Investments (Tables)

3 Months Ended

Mar. 31, 2016

Investments, Debt and Equity Securities [Abstract]

Schedule of Available-for-sale Securities Reconciliation

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