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Financial Instruments and Fair Value Measurements (Tables)
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3 Months Ended |
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Mar. 31, 2015
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| Financial Instruments and Fair Value [Abstract] |
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| Summary of Investments [Table Text Block] |
The following table summarizes our investments as of March 31, 2015 and December 31, 2014 (in thousands): | | | | | | | | | | | | | | | | | | March 31, 2015 | | Amortized Cost | | Unrealized Gains | | Unrealized Losses | | Fair Value | Corporate debt securities | $ | 568,456 |
| | $ | 593 |
| | $ | (243 | ) | | $ | 568,806 |
| Commercial paper | 43,758 |
| | 1 |
| | (9 | ) | | 43,750 |
| Municipal bonds | 49,825 |
| | 21 |
| | (26 | ) | | 49,820 |
| Certificates of deposit and term deposits (1) | 13,080 |
| | — |
| | — |
| | 13,080 |
| U.S. government and agency securities | 10,749 |
| | 8 |
| | — |
| | 10,757 |
| Total available-for-sale securities | $ | 685,868 |
| | $ | 623 |
| | $ | (278 | ) | | $ | 686,213 |
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| | | | | | | | | | | | | | | | | | December 31, 2014 | | Amortized Cost | | Unrealized Gains | | Unrealized Losses | | Fair Value | Corporate debt securities | $ | 589,526 |
| | $ | 365 |
| | $ | (875 | ) | | $ | 589,016 |
| Commercial paper | 51,156 |
| | 3 |
| | (4 | ) | | 51,155 |
| Municipal bonds | 39,745 |
| | 15 |
| | (39 | ) | | 39,721 |
| Certificates of deposit and term deposits (1) | 22,854 |
| | — |
| | — |
| | 22,854 |
| U.S. government and agency securities | 5,749 |
| | 1 |
| | (6 | ) | | 5,744 |
| Total available-for-sale securities | $ | 709,030 |
| | $ | 384 |
| | $ | (924 | ) | | $ | 708,490 |
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(1) The majority of our certificates of deposit and term deposits are foreign deposits. |
| Schedule of Unrealized Loss on Investments [Table Text Block] |
The following table shows the gross unrealized losses and the related fair values of our investments that have been in a continuous unrealized loss position as of March 31, 2015 and December 31, 2014 (in thousands):
| | | | | | | | | | | | | | | | | | | | | | | | | | March 31, 2015 | | Less Than 12 Months | | 12 Months or Greater | | Total | | Fair Value | | Unrealized Losses | | Fair Value | | Unrealized Losses | | Fair Value | | Unrealized Losses | Corporate debt securities | $ | 177,364 |
| | $ | (214 | ) | | $ | 13,142 |
| | $ | (29 | ) | | $ | 190,506 |
| | $ | (243 | ) | Commercial paper | 8,375 |
| | (9 | ) | | — |
| | — |
| | 8,375 |
| | (9 | ) | Municipal bonds | 32,205 |
| | (26 | ) | | — |
| | — |
| | 32,205 |
| | (26 | ) | Total available-for-sale securities | $ | 217,944 |
| | $ | (249 | ) | | $ | 13,142 |
| | $ | (29 | ) | | $ | 231,086 |
| | $ | (278 | ) |
| | | | | | | | | | | | | | | | | | | | | | | | | | December 31, 2014 | | Less Than 12 Months | | 12 Months or Greater | | Total | | Fair Value | | Unrealized Losses | | Fair Value | | Unrealized Losses | | Fair Value | | Unrealized Losses | Corporate debt securities | $ | 317,011 |
| | $ | (858 | ) | | $ | 6,011 |
| | $ | (17 | ) | | $ | 323,022 |
| | $ | (875 | ) | Commercial paper | 8,185 |
| | (4 | ) | | — |
| | — |
| | 8,185 |
| | (4 | ) | Municipal bonds | 26,684 |
| | (39 | ) | | — |
| | — |
| | 26,684 |
| | (39 | ) | U.S. government and agency securities | 4,745 |
| | (6 | ) | | — |
| | — |
| | 4,745 |
| | (6 | ) | Total available-for-sale securities | $ | 356,625 |
| | $ | (907 | ) | | $ | 6,011 |
| | $ | (17 | ) | | $ | 362,636 |
| | $ | (924 | ) |
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| Investments Classified by Contractual Maturity Date [Table Text Block] |
The contractual maturities of our investments as of March 31, 2015 and December 31, 2014 were as follows (in thousands): | | | | | | | | | | March 31,
2015 | | December 31,
2014 | Due within one year | $ | 417,605 |
| | $ | 436,766 |
| Due within one to three years | 268,608 |
| | 271,724 |
| Total | $ | 686,213 |
| | $ | 708,490 |
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| Schedule of Fair Value, Assets and Liabilities Measured on Recurring Basis [Table Text Block] |
The following table presents the fair value of our financial assets and liabilities measured at fair value on a recurring basis as of March 31, 2015 and December 31, 2014 (in thousands): | | | | | | | | | | | | | | | | | | | | | | | | | | | March 31, 2015 | | December 31, 2014 | | | Aggregate Fair Value | | Quoted Prices in Active Markets For Identical Assets | | Significant Other Observable Remaining Inputs | | Aggregate Fair Value | | Quoted Prices in Active Markets For Identical Assets | | Significant Other Observable Remaining Inputs | | | | | (Level 1) | | (Level 2) | | | | (Level 1) | | (Level 2) | | Assets: | | | | | | | | | | | | | Corporate debt securities | $ | 568,806 |
| | $ | — |
| | $ | 568,806 |
| | $ | 589,016 |
| | $ | — |
| | $ | 589,016 |
| | Commercial paper | 43,750 |
| | — |
| | 43,750 |
| | 51,155 |
| | — |
| | 51,155 |
| | Municipal bonds | 49,820 |
| | — |
| | 49,820 |
| | 39,721 |
| | — |
| | 39,721 |
| | Certificates of deposit and term deposits | 13,080 |
| | — |
| | 13,080 |
| | 22,854 |
| | — |
| | 22,854 |
| | Money market funds | 29,154 |
| | 29,154 |
| | — |
| | 13,311 |
| | 13,311 |
| | — |
| | U.S. government and agency securities | 10,757 |
| | 2,001 |
| | 8,756 |
| | 5,744 |
| | 1,998 |
| | 3,746 |
| | Total | $ | 715,367 |
| | $ | 31,155 |
| | $ | 684,212 |
| | $ | 721,801 |
| | $ | 15,309 |
| | $ | 706,492 |
| | | | | | | | | | | | | | | Reported as: | | | | | | | | | | | | | Cash equivalents | $ | 29,154 |
| | | | | | $ | 13,311 |
| | | | | | Short-term investments | 417,605 |
| | | | | | 436,766 |
| | | | | | Long-term investments | 268,608 |
| | | | | | 271,724 |
| | | | | | Total | $ | 715,367 |
| | | | | | $ | 721,801 |
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