Fair Value Measurements (Details) (Recurring basis [Member], USD $) In Thousands, unless otherwise specified	Dec. 31, 2012	Dec. 31, 2011
Cash and cash equivalents:
Total cash equivalents	$ 7,313	$ 7,077
Short-term investments:
Total short-term investments	9,826	9,619
Restricted cash-money market fund		875
Total assets	18,014	17,571
MPC earn-out liability		766
Money market funds [Member]
Cash and cash equivalents:
Total cash equivalents	7,313	6,576
Short-term investments:
Restricted cash-money market fund	875
Corporate debt [Member]
Cash and cash equivalents:
Total cash equivalents		501
U.S. agency securities [Member]
Short-term investments:
Total short-term investments		1,751
Municipal securities [Member]
Short-term investments:
Total short-term investments	356	355
Corporate commercial paper [Member]
Short-term investments:
Total short-term investments	4,374	1,250
Foreign government bonds [Member]
Short-term investments:
Total short-term investments	999	500
Corporate debt securities [Member]
Short-term investments:
Total short-term investments	4,097	5,763
Quoted Prices in Active Markets for Identical Assets (Level 1) [Member]
Cash and cash equivalents:
Total cash equivalents	7,313	6,576
Short-term investments:
Total short-term investments
Restricted cash-money market fund		875
Total assets	8,188	7,451
MPC earn-out liability
Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | Money market funds [Member]
Cash and cash equivalents:
Total cash equivalents	7,313	6,576
Short-term investments:
Restricted cash-money market fund	875
Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | Corporate debt [Member]
Cash and cash equivalents:
Total cash equivalents
Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | U.S. agency securities [Member]
Short-term investments:
Total short-term investments
Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | Municipal securities [Member]
Short-term investments:
Total short-term investments
Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | Corporate commercial paper [Member]
Short-term investments:
Total short-term investments
Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | Foreign government bonds [Member]
Short-term investments:
Total short-term investments
Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | Corporate debt securities [Member]
Short-term investments:
Total short-term investments
Direct or Indirect Observable Inputs (Level 2) [Member]
Cash and cash equivalents:
Total cash equivalents		501
Short-term investments:
Total short-term investments	9,826	9,619
Restricted cash-money market fund
Total assets	9,826	10,120
MPC earn-out liability
Direct or Indirect Observable Inputs (Level 2) [Member] | Money market funds [Member]
Cash and cash equivalents:
Total cash equivalents
Short-term investments:
Restricted cash-money market fund
Direct or Indirect Observable Inputs (Level 2) [Member] | Corporate debt [Member]
Cash and cash equivalents:
Total cash equivalents		501
Direct or Indirect Observable Inputs (Level 2) [Member] | U.S. agency securities [Member]
Short-term investments:
Total short-term investments		1,751
Direct or Indirect Observable Inputs (Level 2) [Member] | Municipal securities [Member]
Short-term investments:
Total short-term investments	356	355
Direct or Indirect Observable Inputs (Level 2) [Member] | Corporate commercial paper [Member]
Short-term investments:
Total short-term investments	4,374	1,250
Direct or Indirect Observable Inputs (Level 2) [Member] | Foreign government bonds [Member]
Short-term investments:
Total short-term investments	999	500
Direct or Indirect Observable Inputs (Level 2) [Member] | Corporate debt securities [Member]
Short-term investments:
Total short-term investments	4,097	5,763
Significant Unobservable Inputs (Level 3) [Member]
Cash and cash equivalents:
Total cash equivalents
Short-term investments:
Total short-term investments
Restricted cash-money market fund
Total assets
MPC earn-out liability		766
Significant Unobservable Inputs (Level 3) [Member] | Money market funds [Member]
Cash and cash equivalents:
Total cash equivalents
Short-term investments:
Restricted cash-money market fund
Significant Unobservable Inputs (Level 3) [Member] | Corporate debt [Member]
Cash and cash equivalents:
Total cash equivalents
Significant Unobservable Inputs (Level 3) [Member] | U.S. agency securities [Member]
Short-term investments:
Total short-term investments
Significant Unobservable Inputs (Level 3) [Member] | Municipal securities [Member]
Short-term investments:
Total short-term investments
Significant Unobservable Inputs (Level 3) [Member] | Corporate commercial paper [Member]
Short-term investments:
Total short-term investments
Significant Unobservable Inputs (Level 3) [Member] | Foreign government bonds [Member]
Short-term investments:
Total short-term investments
Significant Unobservable Inputs (Level 3) [Member] | Corporate debt securities [Member]
Short-term investments:
Total short-term investments