Marketable Securities, Available-for-sale (Tables)

12 Months Ended

Dec. 31, 2012

Marketable Securities, Available-for-sale

Fair value of the available-for-sale marketable securities, by type of security

	DECEMBER 31, 2012
(in thousands)		AMORTIZED COST		GROSS UNREALIZED GAINS		GROSS UNREALIZED LOSSES			ESTIMATED FAIR VALUE
Type of security:
U.S. Treasury securities	$	3,098	$	1	$	–		$	3,099
Obligations of U.S. and local government agencies		154,774		1,008		(489	)		155,293
Corporate debt securities		165,153		116		(75	)		165,194
Asset-backed securities		27,325		153		(164	)		27,314
Total debt securities		350,350		1,278		(728	)		350,900
Short-term pooled investments		37,127		–		(7	)		37,120
Total marketable securities, available-for-sale	$	387,477	$	1,278	$	(735	)	$	388,020

	DECEMBER 31, 2011
Type of security:
U.S. Treasury securities	$	1,557	$	–	$	(2	)	$	1,555
Obligations of U.S. and local government agencies		147,557		123		(860	)		146,820
Corporate debt securities issued under U.S. government/agency-backed programs		1,453		3		–			1,456
Corporate debt securities		126,088		101		(523	)		125,666
Asset-backed securities		46,198		42		(496	)		45,744
Total debt securities		322,853		269		(1,881	)		321,241
Time deposits		25,500		–		–			25,500
Short-term pooled investments		275		–		–			275
Total marketable securities, available-for-sale	$	348,628	$	269	$	(1,881	)	$	347,016

Fair value of the available-for-sale marketable securities, by contractual maturity

	DECEMBER 31,
(in thousands)		2012		2011
Contractual maturity:
Maturing in one year or less	$	68,347	$	167,413
Maturing after one year through three years		257,595		120,952
Maturing after three years		24,958		32,876
Total debt securities		350,900		321,241
Time deposits and short-term pooled investments		37,120		25,775
Total marketable securities, available-for-sale	$	388,020	$	347,016