Investments (Table Text Block)

3 Months Ended

Jun. 30, 2019

Mar. 31, 2019

Investments Debt Equity Securities [Abstract]

Available-for-Sale Investments

		Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses More than 12 Months		Gross Unrealized Losses Less than 12 Months		Estimated Market Value
		(Unaudited)
		(In thousands)
U.S. treasury securities and government obligations	$	135,055	$	3,709	$	(913)	$	(24)	$	137,827
U.S. government agency mortgage-backed securities		41,359		442		(95)		(35)		41,671
Obligations of states and political subdivisions		301,255		13,579		(198)		0		314,636
Corporate securities		1,639,004		36,966		(9,868)		(1,350)		1,664,752
Mortgage-backed securities		147,102		2,834		(127)		(6)		149,803
Redeemable preferred stocks		1,493		57		0		0		1,550
	$	2,265,268	$	57,587	$	(11,201)	$	(1,415)	$	2,310,239

		Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses More than 12 Months		Gross Unrealized Losses Less than 12 Months		Estimated Market Value
		(In thousands)
U.S. treasury securities and government obligations	$	136,010	$	2,409	$	(2,104)	$	(447)	$	135,868
U.S. government agency mortgage-backed securities		31,101		433		(146)		(19)		31,369
Obligations of states and political subdivisions		298,955		8,079		(233)		(905)		305,896
Corporate securities		1,613,199		14,777		(14,257)		(24,986)		1,588,733
Mortgage-backed securities		148,203		880		(285)		(903)		147,895
Redeemable preferred stocks		1,493		20		0		(45)		1,468
	$	2,228,961	$	26,598	$	(17,025)	$	(27,305)	$	2,211,229

Adjusted Cost and Estimated Market Value of Available-for-sale Investments

		June 30, 2019				March 31, 2019
		Amortized Cost		Estimated Market Value		Amortized Cost		Estimated Market Value
		(Unaudited)
		(In thousands)
Due in one year or less	$	80,244	$	80,481	$	71,987	$	71,954
Due after one year through five years		553,626		562,599		541,195		540,658
Due after five years through ten years		646,677		660,403		621,031		614,485
Due after ten years		836,126		855,403		845,052		834,769
		2,116,673		2,158,886		2,079,265		2,061,866
Mortgage-backed securities		147,102		149,803		148,203		147,895
Redeemable preferred stocks		1,493		1,550		1,493		1,468
	$	2,265,268	$	2,310,239	$	2,228,961	$	2,211,229

Available for sale equity investments

		June 30, 2019				March 31, 2019
		Amortized Cost		Estimated Market Value		Amortized Cost		Estimated Market Value
		(Unaudited)
		(In thousands)
Common stocks	$	10,123	$	19,035	$	10,123	$	17,379
Non-redeemable preferred stocks		7,451		7,311		7,451		6,789
	$	17,574	$	26,346	$	17,574	$	24,168