Basis of Presentation and Summary of Significant Accounting Policies - Narrative (Details) (USD $)	12 Months Ended
	Dec. 31, 2014 segment	Dec. 31, 2013	Dec. 31, 2012	Aug. 01, 2014
Accounting Policies [Abstract]
Restricted cash	$ 707,000	$ 0
Allowance for doubtful accounts	8,000,000	1,200,000
Bad debt expense	10,164,000us-gaap_ProvisionForDoubtfulAccounts	3,101,000us-gaap_ProvisionForDoubtfulAccounts	1,835,000us-gaap_ProvisionForDoubtfulAccounts
Number of operating segments	2us-gaap_NumberOfOperatingSegments
Gross receipts taxes	3,000,000us-gaap_ExciseAndSalesTaxes	3,500,000us-gaap_ExciseAndSalesTaxes	5,100,000us-gaap_ExciseAndSalesTaxes
Asset optimization revenue	284,600,000spke_AssetOptimizationRevenueGross	192,400,000spke_AssetOptimizationRevenueGross	248,600,000spke_AssetOptimizationRevenueGross
Cost of revenues	$ 282,300,000spke_CostofOtherSalesRevenue	$ 192,100,000spke_CostofOtherSalesRevenue	$ 249,700,000spke_CostofOtherSalesRevenue
Class of Stock [Line Items]
Percent of stock offered				21.82%
Common Class A
Class of Stock [Line Items]
Percent of stock offered				21.82%
Common Class B
Class of Stock [Line Items]
Percent of stock offered				78.18%
NuDevco Retail Holdings \| Spark Energy, Inc
Class of Stock [Line Items]
Percent of stock offered				21.82%
NuDevco Retail Holdings \| Spark Energy, Inc \| Common Class A
Class of Stock [Line Items]
Percent of stock offered				21.82%