Development Stage Supplemental Equity Disclosure - Summary of Company's Equity Transactions (Detail) (USD $) In Thousands, except Per Share data, unless otherwise specified	12 Months Ended
	Dec. 31, 2012
Equity [Line Items]
Price per Share or Exercise Price per Share	$ 5.19
Common Stock [Member]
Equity [Line Items]
Date of Issuance	January 30, 2009
Shares of Common Stock	58,398
CytRx Transaction One [Member] | Common Stock [Member]
Equity [Line Items]
Date of Issuance	January 8, 2007
Price per Share or Exercise Price per Share	$ 0.007
Shares of Common Stock	7,040,318
Dollar Amount of Consideration	$ 48
UMMS [Member] | Common Stock [Member]
Equity [Line Items]
Date of Issuance	April 30, 2007
Price per Share or Exercise Price per Share	$ 5.000
Shares of Common Stock	462,112
Dollar Amount of Consideration	2,311
CytRx Transaction Three [Member] | Common Stock [Member]
Equity [Line Items]
Date of Issuance	September 28, 2007
Price per Share or Exercise Price per Share	$ 5.190
Shares of Common Stock	188,387
Dollar Amount of Consideration	978
Restricted Stock Units Transaction Two [Member] | Common Stock [Member]
Equity [Line Items]
Date of Issuance	March 15, 2011
Price per Share or Exercise Price per Share	$ 1.160
Shares of Common Stock	220,729
Dollar Amount of Consideration	256
Acquired Company [Member] | Common Stock [Member]
Equity [Line Items]
Date of Issuance	April 13, 2011
Shares of Common Stock	4,974,090
Dollar Amount of Consideration	6,367
Exchange with Warrant Holders [Member] | Common Stock [Member]
Equity [Line Items]
Date of Issuance	December 6, 2011
Shares of Common Stock	4,151,000
Dollar Amount of Consideration	3,120
Stock Compensation [Member] | Common Stock [Member]
Equity [Line Items]
Date of Issuance	Various - 2011
Shares of Common Stock	599,051
Dollar Amount of Consideration	594
Contingent Purchase Price Consideration [Member] | Common Stock [Member]
Equity [Line Items]
Date of Issuance	June 15, 2012
Shares of Common Stock	1,315,849
Dollar Amount of Consideration	1,579
Stock Compensation One [Member] | Common Stock [Member]
Equity [Line Items]
Date of Issuance	Various - 2012
Shares of Common Stock	288,285
Dollar Amount of Consideration	364
Founders [Member] | Common Stock [Member]
Equity [Line Items]
Date of Issuance	April 3, 2006
Shares of common stock	1,624,278
Dollars Amount of Consideration	2
Price per Share or Exercise Price per Share	$ 0.002
CytRx Transaction Two [Member] | Common Stock [Member]
Equity [Line Items]
Date of Issuance	April 30, 2007
Shares of common stock	3,273,292
Dollars Amount of Consideration	15,348
Price per Share or Exercise Price per Share	$ 5.190
Directors [Member] | Common Stock [Member]
Equity [Line Items]
Date of Issuance	August 18, 2007
Shares of common stock	30,000
Dollars Amount of Consideration	150
Price per Share or Exercise Price per Share	$ 5.000
Exercise of Stock Options Transaction One [Member] | Common Stock [Member]
Equity [Line Items]
Date of Issuance	November 21, 2007
Shares of common stock	66,045
Dollars Amount of Consideration	331
Price per Share or Exercise Price per Share	$ 5.000
PIPE [Member] | Common Stock [Member]
Equity [Line Items]
Date of Issuance	June 26, 2008
Shares of common stock	1,073,299
Dollars Amount of Consideration	7,918
Price per Share or Exercise Price per Share	$ 8.120
Exercise of Stock Options Transaction Two [Member] | Common Stock [Member]
Equity [Line Items]
Date of Issuance	October 6, 2008 and November 16, 2008
Shares of common stock	5,500
Dollars Amount of Consideration	26
Price per Share or Exercise Price per Share	$ 5.000
Exercise of Stock Options Transaction Three [Member] | Common Stock [Member]
Equity [Line Items]
Date of Issuance	May 1, 2009
Shares of common stock	281
Price per Share or Exercise Price per Share	$ 4.190
