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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-Publisher FASB
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- Definition

The carrying amount of the equity component of convertible debt which may be settled in cash upon conversion.

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- Definition

The amount by which the convertible debt's if-converted value exceeds its principle amount at the balance sheet date, regardless of whether the instrument is currently convertible. This element applies to public companies only.

+ References

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- Definition

Face (par) amount of debt instrument at time of issuance.

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- Definition

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

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Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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No definition available.

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Amount, after accumulated amortization, of debt discount.

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Convertible Senior Notes Components of consolidated balance sheets associated with convertible senior notes (Details) - USD ($)	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017	Dec. 31, 2017	Nov. 30, 2005	May 31, 2005
Debt Instrument [Line Items]
Convertible Debt	$ 61,650,000		$ 61,393,000
Carrying amount of equity component included in additional paid-in capital	108,714,000		108,714,000
Excess of instruments’ if-converted values over face principal amounts	0	$ 0
5.875% Convertible Senior Notes Due 2035 [Member]
Debt Instrument [Line Items]
Debt Instrument, Face Amount	88,280,000		88,280,000	$ 300,000,000.0
Debt Instrument, Unamortized Discount	$ 26,630,000		$ 26,887,000
Interest rate on notes				5.875%	5.875%