Note 3. Investments

Available-for-sale investments consist of fixed-income securities that are accounted for at fair value. Premiums and discounts paid on securities at the time of purchase are recorded as accrued interest and amortized over the period of maturity. The amortized cost and fair value on the available-for-sale investments and unrealized gains and losses as of December 31, 2016 and 2015 were as follows (in thousands):

	December 31, 2016
	Amortized		Gross Unrealized		Gross Unrealized			Fair
	Cost		Gains		Losses			Value
Amounts maturing in one year or less
Corporate notes and obligations	$	29,866	$	—	$	(25	)	$	29,841
U.S. government treasury securities		6,900		—		—			6,900
Total short-term available-for-sale debt securities	$	36,766	$	—	$	(25	)	$	36,741

Amounts maturing in greater than one year
Corporate notes and obligations	$	4,010	$	—	$	(11	)	$	3,999
U.S. government treasury securities		34,505		—		(58	)		34,447
Total long-term available-for-sale debt securities	$	38,515	$	—	$	(69	)	$	38,446

	December 31, 2015
	Amortized		Gross Unrealized		Gross Unrealized			Fair
	Cost		Gains		Losses			Value
Amounts maturing in one year or less
Corporate notes and obligations	$	2,245	$	—	$	—		$	2,245
U.S. agency securities		3,016		—		(1	)		3,015
U.S. government treasury securities		999		1		—			1,000
Total available-for-sale debt securities	$	6,260	$	1	$	(1	)	$	6,260

As of December 31, 2016 and 2015, the Company did not consider any of the unrealized losses on its investments to be other-than-temporarily impaired based on its evaluation of available evidence. None of the investments held as of December 31, 2016 and 2015 have been in a continuous unrealized loss position for more than 12 months. Realized gains and losses on sales of available-for-sale securities were immaterial for all periods presented.