FAIR VALUE OF FINANCIAL INSTRUMENTS | FAIR VALUE OF FINANCIAL INSTRUMENTS As of June 30, 2015 and December 31, 2014 , the carrying amounts of cash and cash equivalents, receivables, accounts payable, and accrued expenses approximated their estimated fair values because of the short-term nature of these financial instruments. As of June 30, 2015 , we had $300.0 million outstanding on our term loan facility and we had nothing drawn on our revolving credit facility under the 2015 Senior Credit Facility. As of December 31, 2014 , we had $173.8 million outstanding on our term loan facility and $35.0 million outstanding on our revolving credit facility under the Credit Agreement. Both credit facilities carry a variable interest rate set at current market rates, and as such, the carrying values approximate fair value. Our More Disruption Please (“MDP”) Accelerator portfolio is a program designed to cultivate health care information technology start-ups and expand services offered to our physician network. Certain of these investments as of June 30, 2015 and December 31, 2014 are in the form of short-term convertible notes receivable, and are included in prepaid expenses and other current assets; investments that are not classified as short-term are included in investments and other assets on our Condensed Consolidated Balance Sheets. At June 30, 2015 , as there is no indication of performance risk and no conversion is currently contemplated, we estimate that the fair value of the notes receivable approximate cost, based on inputs including the original transaction price, our own recent transactions in the same or similar instruments, completed or pending third-party transactions in the underlying investments, subsequent rounds of financing, and changes in financial ratios or cash flows (Level 3). Marketable equity securities are valued using a market approach based upon the quoted market prices of identical instruments when available or other observable inputs such as trading prices of identical instruments in inactive markets or similar securities. Our interest rate swap agreement was designed to manage exposure to interest rates on our variable rate indebtedness. We have designated the interest rate swap agreement as a cash flow hedge. For the three and six months ended June 30, 2015 , no amount was recognized in earnings for our interest rate swap. There was no ineffectiveness associated with the interest rate swap during the three and six months ended June 30, 2015 , nor was any amount excluded from ineffectiveness testing. We do not expect that any of the $0.6 million of pre-tax unrealized losses included in accumulated other comprehensive income at June 30, 2015 , will be reclassified into earnings within the next 12 months. This amount will vary due to fluctuations in interest rates. We are exposed to credit loss in the event of non-performance by the swap counterparty. The estimated fair value of our interest rate swap agreement with a certain financial institution at June 30, 2015 and December 31, 2014 was a liability of $0.6 million and $0.2 million , respectively, based on inputs other than quoted prices that are observable for the interest rate swap (Level 2). Inputs include present value of fixed and projected floating rate cash flows over the term of the swap contract. The following table presents information about our financial assets and liabilities that are measured at fair value on a recurring basis as of June 30, 2015 and December 31, 2014 , and indicates the fair value hierarchy of the valuation techniques we utilized to determine such fair value. In general, fair values determined by Level 1 inputs utilize quoted prices (unadjusted) in active markets for identical assets or liabilities, and fair values determined by Level 2 inputs utilize quoted prices (unadjusted) in inactive markets for identical assets or liabilities obtained from readily available pricing sources for similar instruments. The fair values determined by Level 3 inputs are unobservable values which are supported by little or no market activity. It is our policy to recognize transfers between levels of the fair value hierarchy, if any, at the end of the reporting period; however, there have been no such transfers during any of the periods presented. Fair Value Measurements as of June 30, 2015, Using Level 1 Level 2 Level 3 Total Available-for-sale investments: Marketable equity securities $ 9,587 $ — $ — $ 9,587 Debt securities: MDP Accelerator portfolio $ — $ — $ 1,250 $ 1,250 Total assets $ 9,587 $ — $ 1,250 $ 10,837 Interest rate swap liability (a) $ — $ (556 ) $ — $ (556 ) Total liabilities $ — $ (556 ) $ — $ (556 ) Fair Value Measurements as of December 31, 2014, Using Level 1 Level 2 Level 3 Total Available-for-sale investments: Marketable equity securities $ 40,950 $ — $ — $ 40,950 Debt securities: MDP Accelerator portfolio $ — $ — $ 750 $ 750 Total assets $ 40,950 $ — $ 750 $ 41,700 Interest rate swap liability (a) $ — $ (244 ) $ — $ (244 ) Total liabilities $ — $ (244 ) $ — $ (244 ) (a) Recorded in other long-term liabilities on the Condensed Consolidated Balance Sheets. The following table presents our financial instruments measured at fair value using unobservable inputs (Level 3) as of June 30, 2015 : Fair Value Measurements Using Unobservable Inputs (Level 3) Three Months Ended June 30, 2015 Six Months Ended June 30, 2015 Balance, beginning of period $ 750 $ 750 Reductions (250 ) (250 ) Additions 750 750 Balance, end of period $ 1,250 $ 1,250 |