Acquisition - Additional Information (Details) - USD ($) $ in Thousands	1 Months Ended	6 Months Ended
	May 31, 2017	Jun. 30, 2017
Noncash Or Part Noncash Acquisitions [Line Items]
Deferred tax assets		$ 22,200
Deferred tax liabilities		100
Deferred credit		$ 21,420
NephroGenex, Inc.
Noncash Or Part Noncash Acquisitions [Line Items]
Bankruptcy proceedings unsecured claim in exchange of common stock percentage	100.00%
Consideration paid	$ 1,200
Intangible assets	500
Deferred tax assets	22,200
Tax effected net operating losses	21,100
Tax effected net operating losses, valuation allowance	7,600
Tax effected capitalized research and development expenses	8,500
Tax effected federal tax credits	1,400
Tax effected federal tax credits, valuation allowance	1,200
Deferred tax liabilities	100
Deferred credit	$ 21,400