Investments (Tables)

9 Months Ended

Sep. 30, 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 September 30, 2016
	Maturity	Amortized cost		Gross unrealized gains		Gross unrealized losses		Estimated fair value
Corporate debt securities	1 year or less	$	22,079	$	—	$	—	$	22,079
Commercial paper	1 year or less	31,037		64		—		31,101
		$	53,116	$	64	$	—	$	53,180

		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