Basis of Presentation (Policies)	6 Months Ended
Jun. 30, 2011
Basis of Presentation and Revenue from Collaboration Agreement [Abstract]
Use of Estimates and Assumptions	*Use of Estimates and Assumptions* The preparation of financial statements in conformity with U.S. GAAP requires management to make estimates and assumptions that affect the amounts reported in the financial statements and accompanying notes. Thus, actual results could differ from those estimates. In the opinion of management, all adjustments consisting of normal recurring accruals considered necessary for a fair presentation have been included. Operating results for the three and six months ended June 30, 2011 are not necessarily indicative of the results that may be expected for the year ending December 31, 2011 or for any other future operating periods.
Principles of Consolidation	*Principles of Consolidation* The unaudited Condensed Consolidated Financial Statements include the accounts of the Company and its wholly owned subsidiaries. All significant intercompany balances and transactions have been eliminated in consolidation.
Segment Reporting	*Segment Reporting* The Company operates in one segment — the discovery and development of novel cancer therapies.
Recent Accounting Pronouncements	*Recent Accounting Pronouncements* In June 2011, the Financial Accounting Standards Board (“FASB”) issued Accounting Standards Update (“ASU”) ASU No. 2011-05, “Presentation of Comprehensive Income” which was issued to enhance comparability between entities that report under U.S. GAAP and IFRS, and to provide a more consistent method of presenting non-owner transactions that affect an entity’s equity. ASU 2011-05 eliminates the option to report other comprehensive income and its components in the statement of changes in stockholders’ equity and requires an entity to present the total of comprehensive income, the components of net income and the components of other comprehensive income either in a single continuous statement or in two separate but consecutive statements. This pronouncement is effective for fiscal years, and interim periods within those years, beginning after December 15, 2011. Early adoption of the new guidance is permitted and full retrospective application is required. The Company does not expect that the adoption of this accounting standard update will have any material impact on its results of operations or financial position. In May 2011, the FASB issued ASU No. 2011-04, “Amendments to Achieve Common Fair Value Measurement and Disclosure Requirements in U.S. GAAP and International Financial Reporting Standards (“IFRS”).” This pronouncement was issued to provide a consistent definition of fair value and ensure that the fair value measurement and disclosure requirements are similar between U.S. GAAP and IFRS. ASU 2011-04 changes certain fair value measurement principles and enhances the disclosure requirements particularly for Level 3 fair value measurements. This pronouncement is effective for reporting periods beginning on or after December 15, 2011, with early adoption prohibited. The new guidance will require prospective application. The Company is currently evaluating the impact, if any, that the adoption of this pronouncement may have on its results of operations or financial position.
Presentation of Comprehensive Income	In June 2011, the Financial Accounting Standards Board (“FASB”) issued Accounting Standards Update (“ASU”) ASU No. 2011-05, “Presentation of Comprehensive Income” which was issued to enhance comparability between entities that report under U.S. GAAP and IFRS, and to provide a more consistent method of presenting non-owner transactions that affect an entity’s equity. ASU 2011-05 eliminates the option to report other comprehensive income and its components in the statement of changes in stockholders’ equity and requires an entity to present the total of comprehensive income, the components of net income and the components of other comprehensive income either in a single continuous statement or in two separate but consecutive statements. This pronouncement is effective for fiscal years, and interim periods within those years, beginning after December 15, 2011. Early adoption of the new guidance is permitted and full retrospective application is required. The Company does not expect that the adoption of this accounting standard update will have any material impact on its results of operations or financial position.
Fair Value Measurements and Disclosures	In May 2011, the FASB issued ASU No. 2011-04, “Amendments to Achieve Common Fair Value Measurement and Disclosure Requirements in U.S. GAAP and International Financial Reporting Standards (“IFRS”).” This pronouncement was issued to provide a consistent definition of fair value and ensure that the fair value measurement and disclosure requirements are similar between U.S. GAAP and IFRS. ASU 2011-04 changes certain fair value measurement principles and enhances the disclosure requirements particularly for Level 3 fair value measurements. This pronouncement is effective for reporting periods beginning on or after December 15, 2011, with early adoption prohibited. The new guidance will require prospective application. The Company is currently evaluating the impact, if any, that the adoption of this pronouncement may have on its results of operations or financial position.
Revenue Recognition	Ono also agreed to pay the Company global development support and commercial milestone payments based on the achievement of pre-specified criteria, which could total approximately $289.3 million at current exchange rates. In April 2010, the FASB issued ASU No. 2010-17, Milestone Method of Revenue Recognition, which states that entities can apply the milestone method of revenue recognition to research or development arrangements if the milestones under the arrangements are substantive and there is substantive uncertainty about whether the milestones will be achieved. The Company adopted ASU No. 2010-17 effective January 2010 and determined that the milestones under the agreement with Ono will not be accounted for under the milestone method of revenue recognition. The milestones under the agreement with Ono do not meet the definition of a milestone under ASU 2010-17 because the achievement of these milestones is solely dependent on Ono’s performance and not on any performance obligations of the Company. Revenue from the milestone payments will be recognized if and when such payments become due because the Company does not expect to have any outstanding performance obligations relating to these milestones at the time these milestones are achieved.
Investments-Other	In connection with the termination of the collaboration agreement with SBIO, during the first quarter of 2011, the Company concluded that it will no longer receive clinical development services subsequent to March 31, 2011 relating to the $20.0 million advance funding payment provided to SBIO in May 2010. The Company recorded a $12.7 million write-off during the first quarter of 2011, for the remaining unamortized balance of prepaid research and development expense relating to the advance funding payment. In addition, the Company reassessed the fair value of its equity investment in SBIO in accordance with Accounting Standards Codification (“ASC”) 325-20-35, Investments—Other*, and determined that it was impaired, accordingly, in the first quarter of 2011, the Company recorded an impairment charge of $3.0 million in the “Other expense” line item in the Condensed Consolidated Statement of Operations.
Other Expenses	The Company’s foreign currency options used to hedge anticipated cash flows, where the underlying exposures are the net of Euro-denominated revenues and expenses, are not designated as hedging instruments under ASC 815. The changes in the fair value of these foreign currency options are included in the “Other expense” line item in the Condensed Consolidated Statements of Operations.
Derivatives	The Company is exposed to counterparty credit risk on all of its derivative financial instruments. The Company has established and maintained strict counterparty credit guidelines and enters into derivative instruments only with financial institutions that are investment grade to minimize the Company’s exposure to potential defaults. The Company does not generally require collateral to be pledged under these agreements.
Financial Instruments	*Convertible Senior Notes due 2016* Level 2 liabilities consist of the Company’s convertible senior notes due 2016. The fair value of these convertible senior notes is estimated by computing the fair value of a similar liability without the conversion option. Refer to Note 10 for further details on the fair value. In accordance with ASC 825-10, Financial Instruments, the estimated market value of the Company’s convertible senior notes as of June 30, 2011 was $271.4 million. The Company’s convertible senior notes are not marked-to-market and are shown at their original issuance value net of the amortized discount and the portion of the value allocated to the conversion option is included in stockholders’ equity in the accompanying unaudited Condensed Consolidated Balance Sheet June 30, 2011.
Convertible Debt	The 2016 Notes are accounted for in accordance with ASC 470-20. Under ASC 470-20 issuers of certain convertible debt instruments that have a net settlement feature and may be settled in cash upon conversion, including partial cash settlement, are required to separately account for the liability (debt) and equity (conversion option) components of the instrument. The carrying amount of the liability component of any outstanding debt instrument is computed by estimating the fair value of a similar liability without the conversion option. The amount of the equity component is then calculated by deducting the fair value of the liability component from the principal amount of the convertible debt instrument.
Income Taxes	The Company calculates its quarterly income tax provision in accordance with ASC 740-270, Income Taxes. Under this method, deferred tax assets and liabilities are determined based on differences between the financial reporting and tax bases of assets and liabilities and are measured using the enacted tax rates and laws that will be in effect when the differences are expected to reverse. The Company has established and continues to maintain a valuation allowance against the majority of its deferred tax assets as the Company does not currently believe that realization of those assets is more likely than not.

