Note 3. Available-for-sale Securities

The following is a summary of available-for-sale securities at March 31, 2016 (in thousands):


	March 31, 2016
	Amortized Cost		Gross Unrealized Gain		Gross Unrealized Loss			Fair Value
Money market funds	$	6,648	$	—	$	—		$	6,648
United States government agency securities		9,996		1		—			9,997
Corporate debt securities		60,465		72		(21	)		60,516
Marketable equity securities		—		5,082		—			5,082

Total available-for-sale securities	$	77,109	$	5,155	$	(21	)	$	82,243

The following is a summary of available-for-sale securities at December 31, 2015 (in thousands):


	December 31, 2015
	Amortized Cost		Gross Unrealized Gain		Gross Unrealized Loss			Fair Value
Money market funds	$	59,302	$	—	$	—		$	59,302
Corporate debt securities		25,747		—		(49	)		25,698
Marketable equity securities		—		11,163		—			11,163

Total available-for-sale securities	$	85,049	$	11,163	$	(49	)	$	96,163

Available-for-sale securities at March 31, 2016 and December 31, 2015, consisted of the following by contractual maturity (in thousands):


	March 31, 2016				December 31, 2015
	Amortized Cost		Fair Value		Amortized Cost		Fair Value
One year or less	$	56,934	$	56,934	$	85,049	$	85,000
Marketable equity securities		—		5,082		—		11,163
Greater than one year and less than five years		20,175		20,227		—		—

Total available-for-sale securities	$	77,109	$	82,243	$	85,049	$	96,163

The following tables show all available-for-sale marketable securities in an unrealized loss position for which an other-than-temporary impairment has not been recognized and the related gross unrealized losses and fair value, aggregated by investment category and length of time that individual securities have been in a continuous unrealized loss position (in thousands):


	March 31, 2016
	Less than 12 Months					12 Months or Greater					Total
	Fair Value		Unrealized Loss			Fair Value		Unrealized Loss			Fair Value		Unrealized Loss
Corporate debt securities	$	18,137	$	(21	)	$	—	$	—		$	18,137	$	(21	)

Total available-for-sale securities	$	18,137	$	(21	)	$	—	$	—		$	18,137	$	(21	)


	December 31, 2015
	Less than 12 Months					12 Months or Greater					Total
	Fair Value		Unrealized Loss			Fair Value		Unrealized Loss			Fair Value		Unrealized Loss
Corporate debt securities	$	20,170	$	(46	)	$	5,528	$	(3	)	$	25,698	$	(49	)

Total available-for-sale securities	$	20,170	$	(46	)	$	5,528	$	(3	)	$	25,698	$	(49	)

As of March 31, 2016, the Company considered the declines in market value of its marketable securities investment portfolio to be temporary in nature and did not consider any of its investments other-than-temporarily impaired. The Company typically invests in highly-rated securities, and its investment policy limits the amount of credit exposure to any one issuer. The policy generally requires investments to be investment grade, with the primary objective of minimizing the potential risk of principal loss. Fair values were determined for each individual security in the investment portfolio. When evaluating an investment for other-than-temporary impairment, the Company reviews factors such as the length of time and extent to which fair value has been below its cost basis, the financial condition of the issuer and any changes thereto, changes in market interest rates, and the Company’s intent to sell, or whether it is more likely than not it will be required to sell, the investment before recovery of the investment’s cost basis. During the three months ended March 31, 2016 and 2015, the Company did not recognize any other-than-temporary impairment loss. The Company has no current requirement or intent to sell the securities in an unrealized loss position. The Company expects to recover up to (or beyond) the initial cost of investment for securities held.

The Company did not record any gross realized gains from the sale or maturity of available-for-sale investments during the three months ended March 31, 2016 and 2015. The Company did not record any gross realized losses from the sale or maturity of available-for-sale investments during the three months ended March 31, 2016 and 2015.