Subsequent Events - Lesinurad License Agreement Termination - Workforce Reduction (Details) - Subsequent Event - Reduction in Workforce, Termination of Lesinurad License Agreement, August 2, 2018 $ in Millions	Aug. 02, 2018 USD ($) employee
Workforce Reduction
Number of employees expected to be eliminated | employee	125
One-time Termination Benefits | Minimum
Workforce Reduction
Expected cost	$ 9.0
One-time Termination Benefits | Maximum
Workforce Reduction
Expected cost	11.0
Contract Termination | Minimum
Workforce Reduction
Expected cost	1.0
Contract Termination | Maximum
Workforce Reduction
Expected cost	$ 2.0