Short-term Investments (Tables)

9 Months Ended

Sep. 30, 2012

Investments, Debt and Equity Securities [Abstract]

Schedule of Available-for-sale Securities

Short-term investments, with an original maturity of over 90 days, consisted of the following (in thousands):

	As of September 30, 2012
	Amortized Cost		Unrealized Gain in Accumulated OCI		Unrealized Loss in Accumulated OCI			Aggregate Fair Value
Equity securities	$	7	$	—	$	(6	)	$	1
U.S. Treasury securities	499,731		142		—			499,873
Auction rate securities	1,210		6,859		—			8,069
Total short-term investments	$	500,948	$	7,001	$	(6	)	$	507,943

	As of December 31, 2011
	Amortized Cost		Unrealized Gain in Accumulated OCI		Unrealized Loss in Accumulated OCI			Aggregate Fair Value
Equity securities	$	7	$	—	$	(6	)	$	1
U.S. Treasury securities	299,939		32		—			299,971
Total short-term investments	$	299,946	$	32	$	(6	)	$	299,972