Income Taxes - Additional Information (Details) - USD ($) $ in Millions	1 Months Ended	3 Months Ended		6 Months Ended
	May 31, 2017	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Income Tax Disclosure [Line Items]
Effective income tax rate		33.40%	39.40%	36.00%	40.60%
U.S. statutory rate		35.00%		35.00%
Deferred tax assets				$ 22.2
Deferred tax liabilities				$ 0.1
NephroGenex, Inc.
Income Tax Disclosure [Line Items]
Deferred tax assets	$ 22.2
Tax effected net operating losses	21.1
Tax effected net operating losses, valuation allowance	7.6
Tax effected capitalized research and development expenses	8.5
Tax effected federal tax credits	1.4
Tax effected federal tax credits, valuation allowance	1.2
Deferred tax liabilities	$ 0.1