Fair Value Measurements | 4. Fair Value Measurements We utilize valuation techniques that maximize the use of observable inputs and minimize the use of unobservable inputs to the extent possible. We determine fair value based on assumptions that market participants would use in pricing an asset or liability in the principal or most advantageous market. When considering market participant assumptions in fair value measurements, the following fair value hierarchy distinguishes between observable and unobservable inputs, which are categorized in one of the following levels: Level 1 Unadjusted quoted prices in active markets for identical assets or liabilities at the Level 2 Inputs other than Level 1 that are observable, either directly or indirectly, such as quoted prices for similar assets or liabilities; quoted prices in markets that are not active near the measurement date; or other inputs that are observable or can be corroborated by observable market data for substantially the full term of the assets or liabilities. Level 3 Unobservable inputs that are supported by little or no market activity and that are significant to the fair value of the assets or liabilities. The fair value of our money market funds was determined based on “Level 1” inputs. The fair value of certificates of deposit, U.S. Treasury and agency bonds, and corporate bonds were determined based on “Level 2” inputs. The valuation techniques used to measure the fair value of certificates of deposit included observable market-based inputs for similar assets, which primarily include yield curves and time-to-maturity two-sided There were no marketable securities measured on a recurring basis in the “Level 3” category. We have not elected the fair value option as prescribed by ASC 825, The Fair Value Option for Financial Assets and Financial Liabilities Instruments Measured at Fair Value on a Recurring Basis. As of June 30, 2017 Gross Cash and Unrealized Cash Short-term Long-term Cost Gains (Losses) Fair Value Equivalents Investments Investments Cash $ 89,576 $ — $ 89,576 $ 89,576 $ — $ — Level 1: Money market funds 5,840 — 5,840 5,840 — — Subtotal 5,840 — 5,840 5,840 — — Level 2: Certificates of deposit 5,894 — 5,894 — 5,894 — U.S. Treasury and agency bonds 53,554 (65 ) 53,489 2,999 20,477 30,013 Corporate bonds 27,947 (30 ) 27,917 — 27,917 — Subtotal 87,395 (95 ) 87,300 2,999 54,288 30,013 Level 3 — — — — — — Total $ 182,811 $ (95 ) $ 182,716 $ 98,415 $ 54,288 $ 30,013 As of December 31, 2016 Gross Cash and Unrealized Cash Short-term Long-term Cost Gains (Losses) Fair Value Equivalents Investments Investments Cash $ 10,499 $ — $ 10,499 $ 10,499 $ — $ — Level 1: Money market funds 20,807 — 20,807 20,807 — — Subtotal 20,807 — 20,807 20,807 — — Level 2: — Certificates of deposit 10,552 — 10,552 — 10,552 — Corporate bonds 10,770 72 10,842 — 10,842 — Subtotal 21,322 72 21,394 — 21,394 — Level 3 — — — — — — Total $ 52,628 $ 72 $ 52,700 $ 31,306 $ 21,394 $ — There were no transfers between Level 1, Level 2, or Level 3 securities during the six months ended June 30, 2017. As of June 30, 2017, there were 23 securities with a fair value of $73.8 million in an unrealized loss position for less than 12 months. The gross unrealized losses of $0.1 million as of June 30, 2017 were due to changes in market rates, and we have determined the losses are temporary in nature. All the long-term investments had maturities of between one and two years in duration as of June 30, 2017. Cash and cash equivalents, restricted cash, and investments as of June 30, 2017 and December 31, 2016 held domestically were approximately $177.7 million and $52.9 million, respectively. Contingent Consideration. earn-out The following table presents a reconciliation of the beginning and ending balances of acquisition-related accrued contingent consideration using significant unobservable inputs (Level 3) for the three and six months ended June 30, 2017 (in thousands): Three Months Ended Six Months Ended June 30, June 30, 2017 2016 2017 2016 Beginning balance $ 1,160 $ — $ — $ — Obligations assumed — — 1,160 — Change in fair value 158 — 158 — Ending balance $ 1,318 $ — $ 1,318 $ — Instruments Not Recorded at Fair Value on a Recurring Basis. Assets and Liabilities Recorded at Fair Value on a Non-Recurring non-recurring |