Basis of Presentation (Policies)

6 Months Ended

Jun. 30, 2011

Basis of Presentation and Revenue from Collaboration Agreement [Abstract]

Use of Estimates and Assumptions

The preparation of financial statements in conformity with U.S. GAAP requires management to make estimates and assumptions that affect the amounts reported in the financial statements and accompanying notes. Thus, actual results could differ from those estimates. In the opinion of management, all adjustments consisting of normal recurring accruals considered necessary for a fair presentation have been included. Operating results for the three and six months ended June 30, 2011 are not necessarily indicative of the results that may be expected for the year ending December 31, 2011 or for any other future operating periods.

Principles of Consolidation

Principles of Consolidation

The unaudited Condensed Consolidated Financial Statements include the accounts of the Company and its wholly owned subsidiaries. All significant intercompany balances and transactions have been eliminated in consolidation.

Segment Reporting

Segment Reporting

The Company operates in one segment — the discovery and development of novel cancer therapies.

Recent Accounting Pronouncements

Recent Accounting Pronouncements

In June 2011, the Financial Accounting Standards Board (“FASB”) issued Accounting Standards Update (“ASU”) ASU No. 2011-05, “Presentation of Comprehensive Income” which was issued to enhance comparability between entities that report under U.S. GAAP and IFRS, and to provide a more consistent method of presenting non-owner transactions that affect an entity’s equity. ASU 2011-05 eliminates the option to report other comprehensive income and its components in the statement of changes in stockholders’ equity and requires an entity to present the total of comprehensive income, the components of net income and the components of other comprehensive income either in a single continuous statement or in two separate but consecutive statements. This pronouncement is effective for fiscal years, and interim periods within those years, beginning after December 15, 2011. Early adoption of the new guidance is permitted and full retrospective application is required. The Company does not expect that the adoption of this accounting standard update will have any material impact on its results of operations or financial position.

