Fair Value Measurements (Tables)

12 Months Ended

Dec. 31, 2012

Fair Value Measurements [Abstract]

Assets and liabilities measured at fair value on a recurring basis

Assets and liabilities measured at fair value on a recurring basis are summarized below (in thousands):

	December 31, 2012
	Quoted Prices in Active Markets for Identical Assets (Level 1)		Direct or Indirect Observable Inputs (Level 2)		Significant Unobservable Inputs (Level 3)		Total
Assets
Cash equivalents:
Money market funds	$	7,313	$	—	$	—	$	7,313
Corporate debt		—		—		—		—
Total cash equivalents		7,313		—		—		7,313
Short-term investments:
U.S. agency securities		—		—		—		—
Municipal securities		—		356		—		356
Corporate commercial paper		—		4,374		—		4,374
Foreign government bonds		—		999		—		999
Corporate debt securities		—		4,097		—		4,097
Total short-term investments		—		9,826	$	—		9,826
Restricted cash—money market fund		875		—		—		875
Total assets	$	8,188	$	9,826	$	—	$	18,014

	December 31, 2011
	Quoted Prices in Active Markets for Identical Assets (Level 1)		Direct or Indirect Observable Inputs (Level 2)		Significant Unobservable Inputs (Level 3)		Total
Assets
Cash equivalents:
Money market funds	$	6,576	$	—	$	—	$	6,576
Corporate debt		—		501		—		501
Total cash equivalents		6,576		501		—		7,077
Short-term investments:
U.S. agency securities		—		1,751		—		1,751
Municipal securities		—		355		—		355
Corporate commercial paper		—		1,250		—		1,250
Foreign government bonds		—		500		—		500
Corporate debt securities		—		5,763		—		5,763
Total short-term investments		—		9,619	$	—		9,619
Restricted cash—money market fund		875		—		—		875
Total assets	$	7,451	$	10,120	$	—	$	17,571
MPC earn-out liability	$	—	$	—	$	766	$	766