v2.4.0.8

Summary of Significant Accounting Policies - Summarized Unaudited Financial Information (Detail) (USD $) In Thousands, unless otherwise specified | 3 Months Ended | 9 Months Ended | 12 Months Ended
--- | --- | --- | ---
Sep. 30, 2013 | Sep. 30, 2012 | Sep. 30, 2013 | Sep. 30, 2012 | Dec. 31, 2012 | Dec. 31, 2011
Schedule of Equity Method Investments [Line Items] |  |  |  |  |  |
Revenues | $ 6,133 | $ 2,925 | $ 16,890 | $ 7,269 | $ 13,925 | $ 8,171
Operating expenses | 18,170 | 19,410 | 57,187 | 70,123 | 89,082 | 90,598
Loss from operations | (12,037) | (16,485) | (40,297) | (62,854) | (75,157) | (82,427)
Net income (loss) | 14,991 | (20,490) | (27,890) | (50,937) | (81,874) | (85,280)
Ziopharm [Member] |  |  |  |  |  |
Schedule of Equity Method Investments [Line Items] |  |  |  |  |  |
Revenues | 200 | 200 | 600 | 600 |  |
Operating expenses | 9,315 | 21,927 | 51,592 | 63,926 |  |
Loss from operations | (9,115) | (21,727) | (50,992) | (63,326) |  |
Other | (7,598) | 3,903 | 2,789 | (2,581) |  |
Net income (loss) | $ (16,713) | $ (17,824) | $ (48,203) | $ (65,907) |  |

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