Marketable Securities (Tables)

3 Months Ended

Sep. 30, 2013

Cash and Cash Equivalents [Abstract]

Summary of cash, cash equivalents and marketable securities

A summary of the Company’s cash, cash equivalents and marketable securities is shown below:

	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses			Fair Value
	(in thousands)
As of September 30, 2013
Cash and cash equivalents:
Cash and money market funds	$	580,286	$	—	$	—		$	580,286
Government-sponsored enterprise securities	2,895		—		—			2,895
Total cash and cash equivalents	$	583,181	$	—	$	—		$	583,181
Marketable securities:
U.S. Treasury securities (due within 1 year)	$	—	$	—	$	—		$	—
Government-sponsored enterprise securities (due within 1 year)	555,502		35		(10		)	555,527
Commercial paper (due within 1 year)	125,073		191		—			125,264
Corporate debt securities (due within 1 year)	148,672		21		(38		)	148,655
Corporate debt securities (due after 1 year through 5 years)	10,019		5		(1		)	10,023
Total marketable securities	$	839,266	$	252	$	(49	)	$	839,469
Total cash, cash equivalents and marketable securities	$	1,422,447	$	252	$	(49	)	$	1,422,650
As of December 31, 2012
Cash and cash equivalents:
Cash and money market funds	$	489,407	$	—	$	—		$	489,407
Government-sponsored enterprise securities	—		—		—			—
Total cash and cash equivalents	$	489,407	$	—	$	—		$	489,407
Marketable securities:
U.S. Treasury securities (due within 1 year)	$	111,350	$	2	$	(2	)	$	111,350
Government-sponsored enterprise securities (due within 1 year)	440,181		49		(5		)	440,225
Commercial paper (due within 1 year)	225,294		155		—			225,449
Corporate debt securities (due within 1 year)	15,429		1		(1		)	15,429
Corporate debt securities (due after 1 year through 5 years)	39,358		10		(13		)	39,355
Total marketable securities	$	831,612	$	217	$	(21	)	$	831,808
Total cash, cash equivalents and marketable securities	$	1,321,019	$	217	$	(21	)	$	1,321,215