Investments (Table Text Block)

6 Months Ended

Sep. 30, 2017

Investments Debt Equity Securities [Abstract]

Available-for-Sale Investments

Available-for-sale investments at September 30, 2017 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	$	123,503	$	3,468	$	–	$	(1,176)	$	125,795
U.S. government agency mortgage-backed securities		26,812		1,355		(2)		(2)		28,163
Obligations of states and political subdivisions		174,665		10,626		(10)		(223)		185,058
Corporate securities		1,332,938		48,148		(3,786)		(3,631)		1,373,669
Mortgage-backed securities		89,858		1,958		–		–		91,816
Redeemable preferred stocks		13,789		539		–		(25)		14,303
Common stocks		15,732		9,242		(10)		–		24,964
	$	1,777,297	$	75,336	$	(3,808)	$	(5,057)	$	1,843,768

Available-for-sale investments at March 31, 2017 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	$	123,474	$	2,892	$	–	$	(1,675)	$	124,691
U.S. government agency mortgage-backed securities		27,908		1,070		(6)		(377)		28,595
Obligations of states and political subdivisions		159,417		9,466		(23)		(424)		168,436
Corporate securities		1,263,703		32,901		(5,731)		(13,837)		1,277,036
Mortgage-backed securities		26,577		515		–		(5)		27,087
Redeemable preferred stocks		13,789		168		–		(468)		13,489
Common stocks		15,732		8,728		(10)		(16)		24,434
	$	1,630,600	$	55,740	$	(5,770)	$	(16,802)	$	1,663,768

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

		September 30, 2017				March 31, 2017
		Amortized Cost		Estimated Market Value		Amortized Cost		Estimated Market Value
		(Unaudited)
		(In thousands)
Due in one year or less	$	40,057	$	40,428	$	35,399	$	35,795
Due after one year through five years		366,506		377,028		324,286		333,016
Due after five years through ten years		609,614		628,689		598,232		607,184
Due after ten years		641,741		666,540		616,585		622,763
		1,657,918		1,712,685		1,574,502		1,598,758
Mortgage backed securities		89,858		91,816		26,577		27,087
Redeemable preferred stocks		13,789		14,303		13,789		13,489
Common stocks		15,732		24,964		15,732		24,434
	$	1,777,297	$	1,843,768	$	1,630,600	$	1,663,768