Investments (Tables)

9 Months Ended

Sep. 30, 2020

Investments, Debt and Equity Securities [Abstract]

Schedule of Short-Term Investments

The following tables summarize the Company's short-term investments (dollars in thousands):

		As of September 30, 2020
	Maturity	Amortized cost		Gross unrealized gains		Gross unrealized losses		Estimated fair value
Corporate debt securities	2 years or less	$	159,588	$	576	$	—	$	160,164
Commercial paper	1 year or less	154,795		296		—		155,091
U.S. Agency bonds	2 years or less	79,120		38		(3)		79,155
U.S. Treasury bills	1 year or less	53,176		30		—		53,206
		$	446,679	$	940	$	(3)	$	447,616

		As of December 31, 2019
	Maturity	Amortized cost		Gross unrealized gains		Gross unrealized losses		Estimated fair value
Corporate debt securities	2 years or less	$	160,065	$	233	$	(1)	$	160,297
Commercial paper	1 year or less	120,862		74		—		120,936
U.S. Agency bonds	2 years or less	50,745		41		(4)		50,782
U.S. Treasury bills	2 years or less	36,474		27		(1)		36,500
		$	368,146	$	375	$	(6)	$	368,515