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