2. Investments

Investments consist of the following:

	April 30,

	2013		2012
	(In thousands)
Short-term investments:
Held-to-maturity securities:
Municipal securities	$	73,241	$	49,263
U.S. government securities		—		27,889

Total short-term investments	$	73,241	$	77,152

Long-term investments:
Held-to-maturity securities:
Municipal securities	$	54,158	$	52,261
Available-for-sale securities:
Auction rate securities		5,687		6,196
Convertible bonds		9,071		—

Total long-term investments	$	68,916	$	58,457

Held-To-Maturity Securities

As of April 30, 2013 the balance of held-to-maturity securities consisted of state and local government municipal securities. As of April 30, 2012 the balance of held-to-maturity securities consisted of state and local government municipal securities and U.S. Treasury bills and notes. Interest earned from these investments is recorded in interest income.

The amortized cost, gross unrealized losses, and estimated fair value of the held-to-maturity investments as of April 30, are as follows (in thousands):

	2013									2012

	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses			Fair Value		Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses			Fair Value
Municipal securities	$	127,399	$	49	$	(23	)	$	127,425	$	101,524	$	48	$	(24	)	$	101,548
U.S. government securities		—		—		—			—		27,889		—		(1	)		27,888

Total held-to-maturity investments	$	127,399	$	49	$	(23	)	$	127,425	$	129,413	$	48	$	(25	)	$	129,436

The amortized cost and fair value of the Company's held-to-maturity securities by contractual maturity at April 30, 2013, are as follows:

	Cost		Fair Value

Due within one year	$	73,241	$	73,258
Due after one year through five years		54,158		54,167

Total	$	127,399	$	127,425

Available-For-Sale Securities
- Auction Rate Securities

As of April 30, 2013 and 2012, the entire balance of available-for-sale auction rate securities consisted of three and four investment grade auction rate municipal bonds, respectively, with maturities ranging from 6 to 21 years. These investments have characteristics similar to short-term investments, because at pre-determined intervals, generally ranging from 30 to 35 days, there is a new auction process at which the interest rates for these securities are reset to current interest rates. At the end of such period, the Company chooses to roll-over its holdings or redeem the investments for cash. A market maker facilitates the redemption of the securities and the underlying issuers are not required to redeem the investment within 365 days. Interest earned from these investments is recorded in interest income.

During the fourth quarter of the fiscal year ended April 30, 2008, the Company began experiencing failed auctions on some of its auction rate securities. A failed auction occurs when a buyer for the securities cannot be obtained and the market maker does not buy the security for its own account. The Company continues to earn interest on the investments that failed to settle at auction, at the maximum contractual rate until the next auction occurs. In the event the Company needs to access funds invested in these auction rate securities, the Company may not be able to liquidate these securities at the fair value recorded on April 30, 2013 until a future auction of these securities is successful or a buyer is found outside of the auction process.

As a result of the failed auctions, the fair values of these securities are estimated utilizing a discounted cash flow analysis as of April 30, 2013 and 2012. The analysis considers, among other items, the collateralization underlying the security investments, the creditworthiness of the counterparty, the timing of expected future cash flows, and the expectation of the next time the security is expected to have a successful auction.

Based on the Company's ability to access its cash and cash equivalents, expected operating cash flows, and other sources of cash, the Company does not anticipate the current lack of liquidity on these investments will affect its ability to operate the business in the ordinary course. The Company believes the current lack of liquidity of these investments is temporary and expects that the securities will be redeemed or refinanced at some point in the future. The Company will continue to monitor the value of its auction rate securities at each reporting period for a possible impairment if a further decline in fair value occurs. The auction rate securities have been in an unrealized loss position for more than 12 months. The Company has the ability and the intent to hold these investments until a recovery of fair value, which may be maturity and as of April 30, 2013, it did not consider these investments to be other-than-temporarily impaired.

The amortized cost, gross unrealized losses, and estimated fair value of the available-for-sale auction rate securities are as follows (in thousands):

	April 30,

	2013			2012
Auction rate securities
Amortized cost	$	6,750		$	7,350
Gross unrealized losses		(1,063	)		(1,154	)

Fair value	$	5,687		$	6,196

The amortized cost and fair value of the Company's auction rate securities by contractual maturity at April 30, 2013 are as follows (in thousands):

	Cost		Fair Value

Due after five through 10 years	$	1,350	$	1,256
Due after 10 years		5,400		4,431

Total	$	6,750	$	5,687

- Convertible Bonds

As of April 30, 2013, the entire balance of available-for-sale convertible bonds consisted of two convertible bonds. The two convertible bonds were issued by CybAero AB ("CybAero"), a publicly traded company in Sweden that develops and manufactures unmanned aerial vehicles. Each bond is in the amount of 10 million Swedish Kronor ("SEK") and is convertible into 1 million CybAero shares at the conversion price of 10 SEK per share. The maturity date of each of the bonds is November 30, 2017 and each bond bears an annual interest rate of 5%.

CybAero can prepay the bonds with three months' notice to the Company and the Company may exercise its conversion rights during such three-month period. If certain conditions are satisfied after November 30, 2015, CybAero can require the Company to convert the two bonds in their entirety into CybAero shares.

The convertible bonds contain an embedded conversion feature which is bifurcated from the bond. The changes in the fair value of the embedded conversion feature are recorded in other income in the income statement. Unrealized gains and losses of the bond are excluded from earnings and reported as a separate component of stockholders' equity, net of deferred income taxes.

On May 14, 2013, CybAero effected a reverse stock split whereby every 10 shares of CybAero were converted into 1 share. All amounts discussed as of April 30, 2013 reflect this reverse stock split.

The amortized cost, gross unrealized gains, gross unrealized losses, and estimated fair value of the available-for-sale convertible bonds are as follows (in thousands):

	April 30,

	2013			2012
Convertible bonds
Amortized cost	$	3,037		$	—
Gross unrealized gains		6,173			—
Gross unrealized losses		(139	)		—

Fair value	$	9,071		$	—

The amortized cost and fair value of the Company's convertible bonds by contractual maturity at April 30, 2013 are as follows (in thousands):

	Cost		Fair Value

Due within five years	$	3,037	$	9,071

Total	$	3,037	$	9,071