Marketable Securities (Tables)

6 Months Ended

Jun. 30, 2012

Investments, Debt and Equity Securities [Abstract]

Schedule of Contractual Maturities of Marketable Securities

The following table summarizes the contractual maturities of our marketable securities (at fair value and in thousands): 

	June 30, 2012		December 31, 2011
Short-term marketable securities:
Maturities of less than five years	$	52,012	$	68,711
Long-term marketable securities:
Maturities of more than ten years	4,661		6,946
Total marketable securities	$	56,673	$	75,657

Schedule of Composition of Marketable Securities

The following table summarizes the composition of our marketable securities (at fair value and in thousands):

	June 30, 2012		December 31, 2011
Short-term marketable securities:
Corporate and government bonds and notes and commercial paper	$	52,012	$	68,711
Long-term marketable securities:
Federally-insured or FFELP guaranteed student loans	4,661		6,946
Total marketable securities	$	56,673	$	75,657

Schedule of Composition of Auction Rate Securities

The following table summarizes the composition of our auction rate securities (in thousands):

	June 30, 2012					December 31, 2011
	Par Value		Fair Value		S&P  Credit  rating	Par Value		Fair Value		S&P  Credit  rating
Long-term marketable securities:
Federally-insured or FFELP guaranteed student loans	$	5,700	$	4,661	AA+	$	8,300	$	6,946	AAA
Total auction rate securities	$	5,700	$	4,661		$	8,300	$	6,946