Investments and Fair Value Measurements

6 Months Ended

Jun. 30, 2019

Investments And Fair Value Measurements [Abstract]

3.	Investments and Fair Value Measurements

Investments

As of June 30, 2019 and December 31, 2018, we primarily invested our excess cash in money market funds and debt instruments of the U.S. Treasury, financial institutions, corporations and U.S. government agencies with strong credit ratings and an investment grade rating at or above A-1, P-1 or F-1 by Moody’s, S&P or Fitch, respectively. We have established guidelines relative to diversification and maturities that maintain safety and liquidity. We periodically review and modify these guidelines to maximize trends in yields and interest rates without compromising safety and liquidity.

The following is a summary of our investments at June 30, 2019 and December 31, 2018 (in thousands):

			Gross Unrealized					Estimated
June 30, 2019	Cost		Gains		Losses			Fair Value
Available-for-sale securities:
Corporate debt securities	$	62,426	$	25	$	(49	)	$	62,402
Debt securities issued by U.S. government agencies		60,476		88		—			60,564
Total securities with a maturity of one year or less	$	122,902	$	113	$	(49	)	$	122,966

Corporate debt securities		22,443		—		(35	)		22,408
Total securities with a maturity of one to two years		22,443		—		(35	)		22,408
Total available-for-sale securities	$	145,345	$	113	$	(84	)	$	145,374

			Gross Unrealized					Estimated
December 31, 2018	Cost		Gains		Losses			Fair Value
Available-for-sale securities:
Corporate debt securities	$	81,770	$	—	$	(151	)	$	81,619
Debt securities issued by U.S. government agencies		85,578		—		(42	)		85,536
Total securities with a maturity of one year or less	$	167,348	$	—	$	(193	)	$	167,155

We recorded unrealized gains (losses) related to the securities listed above as of June 30, 2019 and December 31, 2018. We believe that the decline in value of some of our securities is temporary and primarily related to the change in market interest rates since purchase. We believe it is more likely than not that we will be able to hold our debt securities to maturity. Therefore, we anticipate a full recovery of the amortized cost basis of our debt securities at maturity.

All of our available-for-sale securities are available to us for use in our current operations. As a result, we categorized all of these securities as current assets even though the stated maturity of some individual securities may be one year or more beyond the balance sheet date.

Fair Value Measurements

The following tables present the investments we held at June 30, 2019 and December 31, 2018 that are regularly measured and carried at fair value. The table segregates each security by the level within the fair value hierarchy of valuation techniques we utilized to determine the respective security’s fair value (in thousands):

	At June 30, 2019		Quoted Prices in Active Markets (Level 1)		Significant Other Observable Inputs (Level 2)
Money market funds (1)	$	131,241	$	131,241	$	—
Corporate debt securities (3)		84,811		—		84,811
Debt securities issued by U.S. government agencies (3)		60,563		—		60,563
Total	$	276,615	$	131,241	$	145,374

	At December 31, 2018		Quoted Prices in Active Markets (Level 1)		Significant Other Observable Inputs (Level 2)
Money market funds (1)	$	82,343	$	82,343	$	—
Corporate debt securities (2)		81,619		—		81,619
Debt securities issued by U.S. government agencies (3)		85,536		—		85,536
Total	$	249,498	$	82,343	$	167,155

(1)

Included in cash and cash equivalents on our condensed consolidated balance sheets.

(2)

At December 31, 2018, $1.0 million was included in cash and cash equivalents on our condensed consolidated balance sheet, with the difference included in short-term investments on our condensed consolidated balance sheet.

(3)

Included in short-term investments on our condensed consolidated balance sheets.