Available-for-Sale Securities

3 Months Ended

Mar. 31, 2015

Available-for-Sale Securities

Available-for-Sale Securities

5.  Available-for-Sale Securities

The following tables summarize the available-for-sale securities held at March 31, 2015 and December 31, 2014 (in thousands):

	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses			Fair Value
March 31, 2015
U.S. Treasury securities	$	145,668	$	8	$	(6	)	$	145,670
U.S. government-sponsored securities	6,502		1		—			6,503
Total	$	152,170	$	9	$	(6	)	$	152,173

	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses			Fair Value
December 31, 2014
U.S. Treasury securities	$	150,055	$	2	$	(25	)	$	150,032
U.S. government-sponsored securities	24,001		4		—			24,005
Total	$	174,056	$	6	$	(25	)	$	174,037

The contractual maturities of all securities held at March 31, 2015 are one year or less. There were 15 and 27 available-for-sale securities in an unrealized loss position at March 31, 2015 and December 31, 2014, respectively, none of which had been in an unrealized loss position for more than twelve months. The aggregate fair value of these securities at March 31, 2015 and December 31, 2014 was approximately $56.8 million and approximately $101.9 million, respectively. The Company reviews its investments for other-than-temporary impairment whenever the fair value of an investment is less than amortized cost and evidence indicates that an investment’s carrying amount is not recoverable within a reasonable period of time. To determine whether an impairment is other-than-temporary, the Company considers whether it has the ability and intent to hold the investment until a market price recovery and considers whether evidence indicating the cost of the investment is recoverable outweighs evidence to the contrary. The Company does not intend to sell the investments and it is not more likely than not that the Company will be required to sell the investments before recovery of their amortized cost bases, which may be maturity. The Company did not hold any securities with other-than-temporary impairment at March 31, 2015.

There were no sales of available-for-sale securities during the three months ended March 31, 2015 or 2014. Gross realized gains and losses on the sales of available-for-sale securities that have been included in other (expense) income, net unrealized holding gains or losses for the period that have been included in accumulated other comprehensive income as well as gains and losses reclassified out of accumulated other comprehensive income into other (expense) income were not material to the Company’s consolidated results of operations. The cost of securities sold or the amount reclassified out of the accumulated other comprehensive income into other (expense) income is based on the specific identification method for purposes of recording realized gains and losses.