Short-Term Investments (Tables)

12 Months Ended

Dec. 31, 2012

Summary of Short-Term Investments

The following table summarizes the Company’s short-term investments (in thousands):

	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses			Estimated Fair Value
As of December 31, 2012
Certificates of deposit	$	1,603	$	—	$	—		$	1,603
State, municipal and local government agencies bonds		59,009		45		(4	)		59,050
Corporate bonds		31,568		4		(10	)		31,562
Commercial paper		10,287		1		—			10,288
U.S. federal government bonds		2,003		—		—			2,003
Total short-term investments	$	104,470	$	50	$	(14	)	$	104,506
As of December 31, 2011
State, municipal and local government agencies bonds	$	38,785	$	46	$	(6	)	$	38,825
Corporate bonds		18,613		6		(15	)		18,604
Commercial paper		4,195		—		—			4,195
U.S. federal government bonds		9,226		4		—			9,230
Total short-term investments	$	70,819	$	56	$	(21	)	$	70,854

Maturities of Short-Term Investments

The following table summarizes the maturities of the Company’s short-term investments (in thousands):

	December 31,
	2012		2011
Less than one year	$	76,779	$	43,470
Due in 1 - 2 years		27,727		27,384
Total short-term investments	$	104,506	$	70,854