Business Combination - Total Consideration (Details) $ in Thousands	Dec. 12, 2018 USD ($) shares	Dec. 11, 2018
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. | Merger Agreement
Business Acquisition [Line Items]
Outstanding common stock and awards converted into right to receive shares and awards, ratio	0.37433	0.37433
Total fair value consideration	$ 527,800
Keryx Biopharmaceuticals, Inc. | Akebia Shares
Business Acquisition [Line Items]
Total fair value consideration	$ 516,492
Shares issued (in shares) | shares	57,773,090
Keryx Biopharmaceuticals, Inc. | Akebia RSUs
Business Acquisition [Line Items]
Total fair value consideration	$ 304
RSU / Options issued (in shares) | shares	602,752
Keryx Biopharmaceuticals, Inc. | Akebia Stock Options
Business Acquisition [Line Items]
Total fair value consideration	$ 10,958
RSU / Options issued (in shares) | shares	3,967,290