Document and Entity Information Document - USD ($)	12 Months Ended
	Dec. 31, 2019	Feb. 29, 2020	Jun. 30, 2019
Entity Information
Document Annual Report	true
Document Transition Report	false
Entity Incorporation, State or Country Code	X1
Entity Registrant Name	FEDERAL HOME LOAN BANK OF SAN FRANCISCO
Entity Central Index Key	0001316944
Document Type	10-K
Entity File Number	000-51398
Document Period End Date	Dec. 31, 2019
Amendment Flag	false
Document Fiscal Year Focus	2019
Document Fiscal Period Focus	FY
Current Fiscal Year End Date	--12-31
Entity Well-known Seasoned Issuer	No
Entity Voluntary Filers	No
Entity Emerging Growth Company	false
Entity Small Business	false
Entity Current Reporting Status	Yes
Entity Filer Category	Non-accelerated Filer
Entity Common Stock, Shares Outstanding		31,078,364
Entity Tax Identification Number	94-6000630
Entity Address, Address Line One	333 Bush Street, Suite 2700
Entity Address, City or Town	San Francisco,
Entity Address, State or Province	CA
Entity Address, Postal Zip Code	94104
City Area Code	415
Local Phone Number	616-1000
Entity Interactive Data Current	Yes
Entity Public Float			$ 0
Entity Shell Company	false
Common Stock, Shares, Outstanding			$ 3,105,000,000