3.INVESTMENTS

The following table summarizes the Company’s investments at:

June 30, 2017	Amortized Cost		Gross Unrealized Holding Gains		Gross Unrealized Holding Losses		Fair Value		Continuous Unrealized Loss Position less than 12 Months		Continuous Unrealized Loss Position greater than 12 Months
Available-for-sale
Short-term:
Commercial paper	$	73,037	$	3	$	-	$	73,040	$	-	$	-
Certificates of deposit	37,210		-		-		37,210		-		-
Municipal securities	152,287		8		42		152,253		42		-
U.S. government agency securities	28,465		-		22		28,443		22		-
Variable rate demand notes	32,905		-		-		32,905		-		-
Long-term:
Municipal securities	32,704		-		17		32,687		17		-
U.S. government agency securities	15,974		-		22		15,952		22		-

Total	$	372,582	$	11	$	103	$	372,490	$	103	$	-


December 31, 2016	Amortized Cost		Gross Unrealized Holding Gains		Gross Unrealized Holding Losses		Fair Value		Continuous Unrealized Loss Position less than 12 Months		Continuous Unrealized Loss Position greater than 12 Months

Available-for-sale
Short-term:
Commercial paper	$	40,382	$	-	$	-	$	40,382	$	-	$	-
Municipal securities	140,379		-		181		140,198		181		-
U.S. government agency securities	26,057		-		6		26,051		6		-
Variable rate demand notes	13,923		-		-		13,923		-		-
Long-term:
Municipal securities	2,403		-		9		2,394		9		-

Total	$	223,144	$	-	$	196	$	222,948	$	196	$	-

During the three- and six-months ended June 30, 2017 and 2016, realized gains or losses recognized on the sale of investments were not significant.

The Company’s investments at June 30, 2017 and December 31, 2016 in commercial paper, certificates of deposit, municipal securities, U.S. government agency securities and/or variable rate demand notes (“VRDNs”) carried investment grade credit ratings. VRDNs are floating rate municipal bonds with embedded put options that allow the bondholder to sell the security at par plus accrued interest. All of the put options are secured by a pledged liquidity source. While they are classified as marketable investment securities, the put option allows the VRDNs to be liquidated at par on a same day, or more generally, on a seven day settlement basis.

The following table summarizes the underlying contractual maturities of the Company’s investments at:

	June 30, 2017				December 31, 2016

	Amortized Cost		Fair Value		Amortized Cost		Fair Value
Less than 1 year:
Commercial paper	$	73,037	$	73,040	$	40,382	$	40,382
Certificates of deposit	37,210		37,210		-		-
Municipal securities	152,287		152,253		140,379		140,198
U.S. government agency securities	28,465		28,443		26,057		26,051
Due 1 -10 years:
Municipal securities	32,704		32,687		2,403		2,394
U.S. government agency securities	15,974		15,952		-		-
Variable rate demand notes	3,918		3,918		3,917		3,917
Due 11 - 20 years:
Variable rate demand notes	10,006		10,006		6,003		6,003
Due 21 - 30 years:
Variable rate demand notes	14,979		14,979		4,003		4,003
Due 31 - 40 years:
Variable rate demand notes	4,002		4,002		-		-

Total	$	372,582	$	372,490	$	223,144	$	222,948