Basis of Presentation and Summary of Significant Accounting Policies - Accounting Policies Narrative (Details) - USD ($)	1 Months Ended		3 Months Ended	12 Months Ended
	Dec. 31, 2020	Jun. 30, 2020	Dec. 31, 2020	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Accounting Policies [Abstract]
Customer acquisition costs	$ 6,100,000		$ 6,100,000	$ 6,100,000	$ 18,500,000
Customer acquisition costs, current	5,800,000		5,800,000	5,800,000	8,700,000
Customer acquisition costs, noncurrent	306,000		306,000	306,000	9,845,000
Amortization of acquisition costs				13,900,000	18,500,000	$ 24,400,000
Finite-Lived Intangible Assets [Line Items]
Intangible assets, current	12,077,000		12,077,000	12,077,000	13,607,000
Intangible assets, non-current	5,691,000		5,691,000	5,691,000	17,767,000
Intangible assets	22,366,000		22,366,000	22,366,000
Operating lease expense				400,000	800,000
Operating leases, rent expense						800,000
Sublease income				200,000	400,000	0
Goodwill impairment			0
Asset optimization revenue				24,800,000	62,800,000	113,700,000
Asset optimization cost of revenues				25,500,000	60,000,000.0	109,200,000
Starion Acquisition
Finite-Lived Intangible Assets [Line Items]
Restricted cash	0		0	0	1,000,000.0
Release of escrow	100,000	$ 1,000,000.0
Other current assets
Finite-Lived Intangible Assets [Line Items]
Right-of-use assets	100,000		100,000	100,000	400,000
Gas balancing receivable (payable)	300,000		300,000	300,000	1,600,000
Other current liabilities
Finite-Lived Intangible Assets [Line Items]
Lease liabilities	200,000		200,000	200,000	600,000
Gas balancing receivable (payable)	$ (100,000)		$ (100,000)	$ (100,000)	(100,000)
Minimum
Finite-Lived Intangible Assets [Line Items]
Property lease term	3 years		3 years	3 years
Property and equipment estimated useful lives				2 years
Maximum
Finite-Lived Intangible Assets [Line Items]
Property lease term	5 years		5 years	5 years
Property and equipment estimated useful lives				5 years
Customer relationships
Finite-Lived Intangible Assets [Line Items]
Amortization expense				$ 13,600,000	18,300,000	20,300,000
Impairment charges				0	0	0
Customer relationships | Major Energy Companies, Provider Companies, And Verde Companies
Finite-Lived Intangible Assets [Line Items]
Amortization expense				9,300,000	16,500,000
Customer relationships | Retail cost of revenue | Major Energy Companies, Provider Companies, And Verde Companies
Finite-Lived Intangible Assets [Line Items]
Amortization expense				$ 0	100,000	1,200,000
Customer relationships | Minimum
Finite-Lived Intangible Assets [Line Items]
Amortization period				3 years
Customer relationships | Maximum
Finite-Lived Intangible Assets [Line Items]
Amortization period				6 years
Non-compete agreements
Finite-Lived Intangible Assets [Line Items]
Amortization period				3 years
Amortization expense				$ 0	300,000	1,100,000
Trademarks
Finite-Lived Intangible Assets [Line Items]
Amortization expense				1,110,000	1,579,000	1,271,000
Impairment charges				0	0	0
Intangible assets	$ 4,598,000		$ 4,598,000	$ 4,598,000	$ 5,708,000	$ 7,287,000	$ 8,558,000
Trademarks | Minimum
Finite-Lived Intangible Assets [Line Items]
Amortization period				5 years
Trademarks | Maximum
Finite-Lived Intangible Assets [Line Items]
Amortization period				10 years