Cover Page - shares	6 Months Ended
	Jun. 30, 2020	Aug. 03, 2020
Class of Stock [Line Items]
Document Type	10-Q
Document Quarterly Report	true
Document Transition Report	false
Entity File Number	001-36559
Entity Registrant Name	Spark Energy, Inc.
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	46-5453215
Entity Address, Address Line One	12140 Wickchester Ln
Entity Address, Address Line Two	Suite 100
Entity Address, City or Town	Houston
Entity Address, State or Province	TX
Entity Address, Postal Zip Code	77079
City Area Code	713
Local Phone Number	600-2600
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Shell Company	false
Amendment Flag	false
Document Period End Date	Jun. 30, 2020
Document Fiscal Year Focus	2020
Document Fiscal Period Focus	Q2
Entity Central Index Key	0001606268
Current Fiscal Year End Date	--12-31
Class A Common Stock
Class of Stock [Line Items]
Title of 12(b) Security	Class A common stock, par value $0.01 per share
Trading Symbol	SPKE
Security Exchange Name	NASDAQ
Entity Common Stock, Shares Outstanding		14,672,432
Class B Common Stock
Class of Stock [Line Items]
Entity Common Stock, Shares Outstanding		20,800,000
Series A Preferred Stock
Class of Stock [Line Items]
Title of 12(b) Security	8.75% Series A Fixed-to-Floating RateCumulative Redeemable Perpetual Preferred Stock, par value $0.01 per share
Trading Symbol	SPKEP
Security Exchange Name	NASDAQ
Entity Common Stock, Shares Outstanding		3,567,543