Liability Related to the Sale of Future Royalties and Milestones (Narrative) (Details) - USD ($)				3 Months Ended	9 Months Ended	12 Months Ended
	Sep. 20, 2018	Jan. 19, 2018	Jan. 06, 2018	Sep. 30, 2018	Sep. 30, 2019	Dec. 31, 2019	Dec. 31, 2018
Liability Related To Sale Of Future Royalties And Milestones [Line Items]
Non-cash royalty revenue recognized						$ 30,424,000
Non-cash interest expense						41,474,000
Incyte Corporation and Merck Sharpe & Dohme [Member]
Liability Related To Sale Of Future Royalties And Milestones [Line Items]
Percentage of future milestones retained	90.00%
Percentage of future royalties retained	67.00%
GSK Agreements [Member]
Liability Related To Sale Of Future Royalties And Milestones [Line Items]
Non-cash royalty revenue recognized						30,400,000	$ 17,300,000
HCR [Member] | GSK Agreements [Member] | Royalty Purchase Agreement [Member]
Liability Related To Sale Of Future Royalties And Milestones [Line Items]
Percentage of purchase of worldwide rights to receive royalties			100.00%
Gross proceeds received for royalty rights		$ 190,000,000
Reimbursed HCR for transaction costs		100,000
Transaction costs incurred		500,000
Non-cash royalty revenue recognized						30,400,000	17,300,000
Non-cash interest expense						41,500,000	$ 23,100,000
Effective annual interest rate							23.30%
Prospective effective annual interest rate							21.60%
HCR [Member] | GSK Agreements [Member] | Royalty Purchase Agreement [Member] | Maximum [Member]
Liability Related To Sale Of Future Royalties And Milestones [Line Items]
Potential milestone payments receivable		40,400,000				15,100,000
HCR [Member] | GSK Agreements [Member] | Royalty Purchase Agreement [Member] | Prior to 2024 [Member]
Liability Related To Sale Of Future Royalties And Milestones [Line Items]
Potential milestone payments receivable		15,100,000				15,100,000
Sales milestones target			$ 2,000,000,000			$ 2,000,000,000
HCR [Member] | GSK Agreements [Member] | Royalty Purchase Agreement [Member] | Prior to 2026 [Member]
Liability Related To Sale Of Future Royalties And Milestones [Line Items]
Potential milestone payments receivable		$ 25,300,000
Sales milestones target			2,750,000,000
HCR [Member] | GSK Agreements [Member] | Royalty Purchase Agreement [Member] | 2021 [Member]
Liability Related To Sale Of Future Royalties And Milestones [Line Items]
Payables upon not achieving sales milestones			25,900,000
HCR [Member] | GSK Agreements [Member] | Royalty Purchase Agreement [Member] | 2019 [Member]
Liability Related To Sale Of Future Royalties And Milestones [Line Items]
Sales milestones target			1,000,000,000		$ 1,600,000,000
HCR [Member] | GSK Agreements [Member] | Royalty Purchase Agreement [Member] | 2020 [Member]
Liability Related To Sale Of Future Royalties And Milestones [Line Items]
Sales milestones target			$ 1,750,000,000
XOMA [Member] | Royalty Purchase Agreement [Member]
Liability Related To Sale Of Future Royalties And Milestones [Line Items]
Proceeds from royalties and milestones payment	$ 15,000,000
Liability related to sale of future royalties and milestones	$ 15,000,000
XOMA [Member] | Royalty Purchase Agreement [Member] | Incyte Corporation and Merck Sharpe & Dohme [Member]
Liability Related To Sale Of Future Royalties And Milestones [Line Items]
Percentage of sold future royalties right to receive	33.00%
Percentage of sold future milestones right to receive	10.00%
XOMA [Member] | Royalty Purchase Agreement [Member] | Incyte Corporation [Member]
Liability Related To Sale Of Future Royalties And Milestones [Line Items]
Percentage of sold future royalties right to receive	33.00%
Percentage of sold future milestones right to receive	10.00%
Proceeds from milestones recognized				$ 5,000,000