Cash and Cash Equivalents and Investments in Marketable Securities

Our investment portfolio at June 30, 2016 consisted of cash, cash equivalents and investments in marketable securities.

We currently invest in marketable debt securities with the maximum maturity or put date of any individual issue generally not greater than one year from the date of purchase, which are usually held until maturity. All of these instruments are classified as available-for-sale and are reported at fair value. Interest income is recorded as earned. Unrealized gains and losses, net of related income taxes, are reported as a component of accumulated other comprehensive income. Upon sale or maturity, realized gains on our marketable debt securities are recognized as interest income. These gains are computed based on the specific identification of the underlying cost of the securities, net of unrealized gains and losses previously reported in other comprehensive income. Unrealized gains and losses on our available-for-sale securities are due to changes in market prices and are considered temporary.

The following is a summary of our marketable securities as of June 30, 2016 and December 31, 2015:



	Amortized Cost		Gross Unrealized Gain		Gross Unrealized Loss			Fair Value (Net Carrying Amount)
	(In thousands)
June 30, 2016
Certificates of deposit	$	1,700	$	—	$	—		$	1,700
Commercial paper	17,424		6		—			17,430
Corporate debt securities	16,038		—		(5		)	16,033
State and political subdivisions debt securities	46,158		9		(2		)	46,165
Total marketable securities	$	81,320	$	15	$	(7	)	$	81,328

December 31, 2015
Commercial paper	$	22,876	$	1	$	(2	)	$	22,875
Corporate debt securities	32,311		—		(41		)	32,270
State and political subdivisions debt securities	88,935		6		(67		)	88,874
Total marketable securities	$	144,122	$	7	$	(110	)	$	144,019

Interest income recognized on our marketable securities was $0.1 million and $0.5 million for the three months ended June 30, 2016 and 2015, respectively, and $0.1 million and $0.9 million for the six months ended June 30, 2016 and 2015, respectively.