v3.26.1
Cover
Jul. 13, 2026
Cover [Abstract]  
Document Type 8-K
Amendment Flag false
Document Period End Date Jul. 13, 2026
Entity File Number 811-22072
Entity Registrant Name NXG Cushing® Midstream Energy Fund
Entity Central Index Key 0001400897
Entity Tax Identification Number 35-2303963
Entity Incorporation, State or Country Code DE
Entity Address, Address Line One One Energy Square
Entity Address, Address Line Two 4925 Greenville Avenue
Entity Address, Address Line Three Suite 1310
Entity Address, City or Town Dallas
Entity Address, State or Province TX
Entity Address, Postal Zip Code 75206
City Area Code 214
Local Phone Number 692-6334
Written Communications false
Soliciting Material false
Pre-commencement Tender Offer false
Pre-commencement Issuer Tender Offer false
Title of 12(b) Security Common Shares of Beneficial Interest
Trading Symbol SRV
Security Exchange Name NYSE
Entity Emerging Growth Company false