Marketable Securities

12 Months Ended

Dec. 31, 2011

Marketable Securities [Abstract]

Marketable Securities

Marketable Securities

The carrying amounts of marketable securities were as follows (in thousands):

December 31, 2011	Held-to-Maturity		Trading		Total
U.S. Government and agency obligations	$	40,240	$	—	$	40,240
Commercial paper	24,980		—		24,980
Municipal bonds	2,057		—		2,057
Corporate bonds	3,131		—		3,131
Total short-term marketable securities	70,408		—		70,408
U.S. Government and agency obligations	65,109		—		65,109
Municipal bonds	8,909		—		8,909
Corporate bonds	5,232		—		5,232
Total long-term marketable securities	79,250		—		79,250
Total marketable securities	$	149,658	$	—	$	149,658

December 31, 2010
U.S. Government and agency obligations	$	40,047	$	—	$	40,047
Commercial paper	33,971		—		33,971
Municipal bonds	10,896		—		10,896
Corporate bonds	10,122		—		10,122
Equity securities - mutual funds	—		14,411		14,411
Total short-term marketable securities	95,036		14,411		109,447
U.S. Government and agency obligations	30,618		—		30,618
Municipal bonds	3,641		—		3,641
Total long-term marketable securities	34,259		—		34,259
Total marketable securities	$	129,295	$	14,411	$	143,706

Scheduled maturities of held-to-maturity investments were as follows (in thousands):

December 31, 2011
Due within one year	$	70,408
Due in one to five years	79,250
Total	$	149,658