Cash and Investments in Marketable Securities (Tables)

9 Months Ended

Sep. 30, 2016

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, 2016		December 31, 2015
Cash and cash equivalents	$	63,295	$	55,570
Short-term investments		190,216		253,374
Total cash and investments in marketable securities	$	253,511	$	308,944

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, 2016		December 31, 2015
Corporate notes and bonds		2	$	74,564	$	181,969
Corporate commercial paper		2		95,924		61,150
Obligations of U.S. government agencies		2		16,798		7,325
Available-for-sale investments				187,286		250,444
Money market funds		1		62,092		53,728
Certificate of deposit	N/A			2,930		2,930
Cash	N/A			1,203		1,842
Total cash and investments in marketable securities			$	253,511	$	308,944