Distribution of Aerpio Therapeutics, Inc. - Additional Information (Detail)	0 Months Ended
	Dec. 22, 2011
Subsidiary or Equity Method Investee [Line Items]
Conversion basis for stock	Aerpio shares were then distributed to the Company's shareholders as a distribution on the basis of 1 share of Aerpio Series A Preferred Stock for every 35 shares of Akebia Series A Preferred Stock owned, 1 share of Aerpio Series A Preferred Stock for every 100 shares of Akebia Series B Preferred Stock owned, and 1 share of Aerpio Common Stock for every 175 shares of Akebia Common Stock owned
Series A redeemable convertible preferred stock [Member] | Akebia Therapeutics, Inc. [Member]
Subsidiary or Equity Method Investee [Line Items]
Conversion of stock, shares converted	35
Series B redeemable convertible preferred stock [Member] | Akebia Therapeutics, Inc. [Member]
Subsidiary or Equity Method Investee [Line Items]
Conversion of stock, shares converted	100
Series C redeemable convertible preferred stock [Member] | Akebia Therapeutics, Inc. [Member]
Subsidiary or Equity Method Investee [Line Items]
Conversion of stock, shares converted	175