In May 2011, the FASB issued ASU No. 2011-04, “Amendments to Achieve Common Fair Value Measurement and Disclosure Requirements in U.S. GAAP and International Financial Reporting Standards (“IFRS”).” This pronouncement was issued to provide a consistent definition of fair value and ensure that the fair value measurement and disclosure requirements are similar between U.S. GAAP and IFRS. ASU 2011-04 changes certain fair value measurement principles and enhances the disclosure requirements particularly for Level 3 fair value measurements. This pronouncement is effective for reporting periods beginning on or after December 15, 2011, with early adoption prohibited. The new guidance will require prospective application. The Company is currently evaluating the impact, if any, that the adoption of this pronouncement may have on its results of operations or financial position.

Presentation of Comprehensive Income

Fair Value Measurements and Disclosures

Revenue Recognition

Ono also agreed to pay the Company global development support and commercial milestone payments based on the achievement of pre-specified criteria, which could total approximately $289.3 million at current exchange rates. In April 2010, the FASB issued ASU No. 2010-17, Milestone Method of Revenue Recognition, which states that entities can apply the milestone method of revenue recognition to research or development arrangements if the milestones under the arrangements are substantive and there is substantive uncertainty about whether the milestones will be achieved. The Company adopted ASU No. 2010-17 effective January 2010 and determined that the milestones under the agreement with Ono will not be accounted for under the milestone method of revenue recognition. The milestones under the agreement with Ono do not meet the definition of a milestone under ASU 2010-17 because the achievement of these milestones is solely dependent on Ono’s performance and not on any performance obligations of the Company. Revenue from the milestone payments will be recognized if and when such payments become due because the Company does not expect to have any outstanding performance obligations relating to these milestones at the time these milestones are achieved.

Investments-Other

In connection with the termination of the collaboration agreement with S*BIO, during the first quarter of 2011, the Company concluded that it will no longer receive clinical development services subsequent to March 31, 2011 relating to the $20.0 million advance funding payment provided to S*BIO in May 2010. The Company recorded a $12.7 million write-off during the first quarter of 2011, for the remaining unamortized balance of prepaid research and development expense relating to the advance funding payment. In addition, the Company reassessed the fair value of its equity investment in S*BIO in accordance with Accounting Standards Codification (“ASC”) 325-20-35, Investments—Other, and determined that it was impaired, accordingly, in the first quarter of 2011, the Company recorded an impairment charge of $3.0 million in the “Other expense” line item in the Condensed Consolidated Statement of Operations.

Other Expenses

The Company’s foreign currency options used to hedge anticipated cash flows, where the underlying exposures are the net of Euro-denominated revenues and expenses, are not designated as hedging instruments under ASC 815. The changes in the fair value of these foreign currency options are included in the “Other expense” line item in the Condensed Consolidated Statements of Operations.

Derivatives

The Company is exposed to counterparty credit risk on all of its derivative financial instruments. The Company has established and maintained strict counterparty credit guidelines and enters into derivative instruments only with financial institutions that are investment grade to minimize the Company’s exposure to potential defaults. The Company does not generally require collateral to be pledged under these agreements.

Financial Instruments

Convertible Senior Notes due 2016

Level 2 liabilities consist of the Company’s convertible senior notes due 2016. The fair value of these convertible senior notes is estimated by computing the fair value of a similar liability without the conversion option. Refer to Note 10 for further details on the fair value. In accordance with ASC 825-10, Financial Instruments, the estimated market value of the Company’s convertible senior notes as of June 30, 2011 was $271.4 million. The Company’s convertible senior notes are not marked-to-market and are shown at their original issuance value net of the amortized discount and the portion of the value allocated to the conversion option is included in stockholders’ equity in the accompanying unaudited Condensed Consolidated Balance Sheet June 30, 2011.

Convertible Debt

The 2016 Notes are accounted for in accordance with ASC 470-20. Under ASC 470-20 issuers of certain convertible debt instruments that have a net settlement feature and may be settled in cash upon conversion, including partial cash settlement, are required to separately account for the liability (debt) and equity (conversion option) components of the instrument. The carrying amount of the liability component of any outstanding debt instrument is computed by estimating the fair value of a similar liability without the conversion option. The amount of the equity component is then calculated by deducting the fair value of the liability component from the principal amount of the convertible debt instrument.

Income Taxes

The Company calculates its quarterly income tax provision in accordance with ASC 740-270, Income Taxes. Under this method, deferred tax assets and liabilities are determined based on differences between the financial reporting and tax bases of assets and liabilities and are measured using the enacted tax rates and laws that will be in effect when the differences are expected to reverse. The Company has established and continues to maintain a valuation allowance against the majority of its deferred tax assets as the Company does not currently believe that realization of those assets is more likely than not.