Fair Value Measurement	12 Months Ended
Fair Value Measurement	Dec. 31, 2011
Fair Value Measurement [Abstract]
Fair Value Measurement	NOTE 9. Fair Value Measurement The carrying value of cash and cash equivalents, accounts receivable and accounts payable approximated fair value as of December 31, 2011 and 2010 due to their short-term nature. Cash and cash equivalents included $42.5 million and $114.6 million as of December 31, 2011 and 2010, respectively, invested in a money market fund comprised of U.S. treasury securities and repurchase agreements for these securities. Restricted investments included $14.3 million and $11.4 million as of December 31, 2011 and 2010, respectively, of mutual funds which are reported at fair value. The fair value measurement of these securities is based on quoted prices in active markets for identical assets which are defined as "Level 1" of the fair value hierarchy in the Fair Value Measurements and Disclosures Topic of the Codification.

The entire disclosure for the fair value of financial instruments (as defined), including financial assets and financial liabilities (collectively, as defined), and the measurements of those instruments as well as disclosures related to the fair value of non-financial assets and liabilities. Such disclosures about the financial instruments, assets, and liabilities would include: (1) the fair value of the required items together with their carrying amounts (as appropriate); (2) for items for which it is not practicable to estimate fair value, disclosure would include: (a) information pertinent to estimating fair value (including, carrying amount, effective interest rate, and maturity, and (b) the reasons why it is not practicable to estimate fair value; (3) significant concentrations of credit risk including: (a) information about the activity, region, or economic characteristics identifying a concentration, (b) the maximum amount of loss the entity is exposed to based on the gross fair value of the related item, (c) policy for requiring collateral or other security and information as to accessing such collateral or security, and (d) the nature and brief description of such collateral or security; (4) quantitative information about market risks and how such risks are managed; (5) for items measured on both a recurring and nonrecurring basis information regarding the inputs used to develop the fair value measurement; and (6) for items presented in the financial statement for which fair value measurement is elected: (a) information necessary to understand the reasons for the election, (b) discussion of the effect of fair value changes on earnings, (c) a description of [similar groups] items for which the election is made and the relation thereof to the balance sheet, the aggregate carrying value of items included in the balance sheet that are not eligible for the election; (7) all other required (as defined) and desired information.

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