Stockholders' Equity, Stock-based Compensation Expense (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Stock-Based Compensation [Abstract]
Stock-based compensation expense	$ 72,108	$ 59,314	$ 31,383
Research, Development and Patents [Member]
Stock-Based Compensation [Abstract]
Stock-based compensation expense	55,099	43,638	25,843
General and Administrative [Member]
Stock-Based Compensation [Abstract]
Stock-based compensation expense	17,009	15,676	$ 5,540
Akcea Therapeutics [Member]
Stock-Based Compensation [Abstract]
Stock-based compensation expense	$ 10,100	$ 6,500