Cash and Investments in Marketable Securities (Tables)

9 Months Ended

Sep. 30, 2017

Fair Value Disclosures [Abstract]

Cash and Investments in Marketable Securities, Including Cash Equivalents

Cash and investments in marketable securities, including cash equivalents, are as follows (in thousands):

	Estimated Fair Value at
	September 30, 2017		December 31, 2016
Cash and cash equivalents	$	37,967	$	59,640
Short-term investments		314,600		329,462
Long-term investments		59,596		—
Total cash and investments in marketable securities	$	412,163	$	389,102

Portfolio of Cash and Investments in Marketable Securities

Our portfolio of cash and investments in marketable securities includes (in thousands):

			Estimated Fair Value at
	Fair Value Hierarchy Level		September 30, 2017		December 31, 2016
Corporate notes and bonds		2	$	213,978	$	156,044
Corporate commercial paper		2		160,786		160,920
Obligations of U.S. government agencies		2		7,249		13,749
Available-for-sale investments				382,013		330,713
Money market funds		1		27,058		51,104
Certificate of deposit	N/A			2,930		2,930
Cash	N/A			162		4,355
Total cash and investments in marketable securities			$	412,163	$	389,102