Revenue Recognition - Narrative (Details) - USD ($)	3 Months Ended								12 Months Ended			27 Months Ended
	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2019
Disaggregation of Revenue [Line Items]
Prior period performance obligation revenue recognized									$ 24,800,000	$ 22,800,000	$ 66,000,000.0
Overpayment reimbursement liability	$ 27,300,000				$ 35,900,000				27,300,000	35,900,000		$ 27,300,000
Revenue recognized												0
Total revenues	224,344,000	$ 228,772,000	$ 226,368,000	$ 222,451,000	221,852,000	$ 249,815,000	$ 263,685,000	$ 254,914,000	901,935,000	990,266,000	966,006,000
Contract liability	$ 21,800,000				$ 91,100,000				21,800,000	91,100,000		$ 21,800,000
Rayaldee
Disaggregation of Revenue [Line Items]
Revenue recognized									31,400,000	20,300,000
Total revenues									73,965,000	36,715,000
Transfer of intellectual property and other
Disaggregation of Revenue [Line Items]
Total revenues									73,317,000	69,906,000	75,537,000
Pfizer | Transfer of intellectual property and other
Disaggregation of Revenue [Line Items]
Total revenues									$ 66,800,000	60,000,000.0	61,200,000
Tesaro | Transfer of intellectual property and other
Disaggregation of Revenue [Line Items]
Revenue recognized											$ 10,000,000.0
Vifor Fresenius Medical Care Pharma Ltd | Transfer of intellectual property and other
Disaggregation of Revenue [Line Items]
Total revenues										$ 2,000,000.0