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Basis of Presentation (Details) - Akcea [Member] - shares
shares in Millions
3 Months Ended
Mar. 31, 2019
Dec. 31, 2018
Apr. 30, 2018
Jul. 31, 2017
Jun. 30, 2017
Basis of Presentation [Abstract]          
Percentage ownership 76.00% 75.00% 68.00% 68.00% 100.00%
Additional shares of Akcea stock received (in shares) 2.8