v3.10.0.1

Investments (Tables) | 9 Months Ended
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Sep. 30, 2018
Investments [Abstract] |
Fair value of short and long-term investments classified as available for sale | The following tables summarize the unrealized gains and losses and estimated fair value of our investments classified as available-for-sale as of September 30, 2018 and December 31, 2017 (in millions):
| September 30, 2018
| Gross Amortized Cost |  | Gross Unrealized Gains |  | Gross Unrealized Losses |  | Estimated Fair Value
Short-term investments: |  |  |  |  |  |  |
Restricted cash | $ | 15 |  |  | $ | — |  |  | $ | — |  |  | $ | 15 |
Corporate debt securities | 2,702 |  |  | 1 |  |  | (7 | ) |  | 2,696 |
Government and agency securities | 41 |  |  | — |  |  | — |  |  | 41 |
| $ | 2,758 |  |  | $ | 1 |  |  | $ | (7 | ) |  | $ | 2,752 |
Long-term investments: |  |  |  |  |  |  |
Corporate debt securities | 4,171 |  |  | 7 |  |  | (46 | ) |  | 4,132 |
| $ | 4,171 |  |  | $ | 7 |  |  | $ | (46 | ) |  | $ | 4,132 |
| December 31, 2017
| Gross Amortized Cost |  | Gross Unrealized Gains |  | Gross Unrealized Losses |  | Estimated Fair Value
Short-term investments: |  |  |  |  |  |  |
Restricted cash | $ | 20 |  |  | $ | — |  |  | $ | — |  |  | $ | 20 |
Corporate debt securities | 3,726 |  |  | 1 |  |  | (4 | ) |  | 3,723 |
| $ | 3,746 |  |  | $ | 1 |  |  | $ | (4 | ) |  | $ | 3,743 |
Long-term investments: |  |  |  |  |  |  |
Corporate debt securities | 5,458 |  |  | 12 |  |  | (24 | ) |  | 5,446 |
| $ | 5,458 |  |  | $ | 12 |  |  | $ | (24 | ) |  | $ | 5,446 |
Estimated fair values of short and long-term investments classified by date of contractual maturity | The estimated fair values of our short-term and long-term investments classified as available-for-sale by date of contractual maturity as of September 30, 2018 are as follows (in millions):
| September 30, 2018
One year or less (including restricted cash of $15) | $ | 2,752 |
One year through two years | 1,973 |
Two years through three years | 1,451 |
Three years through four years | 591 |
Four years through five years | 117 |
| $ | 6,884 |
Schedule of Equity Method Investments | The following table provides a summary of our equity investments as of September 30, 2018 and December 31, 2017 (in millions):
| September 30, 2018 |  | December 31, 2017
Equity investments without readily determinable fair values | $ | 138 |  |  | $ | 872 |
Equity investments under the equity method of accounting | 6 |  |  | 13 |
Total equity investments | $ | 144 |  |  | $ | 885 |
Schedule of Unrealized Gains (Losses) on Equity Investments | The following table provides a summary of unrealized gains and losses recorded in interest and other, net during the three and nine months ended September 30, 2018 related to equity investments without readily determinable fair values still held at September 30, 2018.
| Three Months Ended September 30, 2018 |  | Nine Months Ended September 30, 2018
Net gains/(losses) recognized during the period on equity investments | $ | 313 |  |  | $ | 313 |
Less: Net gains/(losses) recognized during the period on equity investments sold during the period | (313 | ) |  | (313 | )
Total unrealized gains/(losses) on equity investments still held at September 30, 2018 | $ | — |  |  | $ | — |
Schedule of Equity Securities without Readily Determinable Fair Value | The following table summarizes the total carrying value of equity investments without readily determinable fair values during the three and nine months ended September 30, 2018 (in millions):
| Three Months Ended September 30, 2018 |  | Nine Months Ended September 30, 2018
Carrying value, beginning of period | $ | 859 |  |  | $ | 872 |
Additions | — |  |  | 23 |
Sales | (718 | ) |  | (718 | )
Downward adjustments for observable price changes and impairment | — |  |  | (20 | )
Foreign currency translation and other | (3 | ) |  | (19 | )
Carrying value, end of period | $ | 138 |  |  | $ | 138 |

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