Transactions with Affiliates (Details) - USD ($)		1 Months Ended	3 Months Ended		6 Months Ended
	Jul. 15, 2019	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019	Dec. 31, 2019
Related Party Transaction [Line Items]
General and administrative			$ 21,331,000	$ 37,247,000	$ 47,007,000	$ 66,723,000
Current accounts receivable - affiliates			4,148,000		4,148,000		$ 2,032,000
Current accounts payable - affiliates			717,000		717,000		1,009,000
Revenues recorded in net asset optimization revenues related to affiliates			(82,000)	(56,000)	239,000	2,496,000
Retailco and NuDevco Retail
Related Party Transaction [Line Items]
Cash payment to acquire business	$ 11,200,000
Affiliated Entity
Related Party Transaction [Line Items]
Revenues recorded in net asset optimization revenues related to affiliates			200,000	600,000	700,000	1,800,000
Spark HoldCo
Related Party Transaction [Line Items]
Distributions to affiliates	$ 16,300,000
Affiliated Entity | Subordinated Debt Facility
Related Party Transaction [Line Items]
Subordinated debt—affiliate		$ 25,000,000.0		25,000,000.0		25,000,000.0
Subordinated debt, advances		$ 1,000,000.0		1,000,000.0		1,000,000.0
Subordinated debt, interest rate on advances		5.00%
Outstanding under subordinated note		$ 0		0		0	$ 0
Affiliated Entity | Allocated Overhead Costs
Related Party Transaction [Line Items]
Affiliate expenses			200,000	400,000	100,000	400,000
General and administrative			100,000		100,000
Affiliated Entity | Purchased Natural Gas From Affiliate
Related Party Transaction [Line Items]
Cost of revenues recorded in net asset optimization revenues (less than)			100,000	100,000	300,000	100,000
NuDevco Retail Holdings and NuDevco Retail
Related Party Transaction [Line Items]
Distributions to affiliates			3,800,000	3,800,000	7,500,000	7,500,000
NuDevco Retail Holdings and NuDevco Retail | Payment of Income Taxes Incurred by the Company
Related Party Transaction [Line Items]
Distributions to affiliates			$ 2,800,000	$ 400,000	$ 6,200,000	$ 0