Cash and Investments in Marketable Securities (Tables)

6 Months Ended

Jun. 30, 2013

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
	June 30, 2013		December 31, 2012
Cash and cash equivalents	$	41,432	$	25,437
Short-term investments		160,453		251,757
Restricted cash		25,000		25,000
Total cash and investments in marketable securities	$	226,885	$	302,194

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	June 30, 2013		December 31, 2012
Corporate notes and bonds	2	$	134,231	$	241,158
U.S. corporate commercial paper	2		36,725		3,990
Obligations of U.S. states and municipalities	2		1,500		1,504
Obligations of U.S. government agencies	2		—		6,108
Available-for-sale investments			172,456		252,760
Money market funds	1		26,934		22,487
Cash, including restricted cash	N/A		27,495		26,947
Total cash and investments in marketable securities		$	226,885	$	302,194