Investments (Tables)

9 Months Ended

Sep. 30, 2011

Investments [Abstract]

Investments

	September 30, 2011		December 31, 2010
Available-for-sale securities:
U.S. Treasury and agency debt securities	$	461,949	$	340,384
Corporate and other debt securities		199,014		122,909
Asset-backed securities		97,661		33,154
Municipal debt securities		44,579		41,655
Foreign government debt securities		12,589		7,926
Total available-for-sale securities		815,792		546,028
Time deposits		294,265		139,391
Total investments	$	1,110,057	$	685,419

Amortized Cost, Gross Unrealized Gains And Losses And Fair Value Of Investment Securities Available-For-Sale

The amortized cost, unrealized gains and losses and fair value of available-for-sale investment securities at September 30, 2011 were as follows:

	Amortized Cost		Unrealized Gains		Unrealized Losses			Fair Value
U.S. Treasury and agency debt securities	$	460,087	$	2,192	$	(330	)	$	461,949
Corporate and other debt securities		198,644		955		(585	)		199,014
Asset-backed securities		97,612		200		(151	)		97,661
Municipal debt securities		44,616		84		(121	)		44,579
Foreign government debt securities		12,422		169		(2	)		12,589
Total available-for-sale investment securities	$	813,381	$	3,600	$	(1,189	)	$	815,792

The amortized cost, unrealized gains and losses and fair value of available-for-sale investment securities at December 31, 2010 were as follows:

	Amortized Cost		Unrealized Gains		Unrealized Losses			Fair Value
U.S. Treasury and agency debt securities	$	339,982	$	994	$	(592	)	$	340,384
Corporate and other debt securities		122,137		835		(63	)		122,909
Asset-backed securities		33,258		33		(137	)		33,154
Municipal debt securities		41,802		2		(149	)		41,655
Foreign government debt securities		7,844		83		(1	)		7,926
Total available-for-sale investment securities	$	545,023	$	1,947	$	(942	)	$	546,028

Available-For-Sale Securities In A Continuous Unrealized Loss Position

The fair value and related unrealized losses of available-for-sale investment securities in a continuous unrealized loss position for less than 12 months and for 12 months or longer were as follows as of September 30, 2011:

	Less than 12 Months					12 Months or More					Total
	Fair Value		Unrealized Losses			Fair Value		Unrealized Losses			Fair Value		Unrealized Losses
U.S. Treasury and agency debt securities	$	126,897	$	(330	)	$	—	$	—		$	126,897	$	(330	)
Corporate and other debt securities		87,974		(585	)		—		—			87,974		(585	)
Asset-backed securities		50,255		(141	)		827		(10	)		51,082		(151	)
Municipal debt securities		8,472		(28	)		2,039		(93	)		10,511		(121	)
Foreign government debt securities		1,514		(2	)		—		—			1,514		(2	)
Total	$	275,112	$	(1,086	)	$	2,866	$	(103	)	$	277,978	$	(1,189	)

The fair value and related unrealized losses of available-for-sale investment securities in a continuous unrealized loss position for less than 12 months were as follows as of December 31, 2010:

	Fair Value		Unrealized Losses
U.S. Treasury and agency debt securities	$	200,772	$	(592	)
Corporate and other debt securities		16,518		(63	)
Asset-backed securities		17,791		(137	)
Municipal debt securities		25,598		(149	)
Foreign government debt securities		1,203		(1	)
Total	$	261,882	$	(942	)

Contractual Maturities Of Investments In Debt Securities Available-For-Sale

	Amortized Cost		Fair Value
Due within one year	$	67,837	$	67,811
Due after one year through five years		640,566		643,042
Due after five years through ten years		1,066		1,014
Due after ten years		6,300		6,264
Asset-backed securities		97,612		97,661
Total available-for-sale investment securities	$	813,381	$	815,792

Gross Gains (Losses) Realized On Sales, Maturities And Other Securities Transactions Related To Investment Securities

	Three Months Ended September 30,						Nine Months Ended September 30,
	2011			2010			2011			2010
Proceeds from sales of available-for-sale investment securities	$	224,439		$	96,639		$	484,167		$	115,732
Gross gains	$	1,044		$	429		$	2,354		$	511
Gross losses		(93	)		(32	)		(261	)		(88	)
Net gains on sales of available-for-sale securities	$	951		$	397		$	2,093		$	423