Organization and Significant Accounting Policies, Noncontrolling Interest in Akcea Therapeutics, Inc. (Details) - Akcea [Member]	3 Months Ended	6 Months Ended	12 Months Ended
	Mar. 31, 2017	Jun. 30, 2017	Dec. 31, 2016	Dec. 31, 2018	Mar. 31, 2018	Jul. 31, 2017
Noncontrolling Interest in Akcea Therapeutics, Inc. [Abstract]
Percentage ownership before IPO	100.00%	100.00%	100.00%
Percentage ownership				75.00%	68.00%	68.00%