Expected maturities may differ from contractual maturities as borrowers may have the right to call or prepay obligations with or without call or prepayment penalties.

We deposit bonds with insurance regulatory authorities to meet statutory requirements. The adjusted cost of bonds on deposit with insurance regulatory authorities was $17.6 million and $16.4 million at June 30, 2015 and March 31, 2015, respectively.

Available-for-Sale Investments

Available-for-sale investments at June 30, 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	$	88,561	$	5,796	$	–	$	(33)	$	94,324
U.S. government agency mortgage-backed securities		29,224		2,712		–		(2)		31,934
Obligations of states and political subdivisions		162,859		14,467		(34)		(87)		177,205
Corporate securities		917,476		52,995		(1,489)		(1,867)		967,115
Mortgage-backed securities		19,259		994		(1)		–		20,252
Redeemable preferred stocks		18,053		591		(54)		(38)		18,552
Common stocks		18,143		6,786		–		(112)		24,817
	$	1,253,575	$	84,341	$	(1,578)	$	(2,139)	$	1,334,199

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

The available-for-sale tables include gross unrealized losses that are not deemed to be other-than-temporarily impaired, aggregated by investment category and length of time that individual securities have been in a continuous unrealized loss position.

We sold available-for-sale securities with a fair value of $29.7 million during the first quarter of fiscal 2016. The gross realized gains on these sales totaled $1.2 million. There were no gross realized losses on these sales.

The unrealized losses of more than twelve months in the available-for-sale tables are considered temporary declines. We track each investment with an unrealized loss and evaluate them on an individual basis for other-than-temporary impairments including obtaining corroborating opinions from third party sources, performing trend analysis and reviewing management’s future plans. Certain of these investments may have declines determined by management to be other-than-temporary and we recognize these write-downs, if any, through earnings. There were no write downs in the first quarter of fiscal 2016 or 2015.

The investment portfolio primarily consists of corporate securities and U.S. government securities. We believe we monitor our investments as appropriate. Our methodology of assessing other-than-temporary impairments is based on security-specific analysis as of the balance sheet date and considers various factors including the length of time to maturity, the extent to which the fair value has been less than the cost, the financial condition and the near-term prospects of the issuer, and whether the debtor is current on its contractually obligated interest and principal payments. Nothing has come to management’s attention that would lead to the belief that each issuer would not have the ability to meet the remaining contractual obligations of the security, including payment at maturity. We have the ability and intent not to sell our fixed maturity and common stock investments for a period of time sufficient to allow us to recover our costs.

The portion of other-than-temporary impairment related to a credit loss is recognized in earnings. The significant inputs utilized in the evaluation of mortgage backed securities credit losses include ratings, delinquency rates, and prepayment activity. The significant inputs utilized in the evaluation of asset backed securities credit losses include the time frame for principal recovery and the subordination and value of the underlying collateral.

There were no credit losses recognized in earnings for which a portion of an other-than-temporary impairment was recognized in accumulated other comprehensive income (loss) for the first quarter of fiscal 2016.

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

		June 30, 2015				March 31, 2015
		Amortized Cost		Estimated Market Value		Amortized Cost		Estimated Market Value
		(Unaudited)
		(In thousands)
Due in one year or less	$	52,734	$	53,626	$	36,355	$	37,055
Due after one year through five years		182,786		194,033		198,488		209,404
Due after five years through ten years		494,677		519,766		474,639		492,782
Due after ten years		467,923		503,153		472,003		502,092
		1,198,120		1,270,578		1,181,485		1,241,333

Mortgage backed securities		19,259		20,252		19,874		20,679
Redeemable preferred stocks		18,053		18,552		18,052		18,296
Equity securities		18,143		24,817		17,975		24,654
	$	1,253,575	$	1,334,199	$	1,237,386	$	1,304,962