v2.4.0.8

Summary of Significant Accounting Policies - Additional Information (Detail) (USD $) In Thousands, unless otherwise specified | 3 Months Ended | 9 Months Ended | 12 Months Ended
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Sep. 30, 2013 Collaborator | Sep. 30, 2012 | Sep. 30, 2013 Segment Collaborator | Sep. 30, 2012 | Dec. 31, 2012 Segment | Dec. 31, 2011
Organization And Significant Accounting Policies [Line Items] |  |  |  |  |  |
Research and development commitments with third parties | $ 2,786 |  | $ 2,786 |  | $ 3,164 | $ 6,220
Research and development commitments with third parties not incurred | 1,267 |  | 1,267 |  | 1,431 | 1,665
Maturity period of liquid investment |  |  | 3 months |  | 3 months |
Cash equivalent investments in highly liquid money market accounts | 56,693 |  | 56,693 |  | 9,384 | 18,833
Short-term investments | 136,672 |  | 136,672 |  | 260 | 258
Fair value of financial assets measured at fair value on a recurring basis | 325,348 |  | 325,348 |  | 83,376 | 39,097
Unrealized appreciation (depreciation) in the fair value of the Company's equity securities | 27,339 | (3,940) | 5,704 | 12,031 | (6,290) | (2,675)
Carrying value of investment in VIEs | 11,540 |  | 11,540 |  | 5,726 |
Percentage of recognized income tax positions |  |  | 50.00% |  | 50.00% |
Number of segment |  |  | 1 |  | 1 |
Investments gross unrealized losses | 9 |  | 9 |  |  |
Number of collaborators identified as VIEs | 2 |  | 2 |  |  |
Equity Securities [Member] |  |  |  |  |  |
Organization And Significant Accounting Policies [Line Items] |  |  |  |  |  |
Fair value of financial assets measured at fair value on a recurring basis | 107,567 |  | 107,567 |  | 83,116 | 39,097
Ziopharm [Member] |  |  |  |  |  |
Organization And Significant Accounting Policies [Line Items] |  |  |  |  |  |
Company's ownership percentage of Ziopharm | 16.20% |  | 16.20% |  | 16.30% | 11.50%
Ziopharm [Member] | Equity Securities [Member] |  |  |  |  |  |
Organization And Significant Accounting Policies [Line Items] |  |  |  |  |  |
Fair value of financial assets measured at fair value on a recurring basis | 53,321 |  | 53,321 |  | 56,298 | 35,162
Unrealized appreciation (depreciation) in the fair value of the Company's equity securities | 24,766 | (4,948) | (2,977) | 8,773 | (7,194) | (4,924)
Certificates of Deposit [Member] |  |  |  |  |  |
Organization And Significant Accounting Policies [Line Items] |  |  |  |  |  |
Short-term investments |  |  |  |  | $ 260 | $ 258
Minimum [Member] |  |  |  |  |  |
Organization And Significant Accounting Policies [Line Items] |  |  |  |  |  |
Maturity of certificate of deposits |  |  |  |  | 3 Months |
Minimum [Member] | Patents and Related Technologies [Member] |  |  |  |  |  |
Organization And Significant Accounting Policies [Line Items] |  |  |  |  |  |
Period of estimated useful lives |  |  | 7 years |  | 7 years |
Minimum [Member] | Leasehold improvements [Member] |  |  |  |  |  |
Organization And Significant Accounting Policies [Line Items] |  |  |  |  |  |
Life of the asset |  |  | 1 year |  | 1 year |
Maximum [Member] |  |  |  |  |  |
Organization And Significant Accounting Policies [Line Items] |  |  |  |  |  |
Maturity of certificate of deposits |  |  |  |  | 1 Year |
Maximum [Member] | Patents and Related Technologies [Member] |  |  |  |  |  |
Organization And Significant Accounting Policies [Line Items] |  |  |  |  |  |
Period of estimated useful lives |  |  | 14 years |  | 14 years |
Maximum [Member] | Leasehold improvements [Member] |  |  |  |  |  |
Organization And Significant Accounting Policies [Line Items] |  |  |  |  |  |
Life of the asset |  |  | 4 years |  | 4 years |

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- Definition Fair value portion of probable future economic benefits obtained or controlled by an entity as a result of past transactions or events. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 820 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=25499696&loc=d3e19207-110258 + Details
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- Definition Investment in short-term money-market instruments (such as commercial paper, banker's acceptances, repurchase agreements, government securities, certificates of deposit, and so forth) which are highly liquid (that is, readily convertible to known amounts of cash) and so near their maturity that they present an insignificant risk of changes in value because of changes in interest rates. Generally, only investments with original maturities of three months or less qualify as cash equivalents by definition. Original maturity means an original maturity to the entity holding the investment. For example, both a three-month US Treasury bill and a three-year Treasury note purchased three months from maturity qualify as cash equivalents. However, a Treasury note purchased three-years ago does not become a cash equivalent when its remaining maturity is three months. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Glossary Cash Equivalents -URI http://asc.fasb.org/extlink&oid=6507016 + Details
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- Definition Number of operating segments. An operating segment is a component of an enterprise: (a) that engages in business activities from which it may earn revenues and incur expenses (including revenues and expenses relating to transactions with other components of the same enterprise), (b) whose operating results are regularly reviewed by the enterprise's chief operating decision maker to make decisions about resources to be allocated to the segment and assess its performance, and (c) for which discrete financial information is available. An operating segment may engage in business activities for which it has yet to earn revenues, for example, start-up operations may be operating segments before earning revenues. + References No definition available. + Details
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- Definition Investments which are intended to be sold in the short term (usually less than one year or the normal operating cycle, whichever is longer) including trading securities, available-for-sale securities, held-to-maturity securities, and other short-term investments not otherwise listed in the existing taxonomy. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02.2) -URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 03 -Paragraph 1 -Subparagraph g -Article 7 + Details
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- Definition Amount of accumulated pre-tax unrealized loss before deducting pre-tax unrealized gain on investments in available-for-sale debt securities impacting investments. + References No definition available. + Details
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- Definition Number of collaborators identified as vie. + References No definition available. + Details
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- Definition Research and development commitments. + References No definition available. + Details
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- Definition The carrying value of the entity's investment in identified Variable Interest Entities (VIEs). + References No definition available. + Details
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