Investments (Table Text Block)

6 Months Ended

12 Months Ended

Sep. 30, 2015

Mar. 31, 2015

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	$	91,443	$	3,681	$	–	$	(369)	$	94,755
U.S. government agency mortgage-backed securities		28,050		2,397		(5)		(69)		30,373
Obligations of states and political subdivisions		161,134		10,175		(82)		(607)		170,620
Corporate securities		982,345		33,646		(1,637)		(11,720)		1,002,634
Mortgage-backed securities		19,079		666		–		(46)		19,699
Redeemable preferred stocks		18,055		351		–		(308)		18,098
Common stocks		18,482		6,164		–		(45)		24,601
	$	1,318,588	$	57,080	$	(1,724)	$	(13,164)	$	1,360,780

		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	$	99,722	$	5,658	$	(64)	$	–	$	105,316
U.S. government agency mortgage-backed securities		30,569		2,614		(39)		(3)		33,141
Obligations of states and political subdivisions		165,724		13,052		(298)		(10)		178,468
Corporate securities		885,470		44,426		(2,522)		(2,966)		924,408
Mortgage-backed securities		19,874		806		(1)		–		20,679
Redeemable preferred stocks		18,052		521		(253)		(24)		18,296
Common stocks		17,975		6,719		–		(40)		24,654
	$	1,237,386	$	73,796	$	(3,177)	$	(3,043)	$	1,304,962

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

		September 30, 2015				March 31, 2015
		Amortized Cost		Estimated Market Value		Amortized Cost		Estimated Market Value
		(Unaudited)
		(In thousands)
Due in one year or less	$	53,310	$	54,085	$	36,355	$	37,055
Due after one year through five years		185,138		195,011		198,488		209,404
Due after five years through ten years		502,261		514,431		474,639		492,782
Due after ten years		522,263		534,855		472,003		502,092
		1,262,972		1,298,382		1,181,485		1,241,333
Mortgage backed securities		19,079		19,699		19,874		20,679
Redeemable preferred stocks		18,055		18,098		18,052		18,296
Common stocks		18,482		24,601		17,975		24,654
	$	1,318,588	$	1,360,780	$	1,237,386	$	1,304,962