Cover page - USD ($)	12 Months Ended
	Dec. 31, 2019	Mar. 09, 2020	Jun. 30, 2019
Cover page.
Document Type	10-K
Amendment Flag	false
Document Period End Date	Dec. 31, 2019
Document Fiscal Year Focus	2019
Document Fiscal Period Focus	FY
Title of 12(b) Security	Common stock, par value $0.0001 per share
Trading Symbol	ZSAN
Entity Registrant Name	ZOSANO PHARMA CORPORATION
Entity Central Index Key	0001587221
Current Fiscal Year End Date	--12-31
Entity Well-known Seasoned Issuer	No
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Non-accelerated Filer
Entity Emerging Growth Company	true
Entity Ex Transition Period	true
Entity Small Business	true
Entity Shell Company	false
Entity Public Float			$ 50,924,289
Entity Common Stock, Shares Outstanding		54,338,912