Composition of Total Revenue - Schedule of Net Product Sales by Source (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Revenue, Major Customer [Line Items]
License fees and service revenue	$ 29,402	$ 25,268	$ 24,168	$ 30,495	$ 28,570	$ 36,395	$ 34,301	$ 29,101	$ 109,333	$ 128,367	$ 146,444
Sales Revenue, Services, Net [Member]
Revenue, Major Customer [Line Items]
Percentage of sales									100.00%	100.00%	100.00%
License and Service [Member]
Revenue, Major Customer [Line Items]
License fees and service revenue									$ 4,867	$ 12,189	$ 17,848
ZEVALIN, in Asia and Certain Other Territories, Excluding China [Member]
Revenue, Major Customer [Line Items]
License fees and service revenue									$ 2,001	$ 1,245	$ 1,756
ZEVALIN, in Asia and Certain Other Territories, Excluding China [Member] | Sales Revenue, Services, Net [Member]
Revenue, Major Customer [Line Items]
Percentage of sales									41.10%	10.20%	9.80%
FOLOTYN in all Countries Except the U.S., Canada, Europe, and Turkey [Member]
Revenue, Major Customer [Line Items]
License fees and service revenue									$ 1,860	$ 5,848	$ 927
FOLOTYN in all Countries Except the U.S., Canada, Europe, and Turkey [Member] | Sales Revenue, Services, Net [Member]
Revenue, Major Customer [Line Items]
Percentage of sales									38.20%	48.00%	5.20%
ZEVALIN, FOLOTYN, BELEODAQ, MARQIBO, In Canada Territory
Revenue, Major Customer [Line Items]
License fees and service revenue									$ 1,006	$ 5	$ 6,000
ZEVALIN, FOLOTYN, BELEODAQ, MARQIBO, In Canada Territory | Sales Revenue, Services, Net [Member]
Revenue, Major Customer [Line Items]
Percentage of sales									20.70%	0.00%	33.60%
ZEVALIN, in India Territory [Member]
Revenue, Major Customer [Line Items]
License fees and service revenue									$ 0	$ 50	$ 69
ZEVALIN, in India Territory [Member] | Sales Revenue, Services, Net [Member]
Revenue, Major Customer [Line Items]
Percentage of sales									0.00%	0.40%	0.40%
Sales and Marketing Contracted Services [Member]
Revenue, Major Customer [Line Items]
License fees and service revenue									$ 0	$ 4,747	$ 9,096
Sales and Marketing Contracted Services [Member] | Sales Revenue, Services, Net [Member]
Revenue, Major Customer [Line Items]
Percentage of sales									0.00%	38.90%	51.00%
Regulatory Services Provided to Licensee [Member]
Revenue, Major Customer [Line Items]
License fees and service revenue									$ 0	$ 294	$ 0
Regulatory Services Provided to Licensee [Member] | Sales Revenue, Services, Net [Member]
Revenue, Major Customer [Line Items]
Percentage of sales									0.00%	2.40%	0.00%