Investments

Our investments are classified as held-to-maturity as we have both the intent and ability to hold the investments until their individual maturities. The amortized cost, gross unrealized gains and losses, and fair value of our investments as measured using Level 2 inputs (in thousands) were as follows:



	As of March 31, 2017
			Gross		Gross
	Amortized		Unrealized		Unrealized		Fair
	Costs		Gains		Losses		Value
U.S. Treasury bills	$	28,073	$	40	$	29	$	28,084
Corporate bonds	5,611		24		1		5,634
Total investments	$	33,684	$	64	$	30	$	33,718


	As of December 31, 2016
			Gross		Gross
	Amortized		Unrealized		Unrealized		Fair
	Costs		Gains		Losses		Value
U.S. Treasury bills	$	28,119	$	116	$	27	$	28,208
Corporate bonds	16,222		81		8		16,295
Total investments	$	44,341	$	197	$	35	$	44,503

The amortized cost and fair value of our investments by contractual maturities (in thousands) were as follows:



	As of March 31, 2017				As of December 31, 2016
	Amortized		Fair			Amortized		Fair
	Costs		Value			Costs		Value
Due in one year or less	$	33,684	$	33,718		$	44,341	$	44,503
Due after one year through five years	—		—			—		—
Total	$	33,684	$	33,718		$	44,341	$	44,503

The following table summarizes our held-to-maturity securities in an unrealized loss position as of the periods noted below. These securities are aggregated by major security type and length of time that the individual securities have been in a continuous unrealized loss position (in thousands, except number of securities):

As of March 31, 2017

As of December 31, 2016

Number of

Fair

Unrealized

Number of

Fair

Unrealized

Securities

Value

Losses

Securities

Value

Losses

Unrealized loss for less than twelve months

U.S. Treasury bills

12,011

4,002

We did not hold any securities in a continuous unrealized loss position for twelve months or longer as of March 31, 2017, or December 31, 2016.

When a held-to-maturity investment is in an unrealized loss position, we assess whether or not we expect to recover the entire cost basis of security, based on our best estimate of the present value of cash flows expected to be collected from the debt security. Factors considered in our analysis include the reasons for the unrealized loss position, the severity and duration of the unrealized loss position, credit worthiness and forecasted performance of the investee. In cases where the estimated present value of future cash flows is less than our cost basis, we recognize an other than temporary impairment and write the investment down to its fair value. The new cost basis would not be changed for subsequent recoveries in fair value. While some of the securities held in the investment portfolio have decreased in value since the date of acquisition, the severity of loss and the duration of the loss position are not significant for the three months ended March 31, 2017 and 2016, respectively. The Company does not intend, nor does the Company believe that it is likely, that the Company will be required to sell these securities before the recovery of the cost basis.