Collaborative Arrangements and Licensing Agreements, Satellite Company Collaborations - Regulus Therapeutics Inc. (Details) $ in Thousands, shares in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2016 USD ($) shares	Sep. 30, 2016 USD ($)	Jun. 30, 2016 USD ($)	Mar. 31, 2016 USD ($)	Dec. 31, 2015 USD ($)	Sep. 30, 2015 USD ($)	Jun. 30, 2015 USD ($)	Mar. 31, 2015 USD ($)	Dec. 31, 2016 USD ($) Drug shares	Dec. 31, 2015 USD ($)	Dec. 31, 2014 USD ($)
Collaborative Arrangement and Licensing Agreement [Abstract]
Revenue earned	$ 160,349	$ 110,927	$ 38,470	$ 36,874	$ 51,571	$ 49,121	$ 120,428	$ 62,583	$ 346,620	$ 283,703	$ 214,161
Net carrying value	$ 2,414				$ 24,792				$ 2,414	24,792
Regulus Therapeutics Inc. [Member]
Collaborative Arrangement and Licensing Agreement [Abstract]
Number of drugs currently in development | Drug									3
Revenue earned									$ 0	0	0
Proceeds from sale of stock									$ 4,467	25,527	22,949
Gain on sale of stock										$ 20,211	$ 19,902
Common stock owned (in shares) | shares	1.1								1.1
Net carrying value	$ 2,414								$ 2,414