Registered Direct Transaction One [Member] | Common Stock [Member]
Equity [Line Items]
Date of Issuance	August 3, 2009 and August 4, 2009
Shares of common stock	2,385,715
Dollars Amount of Consideration	7,714
Price per Share or Exercise Price per Share	$ 3.500
Registered Direct Transaction Two [Member] | Common Stock [Member]
Equity [Line Items]
Date of Issuance	March 22, 2010
Shares of common stock	2,700,000
Dollars Amount of Consideration	15,235
Price per Share or Exercise Price per Share	$ 6.000
Exercise of Stock Options Transaction Four [Member] | Common Stock [Member]
Equity [Line Items]
Date of Issuance	Various - 2010
Shares of common stock	53,500
Dollars Amount of Consideration	254
Price per Share or Exercise Price per Share	$ 4.750
Restricted Stock Units Transaction One [Member] | Common Stock [Member]
Equity [Line Items]
Date of Issuance	January 2, 2010 and February 9, 2010
Shares of common stock	86,634
Dollars Amount of Consideration	207
Registered Direct Transaction Three [Member] | Common Stock [Member]
Equity [Line Items]
Date of Issuance	March 4, 2011
Shares of common stock	6,000,000
Dollars Amount of Consideration	7,307
Price per Share or Exercise Price per Share	$ 1.350
Registered Direct Transaction Four [Member] | Common Stock [Member]
Equity [Line Items]
Date of Issuance	April 20, 2011
Shares of common stock	11,950,000
Dollars Amount of Consideration	10,853
Price per Share or Exercise Price per Share	$ 1.000
ESPP [Member] | Common Stock [Member]
Equity [Line Items]
Date of Issuance	July 1, 2011
Shares of common stock	18,824
Dollars Amount of Consideration	15
Price per Share or Exercise Price per Share	$ 0.830
Exercise of Warrants [Member] | Common Stock [Member]
Equity [Line Items]
Date of Issuance	July 27, 2011
Shares of common stock	150,000
Dollars Amount of Consideration	150
Price per Share or Exercise Price per Share	$ 1.000
Registered Direct Transaction Five [Member] | Common Stock [Member]
Equity [Line Items]
Date of Issuance	September 26, 2011
Shares of common stock	700,000
Dollars Amount of Consideration	455
Price per Share or Exercise Price per Share	$ 0.650
ESPP One [Member] | Common Stock [Member]
Equity [Line Items]
Date of Issuance	January 1, 2012
Shares of common stock	98,758
Dollars Amount of Consideration	39
Price per Share or Exercise Price per Share	$ 0.390
Registered Direct Transaction Six [Member] | Common Stock [Member]
Equity [Line Items]
Date of Issuance	February 17, 2012
Shares of common stock	579,710
Dollars Amount of Consideration	385
Price per Share or Exercise Price per Share	$ 0.690
Registered Direct Transaction Seven [Member] | Common Stock [Member]
Equity [Line Items]
Date of Issuance	April 13, 2012
Shares of common stock	9,751,000
Dollars Amount of Consideration	13,478
Price per Share or Exercise Price per Share	$ 1.500
ESPP Two [Member] | Common Stock [Member]
Equity [Line Items]
Date of Issuance	July 1, 2012
Shares of common stock	135,592
Dollars Amount of Consideration	54
Price per Share or Exercise Price per Share	$ 0.400
Registered Direct Transaction Eight [Member] | Common Stock [Member]
Equity [Line Items]
Date of Issuance	December 18, 2012
Shares of common stock	15,156,250
Dollars Amount of Consideration	22,513
Price per Share or Exercise Price per Share	$ 1.600
Exercise of Warrants One [Member] | Common Stock [Member]
Equity [Line Items]
Date of Issuance	Various - 2012
Shares of common stock	8,433,003
Dollars Amount of Consideration	16,551
Price per Share or Exercise Price per Share	$ 1.970
Exercise of Stock Options Transaction Five [Member] | Common Stock [Member]
Equity [Line Items]
Date of Issuance	Various - 2012
Shares of common stock	25,937
Dollars Amount of Consideration	$ 21
Price per Share or Exercise Price per Share	$ 0.810