Intangible Assets and Goodwill - Intangible Assets (Detail) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011
Product Rights [Line Items]
Gross Amount	$ 228,468	$ 58,678
Accumulated Amortization	(25,802)	(17,024)
2011 Foreign Currency Translation	(355)
Net Amount	202,311	41,654
FUSILEV [Member]
Product Rights [Line Items]
Gross Amount	16,778	16,778
Accumulated Amortization	(2,980)	(1,009)
Net Amount	13,798	15,769
Weighted Average Amortization Period (years)	7 years	8 years
ZEVALIN [Member] | US [Member]
Product Rights [Line Items]
Gross Amount	41,900	41,900
Accumulated Amortization	(19,735)	(16,015)
Net Amount	22,165	25,885
Weighted Average Amortization Period (years)	6 years	7 years
FOLOTYN [Member]
Product Rights [Line Items]
Gross Amount	27,900
Accumulated Amortization	(895)
Net Amount	27,005
Weighted Average Amortization Period (years)	9 years 3 months 18 days
FOLOTYN [Member] | United States & Canada [Member]
Product Rights [Line Items]
Gross Amount	118,400
Net Amount	118,400
ZEVALIN Rights [Member]
Product Rights [Line Items]
Gross Amount	23,490
Accumulated Amortization	(2,192)
2011 Foreign Currency Translation	(355)
Net Amount	$ 20,943
Weighted Average Amortization Period (years)	9 years 6 months