| Schedule of Marketable Debt Securities |
The following is a summary of our available-for-sale debt securities recorded within short-term and long-term investments on the condensed consolidated balance sheets (in thousands): | | | | | | | | | | | | | | | | | | | | | | | | | | June 30, 2020 | | | | | | | | | Amortized Cost | | Gross Unrealized Gains | | Gross Unrealized Losses | | Estimated Fair Value | | Available-for-sale securities: | | | | | | | | | Commercial paper | $ | 414,613 | | | $ | 521 | | | $ | (31) | | | $ | 415,103 | | | Corporate notes and bonds | 1,571,083 | | | 15,645 | | | (493) | | | 1,586,235 | | | Certificates of deposit | 20,077 | | | 21 | | | — | | | 20,098 | | | U.S. government and agency securities | 259,097 | | | 1,641 | | | (5) | | | 260,733 | | | | | | | | | | | Total available-for-sale securities | $ | 2,264,870 | | | $ | 17,828 | | | $ | (529) | | | $ | 2,282,169 | |
| | | | | | | | | | | | | | | | | | | | | | | | | | December 31, 2019 | | | | | | | | Amortized Cost | | Gross Unrealized Gains | | Gross Unrealized Losses | | Estimated Fair Value | | Available-for-sale securities: | | | | | | | | | Commercial paper | $ | 101,416 | | | $ | 83 | | | $ | (9) | | | $ | 101,490 | | | Corporate notes and bonds | 1,654,166 | | | 7,360 | | | (196) | | | 1,661,330 | | | Certificates of deposit | 38,007 | | | 38 | | | — | | | 38,045 | | | U.S. government and agency securities | 127,544 | | | 254 | | | (14) | | | 127,784 | | | Total available-for-sale securities | $ | 1,921,133 | | | $ | 7,735 | | | $ | (219) | | | $ | 1,928,649 | |
|
| Investments Classified by Contractual Maturity Date |
The fair values of available-for-sale securities, by remaining contractual maturity, are as follows (in thousands): | | | | | | | June 30, 2020 | | Due within 1 year | $ | 1,505,362 | | | Due in 1 year through 5 years | 776,807 | | | Total | $ | 2,282,169 | |
|
| Fair Values and Gross Unrealized Losses of Available-for-Sale Securities Aggregated by Investment Category |
The following table shows the fair values and the gross unrealized losses of these available-for-sale debt securities, classified by the length of time that the securities have been in a continuous unrealized loss position, and aggregated by investment types, excluding those securities classified within cash and cash equivalents on the condensed consolidated balance sheets (in thousands): | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | June 30, 2020 | | | | | | | | | | | | | Less than 12 Months | | | | 12 Months or Greater | | | | Total | | | | | Fair Value | | Gross Unrealized Losses | | Fair Value | | Gross Unrealized Losses | | Fair Value | | Gross Unrealized Losses | | Commercial paper | $ | 82,317 | | | $ | (31) | | | $ | — | | | $ | — | | | $ | 82,317 | | | $ | (31) | | | Corporate notes and bonds | 273,570 | | | (493) | | | — | | | — | | | 273,570 | | | (493) | | | | | | | | | | | | | | | U.S. government and agency securities | 72,843 | | | (5) | | | — | | | — | | | 72,843 | | | (5) | | | Total | $ | 428,730 | | | $ | (529) | | | $ | — | | | $ | — | | | $ | 428,730 | | | $ | (529) | |
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | December 31, 2019 | | | | | | | | | | | | Less than 12 Months | | | | 12 Months or Greater | | | | Total | | | | | Fair Value | | Gross Unrealized Losses | | Fair Value | | Gross Unrealized Losses | | Fair Value | | Gross Unrealized Losses | | Commercial paper | $ | 20,752 | | | $ | (9) | | | $ | — | | | $ | — | | | $ | 20,752 | | | $ | (9) | | | Corporate notes and bonds | 242,012 | | | (181) | | | 16,264 | | | (15) | | | 258,276 | | | (196) | | | | | | | | | | | | | | | U.S. government and agency securities | 17,806 | | | (14) | | | — | | | — | | | 17,806 | | | (14) | | | Total | $ | 280,570 | | | $ | (204) | | | $ | 16,264 | | | $ | (15) | | | $ | 296,834 | | | $ | (219) | |
|