Convertible Notes Convertible Notes (Interest Expense for February 2018 Notes) (Detail) (Details) (February 2018 Notes [Member], USD $) In Thousands, unless otherwise specified	3 Months Ended
Mar. 31, 2015	Mar. 31, 2014
February 2018 Notes [Member]
Debt Instrument [Line Items]
Contractual coupon interest	$ 3,000	$ 1,571
Amortization of debt issuance costs	543	222
Amortization of debt discount	1,747	671
Total	$ 5,290	$ 2,464

Amortization of debt issuance costs

No definition available.

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- Definition

Amount of noncash expense included in interest expense to amortize debt discount and premium associated with the related debt instruments. Excludes amortization of financing costs. Alternate captions include noncash interest expense.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 835

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-Name Accounting Standards Codification

-Topic 230

-SubTopic 10

-Section 45

-Paragraph 28

-Subparagraph (b)

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-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 03

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- Definition

Amount of the cost of borrowed funds accounted for as interest expense for debt.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 225

-SubTopic 10

-Section S99

-Paragraph 2

-Subparagraph (SX 210.5-03.8)

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-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

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- Definition

Represents the portion of interest incurred in the period on debt arrangements that was charged against earnings, excluding amortization of debt discount (premium) and financing costs.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 03

-Paragraph 8

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