Marketable Securities (Tables)

9 Months Ended

Sep. 30, 2018

Investments, Debt and Equity Securities [Abstract]

Summary of Marketable Securities

Below is a summary of our marketable securities as of September 30, 2018 and December 31, 2017 (in thousands):

	September 30, 2018							December 31, 2017
	Amortized Cost		Unrealized Loss			Estimated Fair Value		Cost or Amortized Cost		Unrealized Gain, Net		Estimated Fair Value
Marketable securities	$	249,844	$	(1,006	)	$	248,838	$	276,567	$	361	$	276,928