Business Combinations and Contingent Consideration - Additional Information (Detail) - USD ($) $ / shares in Units, shares in Millions			1 Months Ended	12 Months Ended
	Mar. 10, 2016	Jul. 17, 2013	Mar. 31, 2013	Dec. 31, 2015	Dec. 31, 2014	Jul. 31, 2013	Sep. 05, 2012
Business Acquisition [Line Items]
License fees received			$ 3,000,000
Royalties payout percentage on our future net sales of licensed products				20.00%
Ligand Contingent Consideration				$ 5,227,000	$ 4,901,000
IPR&D [Member]
Business Acquisition [Line Items]
Estimated cash flow period				10 years
Estimated cash flow discount rate				25.00%
Milestone Payments [Member]
Business Acquisition [Line Items]
Milestone net sales achievement		$ 5,000,000		$ 66,000,000
Milestone net sales achievement		30,000,000
Ligand Contingent Consideration				$ 6,000,000
Milestone Payment One [Member]
Business Acquisition [Line Items]
Milestone net sales achievement		10,000,000
Milestone net sales achievement		60,000,000
Milestone Payment Two [Member]
Business Acquisition [Line Items]
Milestone net sales achievement		25,000,000
Milestone net sales achievement		100,000,000
Milestone Payment Three [Member]
Business Acquisition [Line Items]
Milestone net sales achievement		50,000,000
Milestone net sales achievement		200,000,000
Milestone Payment Four [Member]
Business Acquisition [Line Items]
Milestone net sales achievement		100,000,000
Milestone net sales achievement		400,000,000
Menadione Topical Lotion [Member]
Business Acquisition [Line Items]
Milestone net sales achievement		5,000,000
Talon Therapeutics, Inc. [Member]
Business Acquisition [Line Items]
Additional shares business acquisition date				Jul. 17, 2013
Cash consideration		$ 11,300,000
Shares issued in acquisition (shares)		3.0
Common stock value assigned		$ 26,300,000
Common stock value, per share ($ per share)		$ 8.77
Estimated fair value of acquisition		$ 6,500,000
Contingent value rights future cash payments		$ 195,000,000				$ 195,000,000
Talon Therapeutics, Inc. [Member] | Minimum [Member]
Business Acquisition [Line Items]
Contingent value rights expected rate		50.00%
Talon Therapeutics, Inc. [Member] | Maximum [Member]
Business Acquisition [Line Items]
Contingent value rights expected rate		100.00%
Allos Therapeutics, Inc. [Member]
Business Acquisition [Line Items]
Ligand Contingent Consideration				$ 0
Total purchase consideration							$ 205,200,000
Subsequent Event [Member]
Business Acquisition [Line Items]
Payment period	30 days
Subsequent Event [Member] | Milestone Payments [Member]
Business Acquisition [Line Items]
Ligand Contingent Consideration	$ 6,000,000