Fair Value Measurement	12 Months Ended
Fair Value Measurement	Dec. 31, 2017
Fair Value Disclosures [Abstract]
Fair Value Measurement	NOTE 8. Fair Value Measurement The carrying value of cash and cash equivalents, accounts receivable, accounts payable and debt materially approximated fair value as of December 31, 2017 and 2016 due to their short-term nature. We consider as cash equivalents all highly liquid instruments with an original maturity of three months or less. As of December 31, 2017 and 2016, our cash and temporary investments were with high quality financial institutions in (DDAs) Demand Deposit Accounts and Savings Accounts. Restricted investments included $24.2 million and $20.9 million as of December 31, 2017 and 2016, respectively, of mutual funds which are reported at fair value. These investments relate to the nonqualified deferred compensation plan that is described in Note 13. Our assets and liabilities measured at fair value are based on valuation techniques which consider prices and other relevant information generated by market transactions involving identical or comparable assets and liabilities. These valuation methods are based on either quoted market prices (Level 1) or inputs, other than quoted prices in active markets, that are observable either directly or indirectly (Level 2). Cash and cash equivalents, accounts receivable and accounts payable are defined as “Level 1,” while long-term debt is defined as “Level 2” 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.