Investments (Table Text Block)

9 Months Ended

12 Months Ended

Dec. 31, 2015

Mar. 31, 2015

Investments Debt Equity Securities [Abstract]

Available-for-Sale Investments

Available-for-sale investments at December 31, 2015 were as follows:

		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	$	76,429	$	5,155	$	–	$	–	$	81,584
U.S. government agency mortgage-backed securities		22,875		1,959		(5)		–		24,829
Obligations of states and political subdivisions		168,889		12,156		(58)		(264)		180,723
Corporate securities		1,073,111		36,145		(2,259)		(16,496)		1,090,501
Mortgage-backed securities		43,076		1,014		–		–		44,090
Redeemable preferred stocks		18,056		312		–		(198)		18,170
Common stocks		18,492		5,848		(10)		(230)		24,100
	$	1,420,928	$	62,589	$	(2,332)	$	(17,188)	$	1,463,997

Available-for-sale investments at March 31, 2015 were as follows:

		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

The adjusted cost and estimated market value of available-for-sale investments by contractual maturity, were as follows:

		December 31, 2015				March 31, 2015
		Amortized Cost		Estimated Market Value		Amortized Cost		Estimated Market Value
		(Unaudited)
		(In thousands)
Due in one year or less	$	51,630	$	52,331	$	36,355	$	37,055
Due after one year through five years		206,310		216,005		198,488		209,404
Due after five years through ten years		515,059		526,263		474,639		492,782
Due after ten years		568,305		583,038		472,003		502,092
		1,341,304		1,377,637		1,181,485		1,241,333
Mortgage backed securities		43,076		44,090		19,874		20,679
Redeemable preferred stocks		18,056		18,170		18,052		18,296
Common stocks		18,492		24,100		17,975		24,654
	$	1,420,928	$	1,463,997	$	1,237,386	$	1,304,962