Cash Equivalents and Investments (Tables)

12 Months Ended

Dec. 31, 2018

Cash and Cash Equivalents [Abstract]

Summary of cash and available-for-sale securities

The following tables summarize the Company’s cash and available-for-sale securities’ amortized cost, gross unrealized gains and fair value by significant investment category reported as cash and cash equivalents, or short-term investments as of December 31, 2018 and 2017:

							Reported as:
(in thousands)	Amortized Cost		Unrealized Gains		Estimated Fair Value		Cash and Cash Equivalents		Short-Term Investments
December 31, 2018
Cash	$	167,871	$	—	$	167,871	$	167,871	$	—
Money market funds	226,719		—		226,719		226,719		—
Total	$	394,590	$	—	$	394,590	$	394,590	$	—
December 31, 2017
Cash	$	109,703	$	—	$	109,703	$	109,703	$	—
Money market funds	417,563		—		417,563		417,563		—
Corporate securities	3,353		1,495		4,848		—		4,848
Total	$	530,619	$	1,495	$	532,114	$	527,266	$	4,848