5.Cash, Cash Equivalents and Available for Sale Securities

The Company considers all highly liquid investments purchased with original maturities of 90 days or less at the date of purchase to be cash equivalents. Cash and cash equivalents included cash of $5.3 million and $4.7 million at March 31, 2015 and December 31, 2014, respectively. Cash and cash equivalents at March 31, 2015 and December 31, 2014 also included investments of $34.3 million and $35.1 million, respectively, in U.S. Treasury securities with original maturities of 90 days or less and investments in money market funds that invest in U.S. Treasury Securities.

The Company held available for sale securities with a fair value totaling $393.7 million and $423.7 million at March 31, 2015 and December 31, 2014, respectively. These available for sale securities consisted of U.S. Treasury securities and had maturities of greater than 90 days and less than one year. The Company evaluates securities with unrealized losses, if any, to determine whether such losses are other than temporary. The Company has determined that there were no other than temporary declines in fair values of its investments as of March 31, 2015. The Company classifies these securities as available for sale, however, the Company does not currently intend to sell its investments and the Company believes it is more likely than not that the Company will recover the carrying value of these investments.

Available for sale securities, including carrying value and estimated fair values, are summarized as follows:

	As of March 31, 2015
	Cost		Fair Value		Carrying Value		Unrealized Loss

U.S. Treasury securities - maturities < 1 year	$	393,747	$	393,718	$	393,718	$	(29	)
U.S. Treasury securities - maturities > 1 year	—		—		—		—
Total	$	393,747	$	393,718	$	393,718	$	(29	)

	As of December 31, 2014
	Cost		Fair Value		Carrying Value		Unrealized Loss

U.S. Treasury securities - maturities < 1 year	$	423,859	$	423,746	$	423,746	$	(113	)
U.S. Treasury securities - maturities > 1 year	$	—	$	—	$	—	$	—
Total	$	423,859	$	423,746	$	423,746	$	(113	)

The Company’s available for sale securities are reported at fair value on the Company’s balance sheet. Unrealized gains and losses are reported within accumulated other comprehensive income (loss) in the statements of comprehensive income (loss). The changes in accumulated other comprehensive loss associated with the unrealized loss on available for sale securities during the three months ended March 31, 2015 and March 31,2014 were as follows:

	Three months ended March 31,
	2015			2014

Beginning balance	$	(65	)	$	—
Current period changes in fair value, net of tax	48			18
Ending balance	$	(17	)	$	18