Cash and Investments in Marketable Securities (Tables)

12 Months Ended

Dec. 31, 2015

Fair Value Disclosures [Abstract]

Cash and Investments in Marketable Securities, Including Cash Equivalents and Restricted Cash

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

	Estimated Fair Value at
	December 31, 2015		December 31, 2014
Cash and cash equivalents	$	55,570	$	12,365
Short-term investments		253,374		225,459
Restricted cash		—		25,000
Total cash and investments in marketable securities	$	308,944	$	262,824

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		December 31, 2015		December 31, 2014
Corporate notes and bonds		2	$	181,969	$	182,544
Corporate commercial paper		2		61,150		42,915
Obligations of U.S. government agencies		2		7,325		—
Available-for-sale investments				250,444		225,459
Money market funds		1		53,728		11,229
Certificate of deposit	N/A			2,930		—
Cash, including restricted cash	N/A			1,842		26,136
Total cash and investments in marketable securities			$	308,944	$	262,824