| **Revenue Recognition**            | 9 Months Ended                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                        |
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| **Revenue Recognition [Abstract]** |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  |
| Revenue Recognition                | 2.  Revenue RecognitionWe recognize revenue from all sources based on the provisions of the SEC's Staff Accounting Bulletin (SAB) No. 104 (SAB 104) and ASC 605 Revenue Recognition. Under ASC 605, the delivered items are separate units of accounting, provided (i) the delivered items have value to a collaborator on a stand-alone basis, and (ii) if the arrangement includes a general right of return relative to the delivered item, delivery or performance of the undelivered items is considered probable and substantially in our control. In April 2010, the FASB issued a separate update to ASC 605 which provides guidance on the criteria that should be met when determining whether the milestone method of revenue recognition is appropriate. This method is effective on a prospective basis for milestones achieved after January 1, 2011.There have been no changes to our revenue recognition accounting policies as of and for the nine months ended September 30, 2012 which policies are disclosed in Note 2 to the consolidated financial statements included in our Annual Report on Form 10-K for the year ended December 31, 2011.License Agreement with Salix – February 2011Under our License Agreement, Salix is responsible for further developing and commercializing Relistor worldwide other than Japan, including completing clinical development necessary to support regulatory marketing approvals for potential new indications and formulations. We have granted Salix an exclusive license of relevant know-how, patent rights and technology, assigned relevant third-party contracts and we are responsible for serving on joint committees provided for in the License Agreement. We expect to perform joint committee services through 2013. We recognized $0.2 million and $59.6 million during the nine months ended September 30, 2012 and 2011, respectively, and $59.6 million for the year ended December 31, 2011, all from the $60.0 million upfront payment. At September 30, 2012, the $0.2 million remaining deferred revenue, which pertains to joint committee services, will be recognized in collaboration revenue as such activities are performed in the future. |

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| - Definition
Disclosure of accounting policy for revenue recognition. If the entity has different policies for different types of revenue transactions, the policy for each material type of transaction is generally disclosed. If a sales transaction has multiple element arrangements (for example, delivery of multiple products, services or the rights to use assets) the disclosure may indicate the accounting policy for each unit of accounting as well as how units of accounting are determined and valued. The disclosure may encompass important judgment as to appropriateness of principles related to recognition of revenue. The disclosure also may indicate the entity's treatment of any unearned or deferred revenue that arises from the transaction.
+ 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.B.Q1) -URI http://asc.fasb.org/extlink&oid=6600647&loc=d3e214044-122780Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher AICPA -Name Accounting Principles Board Opinion (APB) -Number 22 -Paragraph 8, 12, 13 -LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009.  This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 235 -SubTopic 10 -Section 50 -Paragraph 3 -URI http://asc.fasb.org/extlink&oid=6367646&loc=d3e18780-107790Reference 4: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 235 -SubTopic 10 -Section 50 -Paragraph 4 -URI http://asc.fasb.org/extlink&oid=6367646&loc=d3e18823-107790Reference 5: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 235 -SubTopic 10 -Section 50 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=6367646&loc=d3e18726-107790Reference 6: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Staff Accounting Bulletin (SAB) -Number Topic 13 -Section B -Paragraph Question 1
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