4. 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, 2011, January 31, 2011 and October 31, 2010 were as follows:


	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
Auction rate securities		23,650		—		(2,694	)		20,956
Certificate of deposit		6,234		1		(1	)		6,234

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

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

As of January 31, 2011
Short-term Investments:
Municipal and pre-refunded municipal bonds	$	42,996	$	48	$	(9	)	$	43,035
Federal government agencies		40,842		80		—			40,922
Treasury bills		7,004		4		—			7,008
FDIC insured corporate bonds		23,489		66		—			23,555
Variable rate demand notes		1,900		—		—			1,900

		116,231		198		(9	)		116,420

Long-term Investments:
Corporate bonds		137,540		173		(154	)		137,559
Municipal and pre-refunded municipal bonds		143,711		216		(558	)		143,369
Auction rate securities		33,250		—		(3,788	)		29,462
Federal government agencies		18,225		30		(2	)		18,253
Treasury bills		23,311		34		—			23,345

		356,037		453		(4,502	)		351,988

	$	472,268	$	651	$	(4,511	)	$	468,408

As of October 31, 2010
Short-term Investments:
Municipal and pre-refunded municipal bonds	$	63,043	$	99	$	(5	)	$	63,137
Federal government agencies		73,592		180		—			73,772
Treasury bills		39,550		15		—			39,565
FDIC insured corporate bonds		41,528		151		—			41,679
Variable rate demand notes		31,925		—		—			31,925

		249,638		445		(5	)		250,078

Long-term Investments:
Municipal and pre-refunded municipal bonds		153,409		732		(97	)		154,044
Auction rate securities		33,850		—		(3,707	)		30,143
Federal government agencies		2,004		11		—			2,015

		189,263		743		(3,804	)		186,202

	$	438,901	$	1,188	$	(3,809	)	$	436,280

Proceeds from the sale and maturities of available-for-sale securities were $384,594 and $396,762 for the nine months ended October 31, 2011 and 2010, 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. The Company included in other income, net realized gains of $1 and net realized losses of $19 for the three and nine months ended October 31, 2010, 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. Amortization of discounts and premiums, net, resulted in charges of $2,223 and $6,552 for the three and nine months ended October 31, 2010, respectively.

As of October 31, 2011, the par value of the Company's auction rate securities ("ARS") was $23,650 and the estimated fair value was $20,956. The Company's ARS portfolio consists of "A" or better rated ARS that represent interests in municipal and student loan related collateralized debt obligations, all of which are guaranteed by either government agencies and/or insured by private insurance agencies at 97% or greater of par value. 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 have the intent to sell the underlying securities prior to their full 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.