Investments

We invest in pre-funded municipal bonds which are generally secured by escrowed-to-maturity U.S. Treasury notes. Municipal bonds represent debt obligations issued by states, cities, counties and other governmental entities, which earn interest that is exempt from federal income taxes. Additionally, we invest in certificates of deposit issued by financial institutions and corporate bonds from large cap industrial and selected financial companies with a minimum credit rating of A. We have the ability and intent to hold our investments until maturity and therefore classify these investments as held-to-maturity and report them at amortized cost.

Amortized cost and fair value for investments classified as held-to-maturity at June 30, 2013 were as follows:



								Estimated
	Amortized		Gross Unrealized					Fair Market
	Cost		Gains		Losses			Value
Due in less than 1 year:
Municipal bonds	$	27,085	$	11	$	—		$	27,096
Corporate bonds	16,239		1		(23		)	16,217
Certificates of deposit	6,093		—		—			6,093
Due in 1 - 2 years:
Municipal bonds	12,008		6		(4		)	12,010
Corporate bonds	628		—		(1		)	627
Certificates of deposit	1,476		—		—			1,476
	$	63,529	$	18	$	(28	)	$	63,519

Amortized cost and fair value for investments classified as held-to-maturity at September 30, 2012 were as follows:



								Estimated
	Amortized		Gross Unrealized					Fair Market
	Cost		Gains		Losses			Value
Due in less than 1 year:
Municipal bonds	$	23,402	$	2	$	(8	)	$	23,396
Corporate bonds	18,210		8		(3		)	18,215
Certificates of deposit	9,843		3		—			9,846
Due in 1 - 2 years:
Municipal bonds	170		—		—			170
Corporate bonds	—		—		—			—
Certificates of deposit	4,363		—		—			4,363
	$	55,988	$	13	$	(11	)	$	55,990

Investments are exposed to various risks, including interest rate, market and credit risk and as a result, it is possible that changes in the values of these investments may occur and that such changes could affect the amounts reported in the condensed consolidated balance sheets and condensed consolidated statements of income.