Investments (Tables)

3 Months Ended

Mar. 31, 2016

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		Unrealized		Unrealized		Fair
As of March 31, 2016	Cost		Gains		Losses		Value
U.S. Treasury securities and obligations of U.S. Government	$	74,338	$	231	$	-	$	74,569
Corporate bonds		161,211		956		(1,472)		160,695
Collateralized corporate bank loans		81,062		116		(787)		80,391
Municipal bonds		196,870		2,194		(6,384)		192,680
Mortgage-backed		56,599		387		(563)		56,423
Total debt securities		570,080		3,884		(9,206)		564,758
Total equity securities		27,460		22,998		(1,130)		49,328
Total debt and equity securities	$	597,540	$	26,882	$	(10,336)	$	614,086
As of December 31, 2015
U.S. Treasury securities and obligations of U.S. Government	$	76,323	$	7	$	(61)	$	76,269
Corporate bonds		122,894		637		(1,822)		121,709
Collateralized corporate bank loans		83,434		44		(1,882)		81,596
Municipal bonds		196,446		1,888		(5,966)		192,368
Mortgage-backed		59,532		155		(304)		59,383
Total debt securities		538,629		2,731		(10,035)		531,325
Total equity securities		24,951		23,391		(838)		47,504
Total debt and equity securities	$	563,580	$	26,122	$	(10,873)	$	578,829

Summary of Realized Gain (Loss) on Investments

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

	Three Months Ended March 31,
	2016		2015
U.S. Treasury securities and  obligations of U.S. Government	$	-	$	-
Corporate bonds		80		-
Collateralized corporate bank loans		18		18
Municipal bonds		(24)		(26)
Mortgage-backed		-		187
Equity securities		-		682
Gain on investments		74		861
Other-than-temporary impairments		(301)		(277)
Net realized (losses) gains	$	(227)	$	584

Summary of Gross Unrealized Losses for Investments that have been Continuously in 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, 2016 and December 31, 2015 (in thousands):

	As of March 31, 2016
	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		72,123		(1,472)		-		-		72,123		(1,472)
Collateralized corporate bank loans		45,414		(691)		5,314		(96)		50,728		(787)
Municipal bonds		16,565		(279)		20,798		(6,105)		37,363		(6,384)
Mortgage-backed		29,780		(561)		44		(2)		29,824		(563)
Total debt securities		163,882		(3,003)		26,156		(6,203)		190,038		(9,206)
Total equity securities		2,796		(474)		1,689		(656)		4,485		(1,130)
Total debt and equity securities	$	166,678	$	(3,477)	$	27,845	$	(6,859)	$	194,523	$	(10,336)
	As of December 31, 2015
	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	$	41,428	$	(61)	$	-	$	-	$	41,428	$	(61)
Corporate bonds		96,475		(1,822)		-		-		96,475		(1,822)
Collateralized corporate bank loans		65,868		(1,758)		3,532		(124)		69,400		(1,882)
Municipal bonds		44,525		(488)		25,310		(5,478)		69,835		(5,966)
Mortgage-backed		36,251		(302)		48		(2)		36,299		(304)
Total debt securities		284,547		(4,431)		28,890		(5,604)		313,437		(10,035)
Total equity securities		6,584		(838)		-		-		6,584		(838)
Total debt and equity securities	$	291,131	$	(5,269)	$	28,890	$	(5,604)	$	320,021	$	(10,873)

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

	Amortized		Fair
	Cost		Value
	(in thousands)
Due in one year or less	$	76,399	$	76,378
Due after one year through five years		275,361		274,245
Due after five years through ten years		100,146		96,120
Due after ten years		61,575		61,592
Mortgage-backed		56,599		56,423
	$	570,080	$	564,758