Including the current and noncurrent portions, carrying amount of debt identified as being convertible into another form of financial instrument (typically the entity's common stock) as of the balance sheet date, which originally required full repayment more than twelve months after issuance or greater than the normal operating cycle of the company.

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The portion of the carrying value of long-term convertible debt as of the balance sheet date that is scheduled to be repaid within one year or in the normal operating cycle if longer. Convertible debt is a financial instrument which can be exchanged for a specified amount of another security, typically the entity's common stock, at the option of the issuer or the holder.

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Carrying amount of long-term convertible debt as of the balance sheet date, net of the amount due in the next twelve months or greater than the normal operating cycle, if longer. The debt is convertible into another form of financial instrument, typically the entity's common stock.

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Contractual interest rate for funds borrowed, under the debt agreement.

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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 requirements, and other securities issued that are redeemable by holder at fixed or determinable prices and dates maturing in the second fiscal year 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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Convertible Notes - Components and Maturities (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Convertible Notes
Less current portion		$ 7,393
Convertible senior notes noncurrent	$ 17,434	16,608
Annual maturities of Convertible Notes
2020	19,094,000
Total debt	19,094,000
Carrying Amount
Convertible Notes
Convertible senior notes	17,434	24,001
Less current portion		7,393
Convertible senior notes noncurrent	$ 17,434	$ 16,608
Convertible Senior Notes 0.375 Percent Due 2018
Convertible Notes
Interest rate of debt (as a percent)	0.375%	0.375%	0.375%
Convertible senior notes		$ 7,400
Convertible Senior Notes 0.375 Percent Due 2018 \| Carrying Amount
Convertible Notes
Convertible senior notes		$ 7,393
Convertible Senior Notes 1.25 Percent Due 2020
Convertible Notes
Interest rate of debt (as a percent)	1.25%	1.25%	1.25%
Convertible senior notes	$ 17,400	$ 16,600
Convertible Senior Notes 1.25 Percent Due 2020 \| Carrying Amount
Convertible Notes
Convertible senior notes	$ 17,434	$ 16,608