3. Marketable Securities

During all periods presented, marketable securities are classified as available-for-sale. The amortized cost, gross unrealized gains (losses) and fair value of available-for-sale securities by major security type and class of security as of October 31, 2012, January 31, 2012 and October 31, 2011 were as follows:


	Amortized Cost		Unrealized Gains		Unrealized (Losses)			Fair Value
As of October 31, 2012
Short-term Investments:
Corporate bonds	$	64,975	$	89	$	(7	)	$	65,057
Municipal and pre-refunded municipal bonds		29,937		98		(6	)		30,029
Certificate of deposit		28,676		28		—			28,704
Treasury bills		10,582		4		—			10,586
Commercial paper		8,178		11		—			8,189
Federal government agencies		3,500		—		—			3,500

		145,848		230		(13	)		146,065

Long-term Investments:
Corporate bonds		46,507		155		(57	)		46,605
Municipal and pre-refunded municipal bonds		21,456		47		(27	)		21,476
Certificate of deposit		1,925		1		—			1,926
Treasury bills		18,211		7		(1	)		18,217
Federal government agencies		1,211		2		—			1,213
Auction rate securities		4,925		—		(595	)		4,330

		94,235		212		(680	)		93,767

	$	240,083	$	442	$	(693	)	$	239,832


As of January 31, 2012
Short-term Investments:
Corporate bonds	$	34,899	$	7	$	(28	)	$	34,878
Municipal and pre-refunded municipal bonds		41,519		135		(10	)		41,644
Certificate of deposit		5,225		—		—			5,225
Commercial paper		3,580		12		—			3,592
Federal government agencies		4,513		2		—			4,515

		89,736		156		(38	)		89,854

Long-term Investments:
Corporate bonds		60,852		277		(72	)		61,057
Municipal and pre-refunded municipal bonds		18,410		186		(6	)		18,590
Certificate of deposit		6,970		—		(1	)		6,969
Treasury bills		14,982		6		—			14,988
Federal government agencies		5,111		2		(1	)		5,112
Auction rate securities		22,975		—		(2,778	)		20,197

		129,300		471		(2,858	)		126,913

	$	219,036	$	627	$	(2,896	)	$	216,767


	Amortized Cost		Unrealized Gains		Unrealized (Losses)			Fair Value
As of October 31, 2011
Short-term Investments:
Corporate bonds	$	15,846	$	1	$	(67	)	$	15,780
Municipal and pre-refunded municipal bonds		28,129		25		(21	)		28,133
Certificate of deposit		735		—		—			735
Federal government agencies		2,000		1		—			2,001

		46,710		27		(88	)		46,649

Long-term Investments:
Corporate bonds		65,626		261		(260	)		65,627
Municipal and pre-refunded municipal bonds		36,041		311		(23	)		36,329
Certificates of deposit		6,234		1		(1	)		6,234
Auction rate securities		23,650		—		(2,694	)		20,956

		131,551		573		(2,978	)		129,146

	$	178,261	$	600	$	(3,066	)	$	175,795

Proceeds from the sale and maturities of available-for-sale securities were $175,991 and $384,594 for the nine months ended October 31, 2012 and 2011, respectively. The Company included in other income, net, realized gains of $36 and $249 for the three and nine months ended October 31, 2012, respectively. The Company included in other income, net, realized gains of $1,064 and $1,115 for the three and nine months ended October 31, 2011, respectively. Amortization of discounts and premiums, net, resulted in charges of $1,179 and $3,657 for the three and nine months ended October 31, 2012, respectively. Amortization of discounts and premiums, net, resulted in charges of $1,776 and $6,105 for the three and nine months ended October 31, 2011, respectively.

As of October 31, 2012, the par value of the Company’s Auction Rate Securities (“ARS”) was $4,925 and the estimated fair value was $4,330. The Company’s ARS portfolio consists of “A” or better rated ARS that represent interests in municipal obligations. To date, the Company has collected all interest payable on outstanding ARS when due and has not been informed by the issuers that accrued interest payments are currently at risk. The Company does not intend to sell the underlying securities prior to their recovery and the Company believes it is not likely that it will be required to sell the underlying securities prior to their anticipated recovery of full amortized cost.