Commitments and Contingencies - Additional Information (Detail) € in Millions								1 Months Ended					3 Months Ended				6 Months Ended		12 Months Ended
	Apr. 26, 2016 USD ($) shares	Apr. 13, 2016 USD ($)	Mar. 10, 2016 USD ($)	Nov. 16, 2015 USD ($)	Oct. 27, 2015 USD ($)	Jun. 27, 2014 USD ($)	Jun. 19, 2014 defendant ANDA	Mar. 31, 2016 USD ($)	Feb. 28, 2014 USD ($)	Apr. 30, 2012 EUR (€)	Nov. 30, 2009 USD ($)	Oct. 31, 2008 USD ($) shares	Jun. 30, 2016 USD ($) shares	Mar. 31, 2016 USD ($)	Dec. 31, 2015 USD ($)	Mar. 31, 2014 USD ($)	Jun. 30, 2016 USD ($) Country	Jun. 30, 2015 USD ($)	Dec. 31, 2010 USD ($)	Jul. 31, 2014 USD ($)	Jul. 17, 2013 USD ($)	May 31, 2006 USD ($)
Long-term Purchase Commitment [Line Items]
Potential milestone achievement													$ 100,000		$ 100,000		$ 100,000
Deferred revenue													4,211,000		6,513,000		4,211,000
Amount receivable on approval of oral form of FUSILEV																						$ 200,000
Additional license fees																	60,000,000
Acquisition-related contingent obligations, less current portion													$ 1,993,000		1,439,000		1,993,000
Common stock issued (shares) | shares													6,452,170
Consideration paid for the rights granted (shares)									$ 1,000,000
Cash paid for income taxes																	11,000	$ 332,000
Deferrals and contributions													$ 7,700,000		6,500,000		$ 7,700,000
Settlement amount					$ 7,000,000
FOLOTYN ANDA [Member]
Long-term Purchase Commitment [Line Items]
Number of defendants | defendant							5
Number of Abbreviated New Drug Applications | ANDA							4
FOLOTYN [Member]
Long-term Purchase Commitment [Line Items]
Percentage of royalty on annual worldwide sales under condition one													8.00%				8.00%
Percentage of royalty on annual worldwide sales under condition two													9.00%				9.00%
Percentage of royalty on annual worldwide sales under condition three													11.00%				11.00%
Zevalin Rights [Member]
Long-term Purchase Commitment [Line Items]
Potential payment				$ 2,000,000
ZEVALIN, FOLOTYN, BELEODAQ, And MARQIBO [Member]
Long-term Purchase Commitment [Line Items]
Total consideration received														$ 6,000,000
Total Consideration [Member] | Zevalin Rights [Member]
Long-term Purchase Commitment [Line Items]
Total consideration received				18,000,000
Milestone net sales achievement															15,000,000
Payment One [Member] | Zevalin Rights [Member]
Long-term Purchase Commitment [Line Items]
Total consideration received				15,000,000
Payment Two [Member] | Zevalin Rights [Member]
Long-term Purchase Commitment [Line Items]
Total consideration received				$ 3,000,000
Milestone net sales achievement																	$ 800,000
Deferred revenue													$ 2,200,000				2,200,000
Ligand Pharmaceuticals Inc [Member]
Long-term Purchase Commitment [Line Items]
Milestone payments			$ 6,000,000					$ 6,000,000
ZEVALIN [Member]
Long-term Purchase Commitment [Line Items]
Milestone payments																	$ 5,000,000
ZEVALIN [Member] | Licensing Agreements [Member]
Long-term Purchase Commitment [Line Items]
Minimum number of countries outside U.S. approved ZEVALIN for treatment | Country																	40
Fees paid to Bayer for acquiring licensing rights | €										€ 19
Percentage of royalty										20.00%
License agreement contractual terms										15 years
Talon Therapeutics, Inc. [Member]
Long-term Purchase Commitment [Line Items]
Acquisition-related contingent obligations, less current portion													1,900,000		$ 1,400,000		$ 1,900,000
Contingent value rights future cash payments													195,000,000				195,000,000				$ 195,000,000.0
SPI-2012 [Member]
Long-term Purchase Commitment [Line Items]
Milestone payments	$ 2,700,000	$ 1,900,000
Potential milestone achievement													$ 238,000,000				238,000,000
Issuance (shares) | shares	318,750
Cash paid for income taxes	$ 400,000
Poziotinib [Member] | Licensing Agreements [Member]
Long-term Purchase Commitment [Line Items]
Milestone net sales achievement																	$ 358,000,000
Minimum [Member]
Long-term Purchase Commitment [Line Items]
Percentage of royalty on annual worldwide sales under condition one													20.00%				20.00%
Percentage of royalties on net sale of licensed products																	20.00%
Minimum [Member] | FOLOTYN [Member]
Long-term Purchase Commitment [Line Items]
Amount of annual worldwide sales on which royalty is payable under condition two																	$ 150,000,000
Amount of annual worldwide sales on which royalty is payable under condition three																	300,000,000
Maximum [Member] | FOLOTYN [Member]
Long-term Purchase Commitment [Line Items]
Amount of annual worldwide sales on which royalty is payable under condition one																	150,000,000
Amount of annual worldwide sales on which royalty is payable under condition two																	$ 300,000,000
INDIA | ZEVALIN [Member] | Licensing Agreements [Member]
Long-term Purchase Commitment [Line Items]
Percentage of royalty																	20.00%
License agreement contractual terms						15 years
Up-front non-refundable payment						$ 500,000
Recognition period for upfront payment																	10 years
Licenses revenue																	$ 3,000,000
Allergan [Member]
Long-term Purchase Commitment [Line Items]
Up-front non-refundable payment												$ 41,500,000
License fee												300,000
Allergan [Member] | Common Class A
Long-term Purchase Commitment [Line Items]
Stock issued												$ 100,000
Common stock issued (shares) | shares												25,000
Nippon Kayaku [Member]
Long-term Purchase Commitment [Line Items]
Upfront fee											$ 15,000,000
Payment related to agreement																	10,000,000
Payment on achievement of commercialization milestones																	126,000,000
TopoTarget [Member]
Long-term Purchase Commitment [Line Items]
Potential milestone achievement													$ 278,000,000				$ 278,000,000
Upfront fee																			$ 30,000,000
Percentage of development cost																	70.00%
Percentage of development cost that is funded by TopoTarget for joint development plan																	30.00%
Additional payments based on the achievement of certain development									$ 10,000,000
Aggregate payout value																$ 17,800,000
Second milestone payment																				$ 25,000,000
Principal executive office [Member] | Nevada [Member]
Long-term Purchase Commitment [Line Items]
Facility lease, non-cancelable operating lease expiring date																	Apr. 30, 2019
Research and development facility [Member] | California [Member]
Long-term Purchase Commitment [Line Items]
Facility lease, non-cancelable operating lease expiring date																	May 31, 2019