Distribution of Aerpio Therapeutics, Inc. - Summary of Activities Included in Statements of Operations and Comprehensive Loss (Details) (USD $)	3 Months Ended		9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Subsidiary or Equity Method Investee [Line Items]
Reimbursement from Aerpio for Akebia employee costs	$ 180,000	$ 238,000	$ 544,000	$ 816,000
Aerpio Therapeutics, Inc.
Subsidiary or Equity Method Investee [Line Items]
Reimbursement from Aerpio for Akebia employee costs	180,132	238,107	544,471	815,704
Facility-related charges from Aerpio	$ 10,914	$ 2,601	$ 58,250	$ 186,518