Share-Based Compensation - Share-Based Compensation Expense (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
Dec. 31, 2014	Dec. 31, 2013
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based compensation expense included in operating expenses	$ 8,992	$ 12,373
Stock options	1,152us-gaap_StockOptionPlanExpense	7,762us-gaap_StockOptionPlanExpense
Restricted stock awards and restricted stock units	7,840us-gaap_RestrictedStockExpense	4,611us-gaap_RestrictedStockExpense
Share-based compensation expense included in operating expenses	8,992us-gaap_ShareBasedCompensation	12,373us-gaap_ShareBasedCompensation
Research and development [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based compensation expense included in operating expenses	1,265	992
General and administrative [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based compensation expense included in operating expenses	$ 7,727	$ 11,381

Represents the expense recognized during the period arising from equity-based compensation arrangements (for example, shares of stock, unit, stock options or other equity instruments) with employees, directors and certain consultants qualifying for treatment as employees.

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 718

-SubTopic 10

-Section 50

-Paragraph 1

-Subparagraph (b)

-URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5047-113901

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 718

-SubTopic 10

-Section S99

-Paragraph 1

-Subparagraph (SAB TOPIC 14.F)

-URI http://asc.fasb.org/extlink&oid=27013229&loc=d3e301413-122809

Reference 3: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

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-Section 50

-Paragraph 2

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-URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901

Reference 4: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Staff Accounting Bulletin (SAB)

-Number Topic 14

-Section F

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- Definition

The noncash expense that represents the cost of restricted stock or unit distributed to employees as compensation.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 230

-SubTopic 10

-Section 45

-Paragraph 28

-Subparagraph (b)

-URI http://asc.fasb.org/extlink&oid=31042434&loc=d3e3602-108585

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- Definition

The aggregate amount of noncash, equity-based employee remuneration. This may include the value of stock or unit options, amortization of restricted stock or units, and adjustment for officers' compensation. As noncash, this element is an add back when calculating net cash generated by operating activities using the indirect method.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 230

-SubTopic 10

-Section 45

-Paragraph 28

-Subparagraph (a)

-URI http://asc.fasb.org/extlink&oid=31042434&loc=d3e3602-108585

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- Definition

The noncash expense that accounts for the value of stock or unit options distributed to employees as compensation.

+ References

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