Commitments and Contingencies - Additional Information (Detail)										1 Months Ended	3 Months Ended		6 Months Ended		12 Months Ended
	Jun. 29, 2016 $ / shares shares	Sep. 28, 2015 USD ($)	May 22, 2015 USD ($)	Mar. 31, 2015 USD ($)	Jan. 13, 2015 USD ($) shares	Jan. 09, 2015 USD ($) shares	Mar. 07, 2011 USD ($)	Jan. 06, 2011	Aug. 24, 2004 Patent	Jul. 31, 2015 USD ($)	Jun. 30, 2016 USD ($) $ / shares	Jun. 30, 2015 USD ($)	Jun. 30, 2016 USD ($) $ / shares shares	Jun. 30, 2015 USD ($)	Dec. 31, 2015 USD ($) $ / shares shares	Dec. 31, 2013 USD ($)	Dec. 31, 2012	Dec. 31, 2011 USD ($)	Mar. 31, 2016 USD ($)	May 31, 2015 USD ($)	Dec. 31, 2014 USD ($) shares
Commitments and Contingencies Disclosure [Line Items]
Loss on disposal of fixed assets														$ 1,000
Total rent Expense													$ 122,000	477,000
Deferred rent - current portion											$ 223,000		223,000		$ 348,000
Deferred rent-non-current portion											200,000		200,000		313,000
Deferred rent liability net											423,000		423,000		$ 661,000
Research and Development Expense											$ 129,228,000	$ 7,424,000	$ 139,427,000	81,673,000
Preferred stock, stated value | $ / shares											$ 0.001		$ 0.001		$ 0.001
Research and development arrangement Terms					Pursuant to the Research and Development Agreement, the Company, Intrexon and MD Anderson have agreed to form a joint steering committee that will oversee and manage the new and ongoing research programs. As provided under the MD Anderson License, the Company will provide funding for research and development activities in support of the research programs under the Research and Development Agreement for a period of three years and in an amount of no less than $15 million and no greater than $20 million per year.
Research and Development Service Agreement Aggregate Quarterly Payments													$ 3,800,000
Offset costs in research and development expense													1,700,000
Research and Development Service Agreement Aggregate Payments													18,800,000
Deferred revenue - current portion											$ 6,389,000		6,389,000		$ 6,861,000
Deferred Revenue, long term											44,722,000		$ 44,722,000		47,917,000
Issuance of common stock in a license agreement														67,285,000
The University of Texas MD Anderson Cancer Center and The Texas A & M University System
Commitments and Contingencies Disclosure [Line Items]
Milestone maximum payment																					$ 4,500,000
Number of products | Patent									2
Options to purchase common stock | shares													50,222
Shares vested | shares																					37,666
The University of Texas MD Anderson Cancer Center and The Texas A & M University System | Research and Development Expense
Commitments and Contingencies Disclosure [Line Items]
Issuance of common stock in a license agreement													$ 87,000
The University of Texas MD Anderson Cancer Center and The Texas A & M University System | Upon enrollment of the first patient in a multi-center pivotal clinical trial
Commitments and Contingencies Disclosure [Line Items]
Shares vested | shares																					12,556
Solasia
Commitments and Contingencies Disclosure [Line Items]
Upfront payment received							$ 5,000,000
Milestone payment received																			$ 1,000,000
Milestone Payments Payable																			$ 1,000,000
Solasia | Development-based milestones
Commitments and Contingencies Disclosure [Line Items]
Expected Additional milestone payments to be received													32,500,000
Solasia | Sales-based milestones
Commitments and Contingencies Disclosure [Line Items]
Expected Additional milestone payments to be received													53,500,000
Baxter Healthcare Corporation | Upon the successful U.S. IND application for indibulin
Commitments and Contingencies Disclosure [Line Items]
Installment payments													0	$ 0
License Agreement
Commitments and Contingencies Disclosure [Line Items]
Research and Development Expense													$ 67,300,000		$ 67,300,000
Issuance of common stock in licensing agreement, shares | shares													11,722,163		11,722,163
ARES Trading License
Commitments and Contingencies Disclosure [Line Items]
Agreement termination, notice period													90 days
Payments for development and commercial milestones per Product													$ 413,000,000
Milestone payments, percentage													50.00%
Agreement commencement date													2015-05
Deferred revenue, revenue recognized											1,600,000		$ 3,200,000
Deferred revenue, upfront payment											51,100,000		51,100,000							$ 57,500,000
Deferred revenue - current portion											6,400,000		6,400,000
Minimum
Commitments and Contingencies Disclosure [Line Items]
Research and Development Expense					$ 15,000,000
Maximum
Commitments and Contingencies Disclosure [Line Items]
Research and Development Expense					20,000,000
Prepaid Expenses and Other Current Assets
Commitments and Contingencies Disclosure [Line Items]
Pre paid research and development expenses											17,100,000		$ 17,100,000
Intrexon Corporation
Commitments and Contingencies Disclosure [Line Items]
Contract termination description													The Company's obligation to pay 50% of net profits (now 20% of net profits after the amendment pursuant to the 2016 ECP Amendment, discussed below) or revenue described above with respect to these "retained" products will survive termination of the Channel Agreement.
