Notes Payable - 2.25% Convertible Senior Notes Due 2022 - Future Minimum Payments (Details) - USD ($) $ in Thousands	Jun. 30, 2020	Dec. 31, 2019
Future minimum payments of Convertible senior notes
2020	$ 3,608
2021	7,216
2022	126,556
2023	4,500
2024	203,750
2025	3,000
2026 and Thereafter	201,500
Total future minimum payments under the convertible senior notes	550,130
Less: amounts representing interest	(29,431)
Less: unamortized debt discount	(94,475)
Less: unamortized debt issuance costs	(7,300)
Net carrying amount	418,924
Convertible Senior Notes
Future minimum payments of Convertible senior notes
Less: unamortized debt discount	(94,475)	$ (104,700)
Less: unamortized debt issuance costs	(7,300)	(8,005)
Net carrying amount	$ 418,924	$ 407,994

Represents the amount of interest to be paid on long-term debt.

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Amount of long-term debt payable, sinking fund requirements, and other securities issued that are redeemable by holder at fixed or determinable prices and dates maturing in the Year Six and Thereafter following the latest fiscal year. Excludes interim and annual periods when interim periods are reported on a rolling approach, from latest balance sheet date.

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Amount, before unamortized (discount) premium and debt issuance costs, of long-term debt. Includes, but is not limited to, notes payable, bonds payable, commercial loans, mortgage loans, convertible debt, subordinated debt and other types of debt.

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Amount, after accumulated amortization, of debt discount.

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Amount, after unamortized (discount) premium and debt issuance costs, of long-term debt. Includes, but not limited to, notes payable, bonds payable, debentures, mortgage loans and commercial paper. Excludes capital lease obligations.

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Amount of long-term debt payable, sinking fund requirement, and other securities issued that are redeemable by holder at fixed or determinable price and date, maturing in next fiscal year following current fiscal year. Excludes interim and annual periods when interim periods are reported from current statement of financial position date (rolling approach).

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Amount of long-term debt payable, sinking fund requirement, and other securities issued that are redeemable by holder at fixed or determinable price and date, maturing in fifth fiscal year following current fiscal year. Excludes interim and annual periods when interim periods are reported from current statement of financial position date (rolling approach).

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Amount of long-term debt payable, sinking fund requirement, and other securities issued that are redeemable by holder at fixed or determinable price and date, maturing in remainder of current fiscal year.

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The remaining balance of debt issuance expenses that were capitalized and are being amortized against income over the lives of the respective bond issues. This does not include the amounts capitalized as part of the cost of the utility plant or asset.

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