Out-License of ZEVALIN in Certain Ex-U.S. Territories (Details) - ZEVALIN Ex-U.S. Distribution Rights [Member] - USD ($) $ in Millions		1 Months Ended			2 Months Ended	3 Months Ended
	Jun. 30, 2017	Apr. 30, 2018	Jan. 31, 2016	Dec. 31, 2015	Jan. 31, 2016	Dec. 31, 2015
Payment One [Member]
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Total consideration received				$ 15
Payment Two [Member]
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Total consideration received			$ 3
Total Consideration [Member]
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Total consideration received					$ 18
License and Service [Member]
Research and Development Arrangement, Contract to Perform for Others [Line Items]
License fees and service revenue		$ 2
License and Service [Member] | Payment Two [Member]
Research and Development Arrangement, Contract to Perform for Others [Line Items]
License fees and service revenue	$ 3
License and Service [Member] | Total Consideration [Member]
Research and Development Arrangement, Contract to Perform for Others [Line Items]
License fees and service revenue						$ 15