
Due in one year or less	$	113,961	$	115,144
Due after one year through five years		248,003		250,693
Due after five years through ten years		32,766		31,560
Due after ten years		13,467		14,055
Mortgage-backed		6,000		6,117
	$	414,197	$	417,569