Collaborative Arrangements and Licensing Agreements, Antisense Therapeutics Limited (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Collaborative Arrangement and Licensing Agreement [Abstract]
Revenue earned	$ 172,299	$ 120,911	$ 104,152	$ 110,304	$ 160,349	$ 110,927	$ 38,470	$ 36,874	$ 507,666	$ 346,620	$ 283,703
Antisense Therapeutics Limited [Member] | Maximum [Member]
Collaborative Arrangement and Licensing Agreement [Abstract]
Ownership interest percentage	10.00%				10.00%				10.00%	10.00%
Antisense Therapeutics Limited [Member]
Collaborative Arrangement and Licensing Agreement [Abstract]
Revenue earned									$ 0	$ 0	$ 0