Investments	9 Months Ended
Sep. 30, 2018
Investments in privately-held companies [Abstract]
Investments	5. Investments Investments in Privately-Held Companies We adopted ASU 2016-01 in the three months ended March 31, 2018 (refer to Note 1). As of September 30, 2018 and December 31, 2017, we held non-marketable equity investments of approximately $35.0 million and $36.1 million, respectively, in privately-held companies. These investments do not have readily determinable fair values and are measured using the measurement alternative. As of September 30, 2018, $27.0 million of the total investment amount of $35.0 million was re-measured as further described below, and are classified within Level III of the fair value hierarchy. Prior to 2018, we did not record any impairment losses for these investments. During the three months ended September 30, 2018, no impairment or adjustment was recorded. During the nine months ended September 30, 2018, we recorded $1.2 million of unrealized gain on investments in one company after they were re-measured to fair value as of the date observable transactions occurred. In addition, during the nine months ended September 30, 2018, we recorded $10.3 million of impairment loss on an investment. The unrealized gain and loss are classified in “Other income (expense), net” in our accompanying unaudited condensed consolidated statements of operations.

5. Investments

Investments in Privately-Held Companies

We adopted ASU 2016-01 in the three months ended March 31, 2018 (refer to Note 1). As of September 30, 2018 and December 31, 2017, we held non-marketable equity investments of approximately $35.0 million and $36.1 million, respectively, in privately-held companies. These investments do not have readily determinable fair values and are measured using the measurement alternative. As of September 30, 2018, $27.0 million of the total investment amount of $35.0 million was re-measured as further described below, and are classified within Level III of the fair value hierarchy.

Prior to 2018, we did not record any impairment losses for these investments. During the three months ended September 30, 2018, no impairment or adjustment was recorded. During the nine months ended September 30, 2018, we recorded $1.2 million of unrealized gain on investments in one company after they were re-measured to fair value as of the date observable transactions occurred. In addition, during the nine months ended September 30, 2018, we recorded $10.3 million of impairment loss on an investment. The unrealized gain and loss are classified in “Other income (expense), net” in our accompanying unaudited condensed consolidated statements of operations.