Document and Entity Information	9 Months Ended
	Sep. 30, 2019 shares
Cover [Abstract]
Entity Registrant Name	AMERICA FIRST MULTIFAMILY INVESTORS, L.P.
Entity Central Index Key	0001059142
Current Fiscal Year End Date	--12-31
Entity Filer Category	Accelerated Filer
Entity Small Business	true
Entity Emerging Growth Company	false
Document Type	10-Q
Document Period End Date	Sep. 30, 2019
Document Fiscal Year Focus	2019
Document Fiscal Period Focus	Q3
Amendment Flag	false
Entity Common Stock, Units Outstanding	60,835,204
Entity Shell Company	false
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity File Number	000-24843
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	47-0810385
Entity Address, Address Line One	1004 Farnam Street
Entity Address, Address Line Two	Suite 400
Entity Address, City or Town	Omaha
Entity Address, State or Province	NE
Entity Address, Postal Zip Code	68102
City Area Code	402
Local Phone Number	444-1630
Document Quarterly Report	true
Document Transition Report	false
Title of each class	Beneficial Unit Certificates representing assignments of limited partnership interests in America First Multifamily Investors, L.P.
Trading Symbol	ATAX
Name of each exchange on which registered	NASDAQ