| Cash, Cash Equivalents and Short-term Investments |
Cash, cash equivalents and short-term investments consisted of the following as of December 1, 2017 (in thousands): | | | | | | | | | | | | | | | | | | Amortized Cost | | Unrealized Gains | | Unrealized Losses | | Estimated Fair Value | Current assets: | | | | | | | | Cash | $ | 280,488 |
| | $ | — |
| | $ | — |
| | $ | 280,488 |
| Cash equivalents: | | | | | | | | Money market mutual funds | 2,006,741 |
| | — |
| | — |
| | 2,006,741 |
| Time deposits | 18,843 |
| | — |
| | — |
| | 18,843 |
| Total cash equivalents | 2,025,584 |
| | — |
| | — |
| | 2,025,584 |
| Total cash and cash equivalents | 2,306,072 |
| | — |
| | — |
| | 2,306,072 |
| Short-term fixed income securities: | | | | | | | | Asset-backed securities | 98,403 |
| | 1 |
| | (403 | ) | | 98,001 |
| Corporate bonds and commercial paper | 2,461,691 |
| | 2,694 |
| | (10,125 | ) | | 2,454,260 |
| Foreign government securities | 2,396 |
| | — |
| | (8 | ) | | 2,388 |
| Municipal securities | 21,189 |
| | 8 |
| | (132 | ) | | 21,065 |
| U.S. Treasury securities | 941,538 |
| | 2 |
| | (3,552 | ) | | 937,988 |
| Total short-term investments | 3,525,217 |
| | 2,705 |
| | (14,220 | ) | | 3,513,702 |
| Total cash, cash equivalents and short-term investments | $ | 5,831,289 |
| | $ | 2,705 |
| | $ | (14,220 | ) | | $ | 5,819,774 |
|
Cash, cash equivalents and short-term investments consisted of the following as of December 2, 2016 (in thousands): | | | | | | | | | | | | | | | | | | Amortized Cost | | Unrealized Gains | | Unrealized Losses | | Estimated Fair Value | Current assets: | | | | | | | | Cash | $ | 208,635 |
| | $ | — |
| | $ | — |
| | $ | 208,635 |
| Cash equivalents: | |
| | | | | | |
| Corporate bonds and commercial paper | 1,249 |
| | — |
| | — |
| | 1,249 |
| Money market mutual funds | 782,210 |
| | — |
| | — |
| | 782,210 |
| Municipal securities | 1,301 |
| | — |
| | — |
| | 1,301 |
| Time deposits | 17,920 |
| | — |
| | — |
| | 17,920 |
| Total cash equivalents | 802,680 |
| | — |
| | — |
| | 802,680 |
| Total cash and cash equivalents | 1,011,315 |
| | — |
| | — |
| | 1,011,315 |
| Short-term fixed income securities: | | | | | | | |
| Asset backed securities | 111,009 |
| | 95 |
| | (190 | ) | | 110,914 |
| Corporate bonds and commercial paper | 2,464,769 |
| | 3,135 |
| | (9,554 | ) | | 2,458,350 |
| Municipal securities | 134,710 |
| | 37 |
| | (525 | ) | | 134,222 |
| U.S. agency securities | 39,538 |
| | 42 |
| | — |
| | 39,580 |
| U.S. Treasury securities | 1,008,195 |
| | 194 |
| | (1,470 | ) | | 1,006,919 |
| Total short-term investments | 3,758,221 |
| | 3,503 |
| | (11,739 | ) | | 3,749,985 |
| Total cash, cash equivalents and short-term investments | $ | 4,769,536 |
| | $ | 3,503 |
| | $ | (11,739 | ) | | $ | 4,761,300 |
|
|
| Continuous Unrealized Loss Position Less Than Twelve Months Related to Available-for-Sale Securities |
The following table summarizes the fair value and gross unrealized losses related to available-for-sale securities, aggregated by investment category, that have been in an unrealized loss position for less than twelve months, as of December 1, 2017 and December 2, 2016 (in thousands): | | | | | | | | | | | | | | | | | | 2017 | | 2016 | | Fair Value | | Gross Unrealized Losses | | Fair Value | | Gross Unrealized Losses | Corporate bonds and commercial paper | $ | 1,338,232 |
| | $ | (5,459 | ) | | $ | 1,282,076 |
| | $ | (9,474 | ) | Asset-backed securities | 64,618 |
| | (193 | ) | | 54,063 |
| | (189 | ) | Municipal securities | 11,805 |
| | (115 | ) | | 114,810 |
| | (525 | ) | Foreign government securities | 2,388 |
| | (8 | ) | | — |
| | — |
| U.S. Treasury and agency securities | 593,296 |
| | (2,087 | ) | | 580,529 |
| | (1,470 | ) | Total | $ | 2,010,339 |
| | $ | (7,862 | ) | | $ | 2,031,478 |
| | $ | (11,658 | ) |
|
| Cost and Estimated Fair Value of Debt Securities |
The following table summarizes the cost and estimated fair value of short-term fixed income securities classified as short-term investments based on stated effective maturities as of December 1, 2017 (in thousands): | | | | | | | | | | Amortized Cost | | Estimated Fair Value | Due within one year | $ | 1,025,894 |
| | $ | 1,023,639 |
| Due between one and two years | 1,294,919 |
| | 1,289,307 |
| Due between two and three years | 815,254 |
| | 812,828 |
| Due after three years | 389,150 |
| | 387,928 |
| Total | $ | 3,525,217 |
| | $ | 3,513,702 |
|
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