Marketable Securities (Tables)

6 Months Ended

Jun. 30, 2011

Marketable Securities [Abstract]

Schedule of Marketable Securities

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

June 30, 2011	Held-to-Maturity		Trading		Total
U.S. Government and agency obligations	$	49,400	$	—	$	49,400
Commercial paper	19,986		—		19,986
Municipal bonds	5,685		—		5,685
Corporate bonds	3,184		—		3,184
Total short-term marketable securities	78,255		—		78,255
U.S. Government and agency obligations	40,144		—		40,144
Municipal bonds	4,091		—		4,091
Corporate bonds	5,345		—		5,345
Total long-term marketable securities	49,580		—		49,580
Total marketable securities	$	127,835	$	—	$	127,835

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

June 30, 2010
U.S. Government and agency obligations	$	30,388	$	—	$	30,388
Commercial paper	24,969		—		24,969
Municipal bonds	13,020		—		13,020
Equity securities - mutual funds	—		5,189		5,189
Total short-term marketable securities	68,377		5,189		73,566
U.S. Government and agency obligations	60,430		—		60,430
Municipal bonds	7,861		—		7,861
Total long-term marketable securities	68,291		—		68,291
Total marketable securities	$	136,668	$	5,189	$	141,857

Held-to-maturity Securities

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

June 30, 2011
Due within one year	$	78,255
Due in one to five years	49,580
Total	$	127,835