Marketable Securities (Tables)

3 Months Ended

Mar. 31, 2012

Marketable Securities [Abstract]

Schedule of Marketable Securities

All marketable securities were classified as held-to-maturity for the dates presented and the carrying amounts of held-to-maturity securities were as follows:

(in thousands)	March 31, 2012		December 31, 2011		March 31, 2011
U.S. Government and agency obligations	$	35,123	$	40,240	$	48,240
Commercial paper	24,988		24,980		19,986
Municipal bonds	2,052		2,057		9,825
Corporate bonds	8,281		3,131		5,033
Total short-term marketable securities	70,444		70,408		83,084
U.S. Government and agency obligations	61,247		65,109		39,415
Municipal bonds	8,867		8,909		3,625
Corporate bonds	—		5,232		3,211
Total long-term marketable securities	70,114		79,250		46,251
Total marketable securities	$	140,558	$	149,658	$	129,335

Held-to-maturity Securities

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

March 31, 2012
Due within one year	$	70,444
Due in one to five years	70,114
Total	$	140,558