Financial Instruments	6 Months Ended
Financial Instruments	Jun. 30, 2016
Fair Value Disclosures [Abstract]
Financial Instruments	7. Financial Instruments Fair Value of Financial Instruments We consider the recorded value of certain financial assets and liabilities, which consist primarily of cash equivalents, accounts receivable and accounts payable, to approximate the fair value of the respective assets and liabilities at June 30, 2016 and December 31, 2015, based on the short-term nature of the assets and liabilities. The fair value of our long-term debt at June 30, 2016 was $516.5 million compared to a carrying value of $500.0 million. At December 31, 2015, the fair value of our long-term debt was $513.5 million compared to a carrying value of $500.0 million. We determine the fair value of our long-term debt primarily based on quoted market prices for our 6% Senior Notes Due 2022 (“2022 Notes”). The fair value of our borrowings on our $550.0 million senior secured bank revolving credit facility (“Senior Bank Credit Facility”) approximates the carrying amount. The fair value of our long-term debt is classified within Level 2 of the fair value hierarchy, because it is traded in less active markets. We estimate the fair value of acquisition-related contingent consideration based on the present value of the consideration expected to be paid during the remainder of the earn-out period, based on management’s assessment of the acquired operations’ forecasted earnings. This fair value measure is based on significant inputs not observed in the market and thus represents a Level 3 measurement. The significant unobservable inputs used in the fair value measurements of our acquisition-related contingent consideration include our measures of the future profitability and related cash flows of the acquired business or assets, impacted by appropriate discount rates. Significant increases (decreases) in any of these inputs in isolation would result in a significantly lower (higher) fair value measurement. Generally, a change in the assumptions used for the discount rates is accompanied by a directionally opposite change in the fair value measurement and a change in the assumptions used for the future cash flows is accompanied by a directionally similar change in the fair value measurement. The fair value of the contingent consideration is reassessed on a quarterly basis by the Company using additional information as it becomes available. Any change in the fair value of an acquisition’s contingent consideration liability results in a remeasurement gain or loss that is recorded as income or expense, respectively, and is included in “Acquisition-related contingent consideration” on the Condensed Consolidated Statements of Comprehensive Income. There was no remeasurement gain or loss recorded during the three months ended June 30, 2016. During the six months ended June 30, 2016, we recorded a $1.0 million expense related to the increase in the liability for future expected contingent consideration payments, driven by improved business results in the current period as well as expected results during the remainder of the earn-out period. During the three and six months ended June 30, 2015, we recorded a $1.7 million gain related to the change in fair value of future contingent consideration payments, of which $1.5 million related to a termination of a contingent consideration arrangement for which no future payments will be made.

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.