Stockholders' Equity - Summary of Reserved Shares of Common Stock for Future Issuance (Details) - shares	Mar. 31, 2020	Dec. 31, 2019
Class of Stock [Line Items]
Common stock, shares reserved for future issuance	24,958,932	21,403,890
Warrant To Purchase Common Stock
Class of Stock [Line Items]
Common stock, shares reserved for future issuance	509,611	509,611
Common Stock Options and RSUs Outstanding
Class of Stock [Line Items]
Common stock, shares reserved for future issuance	16,107,645	12,195,031
Shares Available for Issuance Under Akebia Equity
Class of Stock [Line Items]
Common stock, shares reserved for future issuance	2,740,708	2,983,256
Shares Available for Issuance Under the ESPP
Class of Stock [Line Items]
Common stock, shares reserved for future issuance	5,600,968	5,715,992