Cash and Cash Equivalents and Marketable Securities (Tables)

3 Months Ended

Mar. 31, 2013

Cash and Cash Equivalents and Marketable Securities [Abstract]

Unrealized gains and losses related to marketable investments and long-term investments

The following tables summarize unrealized gains and losses related to our marketable investments, designated as available-for-sale (in thousands):

March 31, 2013	Amortized Cost		Gross Unrealized Gains			Gross Unrealized Losses			Fair Market Value
Cash and cash equivalents:
Cash	$	1,740		$	—	$	—		$	1,740
Money market funds		12,333			—		—			12,333
Commercial paper		3,199			—		—			3,199
Total cash and cash equivalents		17,272			—		—			17,272
Marketable securities:
U.S. government notes		4,001			5		—			4,006
U.S. government agencies		32,249			44		(1	)		32,292
Municipal securities		5,467			17		(2	)		5,482
Commercial paper		10,958			7		(1	)		10,964
Corporate debt securities		18,011			70		(4	)		18,077
Total marketable investments		70,686			143		(8	)		70,821
Total cash, cash equivalents and marketable investments	$	87,958		$	143	$	(8	)	$	88,093

December 31, 2012	Amortized Cost		Gross Unrealized Gains			Gross Unrealized Losses			Fair Market Value
Cash and cash equivalents:
Cash	$	2,198		$	—	$	—		$	2,198
Money market funds		17,438			—		—			17,348
Commercial paper		4,000			—		—			4,000
Total cash and cash equivalents		23,546			—		—			23,546
Marketable securities:
U.S. government notes		4,005			4		—			4,009
U.S. government agencies		24,910			48		—			24,958
Municipal securities		4,184			23		(1	)		4,206
Commercial paper		10,515			4		—			10,519
Corporate debt securities		18,281			59		(6	)		18,334
Total marketable investments		61,895			138		(7	)		62,026
Total cash, cash equivalents and marketable investments	$	85,441		$	138	$	(7	)	$	85,572

Estimated fair value of marketable investments and long-term investments classified by contractual maturity date

The following table summarizes the estimated fair value of our securities available-for-sale and classified as cash and cash equivalents and marketable investments classified by the contractual maturity date of the security as of March 31, 2013 (in thousands):

	Amount
Due in less than one year	$	39,455
Due in 1 to 3 years		34,565
Due in 3 to 10 years		—
Due in greater than 10 years		—
	$	74,020