Segment Reporting - Reconciliation (Details) - USD ($) $ in Thousands		3 Months Ended		6 Months Ended
		Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017		Jun. 30, 2016
Segment Reporting Information [Line Items]
Income before income tax expense	[1],[2]	$ 5,080	$ 23,729	$ 18,617		$ 40,458
Interest and other income	[1],[2]	265	(195)	66		(100)
Interest expense	[1],[2]	2,452	832	5,897		1,585
Operating Income	[1],[2]	7,797	24,366	24,580		41,943
Depreciation and amortization	[1],[2]	9,656	8,253	18,926		15,042
General and administrative	[1],[2],[3]	19,346	19,799	43,839		37,179
Less:
Net asset optimization (expense)/revenues	[1],[2],[4]	(168)	(677)	(361)		(150)
Net, (loss) gain on non-trading derivative instruments		(9,677)	13,245	(31,473)		3,496
Net, Cash settlements on non-trading derivative instruments				11,828	[5]	15,829	[6]
Retail Gross Margin		43,149	38,820	107,749		78,382
Non-trading
Less:
Net, (loss) gain on non-trading derivative instruments		(10,202)	13,322	(31,578)		3,702
Net, Cash settlements on non-trading derivative instruments		$ 4,020	$ 953	$ 11,535		$ 12,230

[1] Financial information has been recast to include results attributable to the acquisition of Perigee Energy, LLC by an affiliate on February 3, 2017. See Notes 2 and 3 "Basis of Presentation and Summary of Significant Accounting Policies" and "Acquisitions" for further discussion.

[2] Financial information has been recast to include results attributable to the acquisition of the Major Energy Companies by an affiliate on April 15, 2016. See Note 2 and 3 "Basis of Presentation and Summary of Significant Accounting Policies" and "Acquisitions" for further discussion.

[3] General and administrative includes general and administrative expense—affiliates of $6,100 and $4,000 for the three months ended June 30, 2017 and 2016, respectively, and $13,400 and $8,400 for the six months ended June 30, 2017 and 2016, respectively.

[4] Net asset optimization revenues (expenses) includes asset optimization revenues—affiliates of $0 and $41 for the three months ended June 30, 2017 and 2016, respectively, and asset optimization revenues—affiliates cost of revenues of $0 and $376 for the three months ended June 30, 2017 and 2016, respectively, and asset optimization revenues—affiliates of $0 and $154 for the six months ended June 30, 2017 and 2016, respectively, and asset optimization revenue—affiliates cost of revenues of $0 and $1,633 for the six months ended June 30, 2017 and 2016, respectively.

[5] Financial information has been recast to include results attributable to the acquisition of Perigee Energy, LLC by an affiliate on February 3, 2017. See Notes 2 and 3 "Basis of Presentation and Summary of Significant Accounting Policies" and "Acquisitions," respectively, for further discussion.

[6] Financial information has been recast to include results attributable to the acquisition of the Major Energy Companies by an affiliate on April 15, 2016. See Notes 2 and 3 "Basis of Presentation and Summary of Significant Accounting Policies" and "Acquisitions," respectively, for further discussion.