Business Combination - Summary of Total Fair Value Consideration (Details) $ in Thousands	Dec. 12, 2018 USD ($) shares
Business Acquisition [Line Items]
Total fair value consideration	$ 527,754
Keryx Biopharmaceuticals, Inc.
Business Acquisition [Line Items]
Total fair value consideration	$ 527,754
Keryx Biopharmaceuticals, Inc. | Akebia Shares
Business Acquisition [Line Items]
Shares issued (in shares) | shares	57,773,090
Total fair value consideration	$ 516,492
Keryx Biopharmaceuticals, Inc. | Akebia RSUs
Business Acquisition [Line Items]
RSU / Options issued (in shares) | shares	602,752
Total fair value consideration	$ 304
Keryx Biopharmaceuticals, Inc. | Akebia Stock Options
Business Acquisition [Line Items]
RSU / Options issued (in shares) | shares	3,967,290
Total fair value consideration	$ 10,958