Convertible Notes (Details) - USD ($) $ in Thousands	Mar. 31, 2016	Dec. 31, 2015
Debt Instrument [Line Items]
Other assets	$ 4,622	$ 2,165
Convertible notes, long-term	121,069	119,418
1.125% Convertible Senior Notes due 2018
Debt Instrument [Line Items]
Principal amount of convertible notes	138,000
Convertible Senior Notes
Debt Instrument [Line Items]
Total convertible notes	121,069	119,418
Convertible notes, short-term	0	0
Convertible notes, long-term	$ 121,069	$ 119,418
Convertible Senior Notes \| 1.125% Convertible Senior Notes due 2018
Debt Instrument [Line Items]
Convertible notes stated interest rate (as a percent)	1.125%	1.125%
Principal amount of convertible notes	$ 138,000	$ 138,000
Unamortized discount	(15,589)	(17,099)
Unamortized Debt Issuance Expense	(1,342)	(1,483)
Total convertible notes	$ 121,069	119,418
Adjustments for New Accounting Pronouncement [Member]
Debt Instrument [Line Items]
Other assets		2,165
Convertible notes, long-term		119,418
Scenario, Previously Reported [Member] \| Adjustments for New Accounting Pronouncement [Member]
Debt Instrument [Line Items]
Other assets		3,648
Convertible notes, long-term		120,901
Scenario, Adjustment [Member] \| Adjustments for New Accounting Pronouncement [Member]
Debt Instrument [Line Items]
Other assets		(1,483)
Convertible notes, long-term		$ (1,483)

Carrying value as of the balance sheet date of long-term debt (with maturities initially due after one year or beyond the operating cycle if longer) identified as Convertible Notes Payable, excluding current portion. Convertible Notes Payable is a written promise to pay a note which can be exchanged for a specified amount of another, related security, at the option of the issuer and the holder.

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-Publisher FASB
-Name Accounting Standards Codification
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-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.22)
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Including the current and noncurrent portions, carrying value as of the balance sheet date of a written promise to pay a note, initially due after one year or beyond the operating cycle if longer, which can be exchanged for a specified amount of one or more securities (typically common stock), at the option of the issuer or the holder.

+ References

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Carrying value as of the balance sheet date of the portion of long-term debt due within one year or the operating cycle if longer identified as Convertible Notes Payable. Convertible Notes Payable is a written promise to pay a note which can be exchanged for a specified amount of another, related security, at the option of the issuer and the holder.

+ References

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

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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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The amount of debt discount that was originally recognized at the issuance of the instrument that has yet to be amortized.

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Aggregate carrying amount, as of the balance sheet date, of noncurrent assets not separately disclosed in the balance sheet. Noncurrent assets are expected to be realized or consumed after one year (or the normal operating cycle, if longer).

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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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