Agreements - Roche (Details) - USD ($) $ in Thousands	1 Months Ended		3 Months Ended
	Jan. 31, 2019	May 31, 2000	Mar. 31, 2019	Mar. 31, 2018
Collaborative Agreements disclosures
Non-cash royalty revenue related to sale of future royalties			$ 8,488	$ 7,190
Non-cash royalty revenue related to the sale of future royalties			8,488	7,190
Roche
Collaborative Agreements disclosures
Period in arrears to receive royalty reports and payments related to sales of Kadcyla		3 months
Percentage of royalty payments	100.00%
Roche | Kadcyla
Collaborative Agreements disclosures
Non-cash royalty revenue related to sale of future royalties			8,500	7,200
Non-cash royalty revenue related to the sale of future royalties			$ 8,500	$ 7,200
OMERS | Kadcyla
Collaborative Agreements disclosures
Non-cash royalty revenue related to sale of future royalties	$ 65,200
Non-cash royalty revenue related to the sale of future royalties	$ 65,200
Percentage of royalty payments	100.00%