Investments

Short-term investments consist of high grade municipal and corporate bonds and other debt securities. The Company classifies its marketable securities as available-for-sale based upon management’s determination that the underlying cash invested in these securities is available for operations as necessary.

The following tables provide a summary of marketable investments by type (in thousands):



	September 23, 2012
	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses			Estimated Fair Value
Municipal bonds	$	237,007	$	1,936	$	(24	)	$	238,919
Corporate bonds	142,437		2,573		(7		)	145,003
Certificates of deposit	185,000		—		—			185,000
U.S. agency securities	72,759		515		(2		)	73,272
Non-U.S. government securities	10,214		25		(1		)	10,238
Total	$	647,417	$	5,049	$	(34	)	$	652,432

	June 24, 2012
	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses			Estimated Fair Value
Municipal bonds	$	209,626	$	2,036	$	(58	)	$	211,604
Corporate bonds	144,942		1,848		(123		)	146,667
Certificates of deposit	130,000		—		—			130,000
U.S. agency securities	68,156		450		(7		)	68,599
Non-U.S. government securities	8,746		15		(3		)	8,758
Total	$	561,470	$	4,349	$	(191	)	$	565,628

The following tables present the gross unrealized losses and estimated fair value of the Company's investment securities, aggregated by investment type and length of time that individual investments securities have been in a continuous unrealized loss position (in thousands):



	September 23, 2012
	Less than 12 Months					Greater than 12 Months				Total
	Fair Value		Unrealized Loss			Fair Value		Unrealized Loss		Fair Value		Unrealized Loss
Municipal bonds	$	33,121	$	(24	)	$	—	$	—	$	33,121	$	(24	)
Corporate bonds	15,850		(7		)	—		—		15,850		(7		)
U.S. agency securities	3,013		(2		)	—		—		3,013		(2		)
Non-U.S. government securities	3,037		(1		)	—		—		3,037		(1		)
Total	$	55,021	$	(34	)	$	—	$	—	$	55,021	$	(34	)
Number of securities with an unrealized loss			22					—				22

	June 24, 2012
	Less than 12 Months					Greater than 12 Months				Total
	Fair Value		Unrealized Loss			Fair Value		Unrealized Loss		Fair Value		Unrealized Loss
Municipal bonds	$	30,102	$	(58	)	$	—	$	—	$	30,102	$	(58	)
Corporate bonds	30,550		(123		)	—		—		30,550		(123		)
U.S. agency securities	3,014		(7		)	—		—		3,014		(7		)
Non-U.S. government securities	1,543		(3		)	—		—		1,543		(3		)
Total	$	65,209	$	(191	)	$	—	$	—	$	65,209	$	(191	)
Number of securities with an unrealized loss			33					—				33

The contractual maturities of marketable investments at September 23, 2012 were as follows (in thousands):



	September 23, 2012
	Within One Year		After One, Within Five Years		After Five, Within Ten Years		After Ten Years		Total
Municipal bonds	$	109,450	$	129,469	$	—	$	—	$	238,919
Corporate bonds	40,096		104,907		—		—		145,003
Certificates of deposit	185,000		—		—		—		185,000
U.S. agency securities	29,334		43,938		—		—		73,272
Non-U.S. government securities	4,541		5,697		—		—		10,238
Total	$	368,421	$	284,011	$	—	$	—	$	652,432