Fair Value Measurements (Tables)

9 Months Ended

Sep. 30, 2012

Fair Value Measurements [Abstract]

Assets and liabilities measured at fair value on a recurring basis

	September 30, 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	$	4,425	$	—	$	—	$	4,425
Corporate debt		—		450		—		450
Total cash equivalents		4,425		450		—		4,875
Short-term investments:
Municipal securities		—		355		—		355
Corporate commercial paper		—		5,373		—		5,373
Corporate debt		—		6,054		—		6,054
Total short-term investments		—		11,782		—		11,782
Restricted cash—money market fund		875		—		—		875
Total assets measured at fair value	$	5,300	$	12,232	$	—	$	17,532
MPC earn-out liability	$	—	$	—	$	632	$	632

	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		—		5,763		—		5,763
Total short-term investments		—		9,619	$	—		9,619
Restricted cash—money market fund		875		—		—		875
Total assets measured at fair value	$	7,451	$	10,120	$	—	$	17,571
MPC earn-out liability	$	—	$	—	$	766	$	766