Marketable Investments (Tables)

12 Months Ended

Dec. 31, 2012

Marketable Investments

Schedule of marketable investments classified as held-to-maturity

Marketable investments classified as held-to-maturity consist of the following (in thousands):

	December 31, 2012
	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses			Fair Value
Government-sponsored enterprises	$	350,043	$	261	$	(35	)	$	350,269
Corporate notes and bonds		280,385		184		(140	)		280,429
Total	$	630,428	$	445	$	(175	)	$	630,698
Reported under the following captions on the consolidated balance sheet:
Current marketable investments	$	325,175
Noncurrent marketable investments		305,253
	$	630,428

	December 31, 2011
	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses			Fair Value
Government-sponsored enterprises	$	308,202	$	155	$	(170	)	$	308,187
Corporate notes and bonds		276,118		113		(442	)		275,789
Total	$	584,320	$	268	$	(612	)	$	583,976
Reported under the following captions on the consolidated balance sheet:
Current marketable investments	$	240,803
Noncurrent marketable investments		343,517
	$	584,320

Summary of gross unrealized losses and the length of time marketable investments have been in a continuous unrealized loss position

The following table summarizes gross unrealized losses and the length of time marketable investments have been in a continuous unrealized loss position (in thousands):

	December 31,
	2012					2011
	Fair Value		Gross Unrealized Loss			Fair Value		Gross Unrealized Loss
Government-sponsored enterprises:
Less than one year	$	72,727	$	(35	)	$	170,018	$	(170	)
Greater than one year		—		—			—		—
		72,727		(35	)		170,018		(170	)
Corporate notes and bonds:
Less than one year		90,960		(140	)		149,383		(442	)
Greater than one year		—		—			—		—
		90,960		(140	)		149,383		(442	)
Total	$	163,687	$	(175	)	$	319,401	$	(612	)

Summary of the contractual maturities of held-to-maturity marketable investments

The following table summarizes the contractual maturities of held-to-maturity marketable investments at December 31, 2012 (in thousands):

	December 31, 2012
	Amortized Cost		Fair Value
Due in less than one year	$	325,175	$	325,392
Due in one to two years		305,253		305,306
Due in three to five years		—		—
Due after five years		—		—
Total	$	630,428	$	630,698