Business Combination - Summary of Total Fair Value Consideration (Details) - USD ($) $ in Thousands		3 Months Ended
	Dec. 12, 2018	Mar. 31, 2019
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]
Total fair value consideration	516,492
Keryx Biopharmaceuticals, Inc. | Akebia RSUs | Precombination Employee Services
Business Acquisition [Line Items]
Total fair value consideration	304
Keryx Biopharmaceuticals, Inc. | Akebia Stock Options | Precombination Employee Services
Business Acquisition [Line Items]
Total fair value consideration	$ 10,958