Liability Related to the Sale of Future Royalties - Summary of Liability Related to Potential Future Royalties (Detail) - USD ($) $ in Thousands	12 Months Ended			58 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2016
Other Liabilities Disclosure [Abstract]
Liability related to the sale of future royalties—beginning balance	$ 119,032			$ 0
Proceeds from sale of future royalties	0			124,000
Payments from Nektar to RPI	0			(10,000)
Non-cash CIMZIA® and MIRCERA® royalty revenue	(30,158)	$ (22,058)	$ (21,937)	(106,999)
Non-cash interest expense recognized	19,712	20,619	$ 20,888	101,585
Liability related to the sale of future royalties – ending balance	108,586	119,032		108,586
Less: unamortized transaction costs	(2,636)			(2,636)
Liability related to the sale of future royalties, net	$ 105,950	$ 116,029		$ 105,950