Licensing fee		$ 10,000,000								$ 115,000,000
Milestone payment receivable													$ 5,000,000
Milestone payment receivable period													2 years
Upfront payment received										$ 57,500,000
Percentage of upfront fee Payable										50.00%
Milestone maximum payment											50,000,000		$ 50,000,000
Intrexon Corporation | 2016 GvHD Amendment
Commitments and Contingencies Disclosure [Line Items]
Royalty percentage of net profit													50.00%
Contract termination description													The Company's obligation to pay 50% of net profits or revenue with respect to these "retained" products will survive termination of the GvHD Agreement.
Licensing fee		$ 10,000,000
Research and Development Expense															$ 10,000,000
Agreement termination period		24 months
Agreement termination, notice period		90 days
Intrexon Corporation | License Agreement
Commitments and Contingencies Disclosure [Line Items]
Cash consideration for license agreement					$ 50,000,000
Intrexon Corporation | Letter Agreement
Commitments and Contingencies Disclosure [Line Items]
Cash consideration for license agreement						$ 7,500,000
Intrexon Corporation | Quarterly Payment
Commitments and Contingencies Disclosure [Line Items]
Royalty percentage of net profit								50.00%
Percentage of revenue agreed to pay which is obtained from sublicensor								50.00%
Intrexon Corporation | Quarterly Payment | 2016 GvHD Amendment | Before Amendment
Commitments and Contingencies Disclosure [Line Items]
Royalty percentage of net profit	50.00%
Intrexon Corporation | Quarterly Payment | 2016 GvHD Amendment | 2016 GvHD Amendment
Commitments and Contingencies Disclosure [Line Items]
Royalty percentage of net profit	20.00%
Intrexon Corporation | Quarterly Payment | ECP Channel Agreement | 2016 ECP Amendment
Commitments and Contingencies Disclosure [Line Items]
Royalty percentage of net profit	20.00%
Intrexon Corporation | Quarterly Payment | ECP Channel Agreement | Before Amendment
Commitments and Contingencies Disclosure [Line Items]
Royalty percentage of net profit	50.00%
Intrexon Corporation | Series 1 Preferred Stock
Commitments and Contingencies Disclosure [Line Items]
Stock reserved for future issuance | shares	100,000
Preferred stock, stated value | $ / shares	$ 1,200
ZIOPHARM | License Agreement
Commitments and Contingencies Disclosure [Line Items]
Common stock issued for cash | shares					10,124,561
Cash consideration for license agreement					$ 50,000,000
ZIOPHARM | Letter Agreement
Commitments and Contingencies Disclosure [Line Items]
Common stock issued for cash | shares						1,597,602
Cash consideration for license agreement						$ 7,500,000
Boston, MA
Commitments and Contingencies Disclosure [Line Items]
Operating lease expiration month and year			2016-08															2016-08
Loss on sublease																$ 42,000
Remaining contractual obligation																367,000
Sublease revenue from subtenant			$ 105,000													325,000
Security deposits			$ 17,000								128,000		$ 128,000		$ 128,000
Sublease term amendment													Aug. 31, 2021
Security deposit from subtenant																					$ 20,000
Boston, MA | The first floor
Commitments and Contingencies Disclosure [Line Items]
Loss on sublease				$ 167,000
New York, NY
Commitments and Contingencies Disclosure [Line Items]
Letter of credit											$ 388,000		$ 388,000					$ 388,000
Operating lease expiration month and year																	2018-10
Loss on sublease																729,000
Remaining contractual obligation																2,300,000
Sublease revenue from subtenant																1,600,000
Loss on disposal of fixed assets																$ (392,000)