Investments

The following tables summarize our short-term investments (dollars in thousands):



		As of March 31, 2016
	Maturity	Amortized cost		Gross unrealized gains		Gross unrealized losses		Estimated fair value
Corporate debt securities	1 year or less	$	26,018	$	6	$	—	$	26,024
Commercial paper	1 year or less	47,037		53		—		47,090
		$	73,055	$	59	$	—	$	73,114



		As of December 31, 2015
	Maturity	Amortized cost		Gross unrealized gains		Gross unrealized losses			Estimated fair value
Corporate debt securities	1 year or less	$	27,644	$	—	$	(22	)	$	27,622
Commercial paper	1 year or less	45,158		54		—			45,212
		$	72,802	$	54	$	(22	)	$	72,834

Unrealized gains and losses on available-for-sale securities are included as a component of comprehensive loss. At March 31, 2016, the Company did not have any securities in material unrealized loss positions. The Company reviews its investments to identify and evaluate investments that have an indication of possible other-than-temporary impairment. Factors considered in determining whether a loss is other-than-temporary include the length of time and extent to which fair value has been less than the cost basis, the financial condition and near-term prospects of the investee, and the Company’s intent and ability to hold the investment for a period of time sufficient to allow for any anticipated recovery in market value. The Company does not intend to sell any investments prior to recovery of their amortized cost basis for any investments in an unrealized loss position.