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. This is based upon management’s determination that the underlying cash invested in these securities is available for operations as necessary.

The following table provides a summary of marketable investments by type (in thousands):



	March 25, 2012
	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses			Estimated Fair Value
Municipal bonds	$	202,208	$	2,377	$	(143	)	$	204,442
Corporate bonds	179,893		1,912		(88		)	181,717
Certificates of deposit	65,000		—		—			65,000
U.S. agency securities	64,283		486		(2		)	64,767
Non-U.S. government securities	3,112		—		(1		)	3,111
Total	$	514,496	$	4,775	$	(234	)	$	519,037

	June 26, 2011
	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses			Estimated Fair Value
Municipal bonds	$	391,465	$	3,943	$	(10	)	$	395,398
Corporate bonds	207,241		2,312		(115		)	209,438
Certificates of deposit	10,003		12		—			10,015
Municipal variable rate demand notes	295		—		—			295
Commercial paper	4,999		—		—			4,999
U.S. agency securities	67,244		807		(2		)	68,049
Non-U.S. government securities	6,986		19		—			7,005
Total	$	688,233	$	7,093	$	(127	)	$	695,199

The following table presents 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):



	March 25, 2012
	Less than 12 Months					Greater than 12 Months				Total
	Fair Value		Unrealized Loss			Fair Value		Unrealized Loss		Fair Value		Unrealized Loss
Municipal bonds	$	21,888	$	(143	)	$	—	$	—	$	21,888	$	(143	)
Corporate bonds	25,936		(88		)	—		—		25,936		(88		)
U.S. agency securities	2,997		(2		)	—		—		2,997		(2		)
Non-U.S. government securities	3,111		(1		)	—		—		3,111		(1		)
Total	$	53,932	$	(234	)	$	—	$	—	$	53,932	$	(234	)
Number of securities with an unrealized loss			26					—				26

	June 26, 2011
	Less than 12 Months					Greater than 12 Months				Total
	Fair Value		Unrealized Loss			Fair Value		Unrealized Loss		Fair Value		Unrealized Loss
Municipal bonds	$	14,348	$	(10	)	$	—	$	—	$	14,348	$	(10	)
Corporate bonds	20,484		(115		)	—		—		20,484		(115		)
U.S. agency securities	6,518		(2		)	—		—		6,518		(2		)
Total	$	41,350	$	(127	)	$	—	$	—	$	41,350	$	(127	)
Number of securities with an unrealized loss			20					—				20

The contractual maturities of marketable investments at March 25, 2012 were as follows (in thousands):



	March 25, 2012
	Within One Year		After One, Within Five Years		After Five, Within Ten Years		After Ten Years		Total
Municipal bonds	$	86,060	$	118,382	$	—	$	—	$	204,442
Corporate bonds	80,333		101,384		—		—		181,717
Certificates of deposit	65,000		—		—		—		65,000
U.S. agency securities	21,802		42,965		—		—		64,767
Non-U.S. government securities	1,010		2,101		—		—		3,111
Total	$	254,205	$	264,832	$	—	$	—	$	519,037