Marketable Securities (Tables)

12 Months Ended

Dec. 31, 2013

Investments Debt And Equity Securities [Abstract]

Schedule of Available-For-Sale Securities, All of Which Have Maturities of Twelve Months or Less

Available-for-sale securities, all of which have maturities of twelve months or less, as of December 31, 2013 consisted of the following:

	Amortized Cost		Unrealized Gains		Unrealized Losses			Fair Value
	(in thousands)
December 31, 2013:
Commercial paper	$	49,685	$	—	$	(5	)	$	49,680
Corporate debt securities		40,455		—		(19	)		40,436
Total	$	90,140	$	—	$	(24	)	$	90,116

Schedule of Marketable Securities in an Unrealized Loss Position

Available-for-sale securities in an unrealized loss position as of December 31, 2013 consisted of the following:

	Aggregate		Unrealized
	Fair Value		Losses
	(in thousands)
December 31, 2013:
Commercial paper	$	36,683	$	(5	)
Corporate debt securities		40,436		(19	)
	$	77,119	$	(24	)