Collaboration Agreement - Collaboration Agreements with Astellas - Additional Information (Detail) (USD $) In Millions, unless otherwise specified	3 Months Ended
Mar. 31, 2015	Dec. 31, 2009
Collaborative agreement [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Co-promotion of sales and medical affairs percentage	50.00%
Astellas Pharma Inc. [Member] \| Collaborative agreement [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Range of percentage rates for royalties received on ex-U.S. net sales, as defined by collaboration agreement	Low teens to the low twenties
Up-front cash payment arrangement [Member] \| Astellas Pharma Inc. [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Non-refundable, upfront cash payment		$ 110.0
Development milestone payments [Member] \| Astellas Pharma Inc. [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Eligible to receive milestone payments	335.0
Milestone payments earned	335.0
Sales milestone payments [Member] \| Astellas Pharma Inc. [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Eligible to receive milestone payments	320.0
Milestone payments earned	75.0
Remaining future milestone payments eligible to receive	245.0

Percentage of expenses for co-promotion of sales and medical affairs.

No definition available.

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- Definition

Maximum dollar amount of milestone payments eligible to be received under a collaboration arrangement.

+ References

No definition available.

+ Details

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- Definition

Dollar amount of milestone payments earned to date pursuant to collaboration agreement.

+ References

No definition available.

+ Details

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- Definition

Remaining sales milestone payments that are eligible to be received in the future under collaboration arrangements.

+ References

No definition available.

+ Details

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- Definition

Range of percentage rates for royalties received on ex-U.S. net sales, as defined by collaboration agreement.

+ References

No definition available.

+ Details

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- Definition

Amount of deferred revenue recognized for transactions arising during the current reporting period. Deferred revenue is a liability as of the balance sheet date related to a revenue producing activity for which revenue has not yet been recognized. Generally, an Entity records deferred revenue when it receives consideration from a customer before achieving certain criteria that must be met for revenue to be recognized in conformity with GAAP.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 605

-SubTopic 10

-Section S99

-Paragraph 1

-Subparagraph (SAB TOPIC 13.A.4(a).Q1)

-URI http://asc.fasb.org/extlink&oid=27012821&loc=d3e214044-122780

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

-Publisher SEC

-Name Staff Accounting Bulletin (SAB)

-Number Topic 13

-Section A

+ Details

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- Details

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- Details

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- Details

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- Details

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