NOTE B – Financial Instruments

We invest primarily in money market funds, highly liquid debt instruments of the U.S. government, and U.S. corporate debt securities. All highly liquid investments with original maturities of 90 days or less are classified as cash equivalents. All investments with original maturities greater than 90 days and remaining maturities less than one year from the balance sheet date are classified as short-term marketable securities. Investments with remaining maturities of more than one year from the balance sheet date are classified as marketable securities, non-current. Short-term marketable securities and marketable securities, non-current, are also classified as available-for-sale. We intend to hold marketable securities until maturity; however, we may sell these securities at any time for use in current operations or for other purposes. Consequently, we may or may not keep securities with stated holding periods to maturity.

Our fixed income investments are carried at fair value and unrealized gains and losses on these investments are included in other comprehensive income (loss) in the condensed consolidated statements of comprehensive income (loss). Realized gains or losses are included in other income (expense) in the condensed consolidated statements of comprehensive income (loss). When a determination has been made that an other-than-temporary decline in fair value has occurred, the amount of the decline that is related to a credit loss is realized and is included in other income (expense), net in the condensed consolidated statements of comprehensive income (loss).

Cash equivalents and marketable securities, consisted of the following:


	March 31, 2017
	Amortized Cost		Unrealized Gains (Losses)			Fair Value
	(Dollars in thousands)
Cash equivalents:
Money market funds	$	80,310	$	—		$	80,310
Marketable securities:
Corporate bonds		15,681		(120	)		15,561
Commercial paper		4,995		—			4,995
U.S. treasury securities		7,489		8			7,497

	$	108,475	$	(112	)	$	108,363


Due within one year						$	105,860
Due within two years							2,503

Total						$	108,363


	December 31, 2016
	Amortized Cost		Unrealized Gains (Losses)			Fair Value
	(Dollars in thousands)
Cash equivalents:
Money market funds	$	75,375	$	—		$	75,375
Marketable securities:
Corporate bonds		15,681		(96	)		15,585
Commercial paper		4,977		10			4,987
U.S. treasury securities		7,489		10			7,499
U.S. agency obligations		2,497		3			2,500

	$	106,019	$	(73	)	$	105,946


Due within one year						$	98,452
Due within two years							7,494

Total						$	105,946

We do not believe any of the unrealized losses represent an other-than-temporary impairment based on our valuation of available evidence as of March 31, 2017. We expect to receive the full principal and interest on all of these cash equivalents and marketable securities.

Fair Value Measurements

We measure certain financial assets at fair value on a recurring basis based on a fair value hierarchy that requires us to maximize the use of observable inputs and minimize the use of unobservable inputs when measuring fair value. A financial instrument’s categorization within the fair value hierarchy is based upon the lowest level of input that is significant to the fair value measurement. The three levels of inputs that may be used to measure fair value are:

•

Level 1 – quoted prices in active markets for identical assets or liabilities

•

Level 2 – observable inputs other than Level 1 prices, such as (a) quoted prices for similar assets or liabilities, (b) quoted prices in markets with insufficient volume or infrequent transactions (less active markets), or (c) model-derived valuations in which all significant inputs are observable or can be derived principally from or corroborated by observable market data for substantially the full term of the assets or liabilities.

•

Level 3 – unobservable inputs to the valuation methodology that are significant to the measurement of fair value of assets or liabilities.

Level 1 Measurements

Our cash equivalents held in money market funds are measured at fair value using level 1 inputs.

Level 2 Measurements

Our available-for-sale U.S. treasury securities, U.S. agency obligations, commercial paper and corporate debt securities are measured at fair value using level 2 inputs. We obtain the fair values of our level 2 available-for-sale securities from a professional pricing service.

The following tables present information about our financial assets that are measured at fair value on a recurring basis and indicates the fair value hierarchy of the valuation techniques utilized to determine such fair value:


	March 31, 2017
	Level 1		Level 2		Level 3		Total
	(Dollars in thousands)
Assets:
Cash and cash equivalents:
Money market funds	$	80,310	$	—	$	—	$	80,310
Marketable securities:
Corporate bonds		—		15,561		—		15,561
Commerical paper		—		4,995		—		4,995
U.S. treasury securities		—		7,497		—		7,497

Total	$	80,310	$	28,053	$	—	$	108,363


	December 31, 2016
	Level 1		Level 2		Level 3		Total
	(Dollars in thousands)
Assets:
Cash and cash equivalents:
Money market funds	$	75,375	$	—	$	—	$	75,375
Marketable securities:
Corporate bonds		—		15,585		—		15,585
Commerical paper		—		4,987		—		4,987
U.S. treasury securities		—		7,499		—		7,499
U.S. agency obligations		—		2,500		—		2,500

Total	$	75,375	$	30,571	$	—	$	105,946

We classify our cash and cash equivalents and marketable securities within Level 1 or Level 2 because we use quoted market prices or alternative pricing sources and models utilizing market observable inputs to determine their fair value.