Agreements - Roche (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016	Dec. 31, 2000
Collaborative Agreements disclosures
Non-cash royalty revenue related to sale of future royalties	$ 6,503	$ 6,184	$ 20,555	$ 19,508
Roche | Kadcyla
Collaborative Agreements disclosures
Period in arrears to receive royalty reports and payments related to sales of Kadcyla					3 months
Non-cash royalty revenue related to sale of future royalties			$ 20,600	$ 19,500