Document and Entity Information - shares	3 Months Ended
	Mar. 31, 2020	May 06, 2020
Cover [Abstract]
Document Type	10-Q
Amendment Flag	false
Current Fiscal Year End Date	--12-31
Document Period End Date	Mar. 31, 2020
Document Fiscal Year Focus	2020
Document Fiscal Period Focus	Q1
Trading Symbol	ARPO
Entity Filer Category	Non-accelerated Filer
Entity Small Business	true
Entity Emerging Growth Company	true
Entity Ex Transition Period	true
Entity Registrant Name	Aerpio Pharmaceuticals, Inc.
Entity Central Index Key	0001422142
Entity Common Stock, Shares Outstanding		40,588,004
Entity Shell Company	false
Entity Current Reporting Status	Yes
Entity File Number	001-38560
Entity Tax Identification Number	61-1547850
Entity Address, Address Line One	9987 Carver Road
Entity Address, City or Town	Cincinnati
Entity Address, State or Province	OH
Entity Address, Postal Zip Code	45242
City Area Code	513
Local Phone Number	985-1920
Entity Interactive Data Current	Yes
Title of 12(b) Security	Common stock, $0.0001 par value per share
Security Exchange Name	NASDAQ
Entity Incorporation, State or Country Code	DE
Document Quarterly Report	true
Document Transition Report	false