Commitments and Contingencies - Additional Information (Detail) $ in Thousands, € in Millions									1 Months Ended								3 Months Ended			12 Months Ended
	Apr. 26, 2016 USD ($) shares	Jan. 08, 2016 USD ($)	Nov. 16, 2015 USD ($)	Oct. 27, 2015 USD ($)	Dec. 17, 2014 USD ($)	Jun. 27, 2014	Jun. 19, 2014 ANDA defendant	Jul. 17, 2013 USD ($)	Jan. 31, 2016 USD ($)	Dec. 31, 2015 USD ($)	Feb. 28, 2015 USD ($)	Feb. 28, 2014 USD ($)	Apr. 30, 2012 EUR (€)	Feb. 28, 2010	Nov. 30, 2009 USD ($)	Oct. 31, 2008 USD ($) shares	Mar. 31, 2016 USD ($)	Dec. 31, 2015 USD ($)	Mar. 31, 2014 USD ($)	Dec. 31, 2016 USD ($) Country shares	Dec. 31, 2015 USD ($)	Dec. 31, 2014 USD ($)	Dec. 31, 2010 USD ($)	Apr. 30, 2016 USD ($)	Nov. 30, 2014 USD ($)	Jul. 31, 2013 USD ($)	May 31, 2006 USD ($)
Long-term Purchase Commitment [Line Items]
Rental expense																				$ 1,500	$ 1,700	$ 1,900
Potential milestone achievement										$ 100								$ 100		100	100
Deferred Revenue										6,513								6,513		$ 3,511	6,513
Amount receivable on approval of oral form of FUSILEV																											$ 200
Percentage of royalty on annual worldwide sales under condition one																				20.00%
Ligand Contingent Consideration (Note 10 (b))										5,227								5,227		$ 0	5,227
Additional license fees																				$ 60,000
Percentage of royalties on net sale of licensed products																				20.00%
Acquisition-related contingent obligations, less current portion										1,439								1,439		$ 1,315	1,439
Stock issued (shares) | shares																				10,890,915
Consideration paid under agreement (shares)												$ 1,000
Proceeds from stock																				$ 73,869	0	0
Cash paid for income taxes																				11	335	$ 329
Deferrals and contributions										6,500								6,500		8,400	6,500
Allergan [Member]
Long-term Purchase Commitment [Line Items]
Up-front non-refundable payment																$ 41,500
License costs																$ 300
Nippon Kayaku [Member]
Long-term Purchase Commitment [Line Items]
Upfront fee															$ 15,000
Payment related to agreement																				10,000
Payment on achievement of commercialization milestones																				126,000
TopoTarget [Member]
Long-term Purchase Commitment [Line Items]
Potential milestone achievement																				278,000
Upfront fee																							$ 30,000
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
Aggregate payout value																			$ 17,800
Second milestone payment																									$ 25,000
Common Class A [Member] | Allergan [Member]
Long-term Purchase Commitment [Line Items]
Stock issued (shares) | shares																25,000
Common stock issued under an at-market-issuance sales agreement (Note 7)																$ 100
FOLOTYN ANDA [Member]
Long-term Purchase Commitment [Line Items]
Number of defendants | defendant							5
Number of abbreviated new drug applications | ANDA							4
Perry Versus Spectrum [Member]
Long-term Purchase Commitment [Line Items]
Settlement				$ 7,000
Milestone Payments [Member]
Long-term Purchase Commitment [Line Items]
Milestone payments								$ 5,000												60,000
Milestone net sales achievement								30,000
Ligand Contingent Consideration (Note 10 (b))																	$ 6,000			$ 7,700				$ 6,000
FOLOTYN [Member]
Long-term Purchase Commitment [Line Items]
Percentage of royalty on annual worldwide sales under condition one																				8.00%
Percentage of royalty on annual worldwide sales under condition two																				9.00%
Percentage of royalty on annual worldwide sales under condition three																				11.00%
FOLOTYN [Member] | Minimum [Member]
Long-term Purchase Commitment [Line Items]
Amount of annual worldwide sales on which royalty is payable under condition two																				$ 150,000
Amount of annual worldwide sales on which royalty is payable under condition three																				300,000
FOLOTYN [Member] | Maximum [Member]
Long-term Purchase Commitment [Line Items]
Amount of annual worldwide sales on which royalty is payable under condition one																				150,000
Amount of annual worldwide sales on which royalty is payable under condition two																				300,000
ZEVALIN [Member]
Long-term Purchase Commitment [Line Items]
Milestone payments																				$ 5,000
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 on net sales													20.00%							20.00%
Term																				15 years
Up-front non-refundable payment					$ 500
License fee and service revenue																				$ 3,000
Talon Therapeutics, Inc. [Member]
Long-term Purchase Commitment [Line Items]
Acquisition-related contingent obligations, less current portion										1,400								1,400		1,300	$ 1,400
Contingent value rights future cash payments								$ 195,000																		$ 195,000
SPI-2012 [Member]
Long-term Purchase Commitment [Line Items]
Milestone payments																	1,900
Potential milestone achievement																				238,000
SPI-2012 [Member]
Long-term Purchase Commitment [Line Items]
Milestone payments	$ 2,700
Issued for services (shares) | shares	318,750
Proceeds from stock	$ 2,300
Cash paid for income taxes	$ 400
Poziotinib [Member] | Licensing Agreements [Member]
Long-term Purchase Commitment [Line Items]
Milestone net sales achievement											$ 358,000
Zevalin Rights [Member]
Long-term Purchase Commitment [Line Items]
Potential payment			$ 2,000
Zevalin Rights [Member] | Total Consideration [Member]
Long-term Purchase Commitment [Line Items]
Total consideration received			$ 18,000
Milestone net sales achievement																		$ 15,000		1,800
Deferred Revenue																				1,300
Zevalin Rights [Member] | Payment One [Member]
Long-term Purchase Commitment [Line Items]
Total consideration received										$ 15,000
Zevalin Rights [Member] | Payment Two [Member]
Long-term Purchase Commitment [Line Items]
Total consideration received									$ 3,000
Milestone net sales achievement																				1,800
Deferred Revenue																				$ 1,300
ZEVALIN, FOLOTYN, BELEODAQ, And MARQIBO [Member]
Long-term Purchase Commitment [Line Items]
Total consideration received		$ 6,000															$ 6,000
INDIA | ZEVALIN [Member] | Licensing Agreements [Member]
Long-term Purchase Commitment [Line Items]
Term						15 years
Recognition period																				10 years