Stockholders' Equity, Stock-based Compensation Expense (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Stock-Based Compensation [Abstract]
Stock-based compensation expense	$ 85,975	$ 72,108	$ 59,314
Research, Development and Patent [Member]
Stock-Based Compensation [Abstract]
Stock-based compensation expense	64,521	55,099	43,638
Selling, General and Administrative [Member]
Stock-Based Compensation [Abstract]
Stock-based compensation expense	21,454	17,009	15,676
Akcea Therapeutics [Member]
Stock-Based Compensation [Abstract]
Stock-based compensation expense	$ 17,500	$ 10,100	$ 6,500