Fair Value Measurements (Details) (Recurring basis [Member], USD $) In Thousands, unless otherwise specified	Sep. 30, 2012	Dec. 31, 2011
Cash equivalents:
Total cash equivalents	$ 4,875	$ 7,077
Short-term investments:
Total short-term investments	11,782	9,619
Total assets measured at fair value	17,532	17,571
MPC earn-out liability	632	766
Money market funds [Member]
Cash equivalents:
Total cash equivalents	4,425	6,576
Short-term investments:
Restricted cash-money market fund	875	875
Corporate debt [Member]
Cash equivalents:
Total cash equivalents	450	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	355	355
Corporate commercial paper [Member]
Short-term investments:
Total short-term investments	5,373	1,250
Foreign government bonds [Member]
Short-term investments:
Total short-term investments		500
Corporate debt [Member]
Short-term investments:
Total short-term investments	6,054	5,763
Quoted Prices in Active Markets for Identical Assets (Level 1) [Member]
Cash equivalents:
Total cash equivalents	4,425	6,576
Short-term investments:
Total assets measured at fair value	5,300	7,451
Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] \| Money market funds [Member]
Cash equivalents:
Total cash equivalents	4,425	6,576
Short-term investments:
Restricted cash-money market fund	875	875
Direct or Indirect Observable Inputs (Level 2) [Member]
Cash equivalents:
Total cash equivalents	450	501
Short-term investments:
Total short-term investments	11,782	9,619
Total assets measured at fair value	12,232	10,120
Direct or Indirect Observable Inputs (Level 2) [Member] \| Corporate debt [Member]
Cash equivalents:
Total cash equivalents	450	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	355	355
Direct or Indirect Observable Inputs (Level 2) [Member] \| Corporate commercial paper [Member]
Short-term investments:
Total short-term investments	5,373	1,250
Direct or Indirect Observable Inputs (Level 2) [Member] \| Foreign government bonds [Member]
Short-term investments:
Total short-term investments		500
Direct or Indirect Observable Inputs (Level 2) [Member] \| Corporate debt [Member]
Short-term investments:
Total short-term investments	6,054	5,763
Significant Unobservable Inputs (Level 3) [Member]
Short-term investments:
MPC earn-out liability	$ 632	$ 766

This element represents the portion of the balance sheet assertion valued at fair value by the entity whether such amount is presented as a separate caption or as a parenthetical disclosure. Additionally, this element may be used in connection with the fair value disclosures required in the footnote disclosures to the financial statements. The element may be used in both the balance sheet and disclosure in the same submission. This item includes currency on hand as well as demand deposits with banks or financial institutions. It also includes other kinds of accounts that have the general characteristics of demand deposits in that the Company may deposit additional funds at any time and also effectively may withdraw funds at any time without prior notice or penalty. Cash equivalents, excluding items classified as marketable securities, include short-term, highly liquid investments that are both readily convertible to known amounts of cash, and so near their maturity that they present minimal risk of changes in value because of changes in interest rates. Generally, only investments with original maturities of three months or less qualify under that definition. Original maturity means original maturity to the entity holding the investment. For example, both a three-month US Treasury bill and a three-year Treasury note purchased three months from maturity qualify as cash equivalents. However, a Treasury note purchased three years ago does not become a cash equivalent when its remaining maturity is three months.

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The carrying amounts of cash and cash equivalent items which are restricted as to withdrawal or usage. Restrictions may include legally restricted deposits held as compensating balances against short-term borrowing arrangements, contracts entered into with others, or entity statements of intention with regard to particular deposits; however, time deposits and short-term certificates of deposit are not generally included in legally restricted deposits. Excludes compensating balance arrangements that are not agreements which legally restrict the use of cash amounts shown on the balance sheet. For a classified balance sheet represents the current portion only (the noncurrent portion has a separate concept); there is a separate and distinct element for unclassified presentations.

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