Fair Value Measurements (Details) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	[1]	Dec. 31, 2015
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Increase in estimate of CenStar Earnout	$ 1,000	$ 0
Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Increase in estimate of CenStar Earnout	1,000
Fair Value, Measurements, Recurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets	3,144			$ 605
Derivative liabilities	(2,387)			(11,238)
Contingent payment arrangement	(1,500)			(500)
Fair Value, Measurements, Recurring | Non-trading Commodity Contract
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets	3,133			200
Derivative liabilities	(2,387)			(10,985)
Fair Value, Measurements, Recurring | Trading Commodity Contract
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets	11			405
Derivative liabilities	0			(253)
Fair Value, Measurements, Recurring | Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets	243			0
Derivative liabilities	0			(3,324)
Contingent payment arrangement	0			0
Fair Value, Measurements, Recurring | Level 1 | Non-trading Commodity Contract
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets	243			0
Derivative liabilities	0			(3,324)
Fair Value, Measurements, Recurring | Level 1 | Trading Commodity Contract
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets	0			0
Derivative liabilities	0			0
Fair Value, Measurements, Recurring | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets	2,901			605
Derivative liabilities	(2,387)			(7,914)
Contingent payment arrangement	0			0
Fair Value, Measurements, Recurring | Level 2 | Non-trading Commodity Contract
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets	2,890			200
Derivative liabilities	(2,387)			(7,661)
Fair Value, Measurements, Recurring | Level 2 | Trading Commodity Contract
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets	11			405
Derivative liabilities	0			(253)
Fair Value, Measurements, Recurring | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets	0			0
Derivative liabilities	0			0
Contingent payment arrangement	(1,500)			(500)
Fair Value, Measurements, Recurring | Level 3 | Non-trading Commodity Contract
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets	0			0
Derivative liabilities	0			0
Fair Value, Measurements, Recurring | Level 3 | Trading Commodity Contract
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets	0			0
Derivative liabilities	$ 0			$ 0

[1] Financial information has been recast to include results attributable to the acquisition of Oasis Power Holdings LLC from an affiliate on May 12, 2015. See Note 2 "Basis of Presentation" for further discussion.