| Schedule of Carrying Values and Estimated Fair Values of Debt Instruments |
Net Carrying Amounts of our Convertible Notes The carrying amount and fair value of our Convertible Notes were as follows (in thousands). | | | | | | | | | | | | | | | | | September 30,
2022 | | December 31,
2021 | | Principal amount: | | | | | | 2024 Convertible Notes | | $ | 13,483 | | | $ | 90,936 | | | 2027 Convertible Notes | | 805,000 | | | 805,000 | | | 2028 Convertible Notes | | 720,000 | | | — | | | Total Principal Amount | | $ | 1,538,483 | | | $ | 895,936 | | | | | | | | Unamortized debt discount: | | | | | | 2024 Convertible Notes | | $ | (168) | | | $ | (1,517) | | | 2027 Convertible Notes | | (15,208) | | | (17,745) | | | 2028 Convertible Notes | | (18,636) | | | — | | | Total unamortized debt discount | | $ | (34,012) | | | $ | (19,262) | | | | | | | | Carrying amount: | | | | | | 2024 Convertible Notes | | $ | 13,315 | | | $ | 89,419 | | | 2027 Convertible Notes | | 789,792 | | | 787,255 | | | 2028 Convertible Notes | | 701,364 | | | — | | | Total carrying amount | | $ | 1,504,471 | | | $ | 876,674 | | | | | | | | Fair value based on trading levels (Level 2): | | | | | | 2024 Convertible Notes | | $ | 23,138 | | | $ | 159,678 | | | 2027 Convertible Notes | | 684,226 | | | 718,889 | | | 2028 Convertible Notes | | 678,218 | | | — | | | Total fair value of outstanding notes | | $ | 1,385,582 | | | $ | 878,567 | | | | | | | | Remaining amortization per period of debt discount (in years): | | | | | | 2024 Convertible Notes | | 2.2 | | 2.9 | | 2027 Convertible Notes | | 4.4 | | 5.2 | | 2028 Convertible Notes | | 5.9 | | N/A |
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| Interest Income and Interest Expense Disclosure |
The following table summarizes the components of interest expense and the effective interest rates for each of our Convertible Notes (in thousands). | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Three Months Ended
September 30, | | Nine Months Ended
September 30, | | | 2022 | | 2021 | | 2022 | | 2021 | | Coupon interest: | | | | | | | | | | 2024 Convertible Notes | | $ | 161 | | | $ | 284 | | | $ | 729 | | | $ | 1,621 | | | 2027 Convertible Notes | | 503 | | | 503 | | | 1,509 | | | 1,174 | | | 2028 Convertible Notes | | 860 | | | — | | | 860 | | | — | | | Total coupon interest | | $ | 1,524 | | | $ | 787 | | | $ | 3,098 | | | $ | 2,795 | | | | | | | | | | | | Amortization of debt discount: | | | | | | | | | | 2024 Convertible Notes | | $ | 84 | | | $ | 126 | | | $ | 338 | | | $ | 712 | | | 2027 Convertible Notes | | 847 | | | 842 | | | 2,537 | | | 1,962 | | | 2028 Convertible Notes | | 363 | | | — | | | 363 | | | — | | | Total amortization of debt discount | | $ | 1,294 | | | $ | 968 | | | $ | 3,238 | | | $ | 2,674 | | | | | | | | | | | | Interest expense: | | | | | | | | | | 2024 Convertible Notes | | $ | 245 | | | $ | 410 | | | $ | 1,067 | | | $ | 2,333 | | | 2027 Convertible Notes | | 1,350 | | | 1,345 | | | 4,046 | | | 3,136 | | | 2028 Convertible Notes | | 1,223 | | | — | | | 1,223 | | | — | | | Total interest expense | | $ | 2,818 | | | $ | 1,755 | | | $ | 6,336 | | | $ | 5,469 | | | | | | | | | | | | Effective interest rates: | | | | | | | | | | 2024 Convertible Notes | | 1.8 | % | | 1.8 | % | | 1.8 | % | | 1.8 | % | | 2027 Convertible Notes | | 0.7 | % | | 0.7 | % | | 0.7 | % | | 0.7 | % | | 2028 Convertible Notes | | 1.5 | % | | N/A | | 1.5 | % | | N/A |
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