Investments (Tables)
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12 Months Ended |
Dec. 29, 2017 |
Investments, Debt and Equity Securities [Abstract] |
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Summary of Cash Equivalents and Investments by Security Type |
The amounts presented exclude cash, but include investments classified as cash equivalents (in thousands): | | | | | | | | | | | | | | | | | | December 31, 2017 | | Amortized Cost | | Gross Unrealized Gains | | Gross Unrealized Losses | | Fair Value | Money market funds | $ | 45,478 |
| | $ | — |
| | $ | — |
| | $ | 45,478 |
| Commercial paper | 199,647 |
| | — |
| | — |
| | 199,647 |
| Corporate bonds | 179,336 |
| | 18 |
| | (332 | ) | | 179,022 |
| U.S. Treasury and government sponsored enterprises | 16,295 |
| | — |
| | (32 | ) | | 16,263 |
| Total | $ | 440,756 |
| | $ | 18 |
| | $ | (364 | ) | | $ | 440,410 |
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| | | | | | | | | | | | | | | | | | December 31, 2016 | | Amortized Cost | | Gross Unrealized Gains | | Gross Unrealized Losses | | Fair Value | Money market funds | $ | 71,457 |
| | $ | — |
| | $ | — |
| | $ | 71,457 |
| Commercial paper | 165,375 |
| | — |
| | — |
| | 165,375 |
| Corporate bonds | 152,712 |
| | 3 |
| | (308 | ) | | 152,407 |
| U.S. Treasury and government sponsored enterprises | 70,730 |
| | 11 |
| | (14 | ) | | 70,727 |
| Total | $ | 460,274 |
| | $ | 14 |
| | $ | (322 | ) | | $ | 459,966 |
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Fair Value and Gross Unrealized Losses on Investments |
The fair value and gross unrealized losses of investments available-for-sale in an unrealized loss position were as follows (in thousands): | | | | | | | | | | | | | | | | | | | | | | | | | | December 31, 2017 | | In an Unrealized Loss Position Less than 12 Months | | In an Unrealized Loss Position 12 Months or Greater | | Total | | Fair Value | | Gross Unrealized Losses | | Fair Value | | Gross Unrealized Losses | | Fair Value | | Gross Unrealized Losses | Corporate bonds | $ | 140,746 |
| | $ | (296 | ) | | $ | 20,047 |
| | $ | (36 | ) | | $ | 160,793 |
| | $ | (332 | ) | U.S. Treasury and government sponsored enterprises | 13,611 |
| | (23 | ) | | 2,651 |
| | (9 | ) | | 16,262 |
| | (32 | ) | Total | $ | 154,357 |
| | $ | (319 | ) | | $ | 22,698 |
| | $ | (45 | ) | | $ | 177,055 |
| | $ | (364 | ) |
| | | | | | | | | | | | | | | | | | | | | | | | | | December 31, 2016 | | In an Unrealized Loss Position Less than 12 Months | | In an Unrealized Loss Position 12 Months or Greater | | Total | | Fair Value | | Gross Unrealized Losses | | Fair Value | | Gross Unrealized Losses | | Fair Value | | Gross Unrealized Losses | Corporate bonds | $ | 140,559 |
| | $ | (305 | ) | | $ | 3,001 |
| | $ | (3 | ) | | $ | 143,560 |
| | $ | (308 | ) | U.S. Treasury and government sponsored enterprises | 27,657 |
| | (14 | ) | | — |
| | — |
| | 27,657 |
| | (14 | ) | Commercial paper (1) | 998 |
| | — |
| | — |
| | — |
| | 998 |
| | — |
| Total | $ | 169,214 |
| | $ | (319 | ) | | $ | 3,001 |
| | $ | (3 | ) | | $ | 172,215 |
| | $ | (322 | ) |
____________________ | | (1) | Gross unrealized losses on commercial paper were less than $1 thousand. |
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Summary of Cash Equivalents and Investments by Contractual Maturity |
fair value of cash equivalents and investments by contractual maturity were as follows (in thousands): | | | | | | | | | | December 31, | | 2017 | | 2016 | Maturing in one year or less | $ | 377,155 |
| | $ | 404,365 |
| Maturing after one year through five years | 63,255 |
| | 55,601 |
| Total | $ | 440,410 |
| | $ | 459,966 |
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