Cover Page - USD ($)	12 Months Ended
	Dec. 31, 2019	Mar. 31, 2020	Jun. 30, 2019
Document and Entity Information:
Document Type	10-K
Document Annual Report	true
Document Transition Report	false
Document Fiscal Period Focus	FY
Entity File Number	000-53912
Entity Registrant Name	HARTMAN SHORT TERM INCOME PROPERTIES XX, INC.
Entity Incorporation, State or Country Code	MD
Entity Address, Address Line One	2909 Hillcroft
Entity Address, Address Line Two	Suite 420
Entity Address, City or Town	Houston
Entity Address, State or Province	TX
Entity Tax Identification Number	26-3455189
Entity Address, Postal Zip Code	77057
City Area Code	713
Local Phone Number	467-2222
Entity Well-known Seasoned Issuer	No
Document Period End Date	Dec. 31, 2019
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Non-accelerated Filer
Entity Small Business	true
Entity Emerging Growth Company	true
Entity Shell Company	false
Amendment Flag	false
Entity Central Index Key	0001446687
Current Fiscal Year End Date	--12-31
Entity Common Stock, Shares Outstanding		18,417,687
Entity Public Float			$ 0
Entity Ex Transition Period	false
Document Fiscal Year Focus	2019