Available-For-Sale Securities (Tables)

9 Months Ended

Sep. 30, 2011

Available-For-Sale Securities [Abstract]

Summary Of Available-For-Sale Debt And Equity Securities At Estimated Fair Value

	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses			Estimated Fair Value
September 30, 2011
Debt securities:
U.S. treasury securities	$	1,147,146	$	8,505	$	(322	)	$	1,155,329
Money market funds		372,260		—		—			372,260
U.S. government agencies and FDIC guaranteed securities		1,082,230		8,593		(236	)		1,090,587
Municipal debt securities		24,410		183		(2	)		24,591
Non-U.S. government securities		266,234		1,450		(30,606	)		237,078
Corporate debt securities		1,698,857		9,242		(4,231	)		1,703,868
Residential mortgage and asset-backed securities		317,371		1,063		(1,908	)		316,526
Student loan-backed securities		61,300		—		(4,793	)		56,507
Total debt securities		4,969,808		29,036		(42,098	)		4,956,746
Equity securities		1,451		3,816		—			5,267
Total	$	4,971,259	$	32,852	$	(42,098	)	$	4,962,013
December 31, 2010
Debt securities:
U.S. treasury securities	$	1,349,348	$	7,109	$	(1,020	)	$	1,355,437
Money market funds		520,063		—		—			520,063
U.S. government agencies and FDIC guaranteed securities		1,284,654		11,919		(463	)		1,296,110
Municipal debt securities		17,543		103		(21	)		17,625
Non-U.S. government securities		286,410		1,880		(86	)		288,204
Corporate debt securities		1,112,976		8,040		(1,762	)		1,119,254
Residential mortgage and asset-backed securities		277,359		923		(1,239	)		277,043
Student loan-backed securities		75,900		—		(5,129	)		70,771
Total debt securities		4,924,253		29,974		(9,720	)		4,944,507
Equity securities		1,451		3,180		—			4,631
Total	$	4,925,704	$	33,154	$	(9,720	)	$	4,949,138

Summary Of The Classification Of Available-For-Sale Debt And Equity Securities

	September 30, 2011		December 31, 2010
Cash and cash equivalents	$	389,256	$	538,946
Short-term marketable securities		1,347,776		1,190,789
Long-term marketable securities		3,224,981		3,219,403
Total	$	4,962,013	$	4,949,138

Summary Of Available-For-Sale Debt Securities By Contractual Maturity

	September 30, 2011				December 31, 2010
	Amortized Cost		Fair Value		Amortized Cost		Fair Value
Less than one year	$	1,732,877	$	1,737,032	$	1,726,095	$	1,729,735
Greater than one year but less than five years		3,103,055		3,090,532		3,022,744		3,044,114
Greater than five years but less than ten years		32,160		32,703		33,076		33,580
Greater than ten years		101,716		96,479		142,338		137,078
Total	$	4,969,808	$	4,956,746	$	4,924,253	$	4,944,507

Summary Of Gross Realized Gains And Losses Related To Sales Of Marketable Securities

	Three Months Ended September 30,						Nine Months Ended September 30,
	2011			2010			2011			2010
Gross realized gains on sales	$	4,830		$	1,290		$	13,784		$	10,588
Gross realized losses on sales	$	(644	)	$	(260	)	$	(2,421	)	$	(2,434	)

Summary Of Available-For-Sale Debt Securities In A Continuous Unrealized Loss Position Deemed Not To Be Other-Than-Temporarily Impaired

	Less Than 12 Months					12 Months or Greater					Total
	Gross Unrealized Losses			Estimated Fair Value		Gross Unrealized Losses			Estimated Fair Value		Gross Unrealized Losses			Estimated Fair Value
September 30, 2011
Debt securities:
U.S. treasury securities	$	(322	)	$	249,055	$	—		$	—	$	(322	)	$	249,055
U.S. government agencies and FDIC guaranteed securities		(236	)		179,879		—			—		(236	)		179,879
Municipal debt securities		(2	)		9,785		—			—		(2	)		9,785
Non-U.S. government securities		(30,604	)		25,314		(2	)		2,995		(30,606	)		28,309
Corporate debt securities		(4,182	)		548,008		(49	)		6,298		(4,231	)		554,306
Residential mortgage and asset-backed securities		(739	)		100,102		(1,169	)		60,755		(1,908	)		160,857
Student loan-backed securities		—			—		(4,793	)		56,507		(4,793	)		56,507
Total	$	(36,085	)	$	1,112,143	$	(6,013	)	$	126,555	$	(42,098	)	$	1,238,698
December 31, 2010
Debt securities:
U.S. treasury securities	$	(1,020	)	$	531,184	$	—		$	—	$	(1,020	)	$	531,184
U.S. government agencies and FDIC guaranteed securities		(463	)		226,176		—			—		(463	)		226,176
Municipal debt securities		(21	)		4,688		—			—		(21	)		4,688
Non-U.S. government securities		(86	)		44,317		—			—		(86	)		44,317
Corporate debt securities		(1,762	)		459,412		—			—		(1,762	)		459,412
Residential mortgage and asset-backed securities		(1,239	)		197,330		—			—		(1,239	)		197,330
Student loan-backed securities		—			—		(5,129	)		70,771		(5,129	)		70,771
Total	$	(4,591	)	$	1,463,107	$	(5,129	)	$	70,771	$	(9,720	)	$	1,533,878