Fair Value Measurements (Details) - USD ($)				1 Months Ended	3 Months Ended	9 Months Ended
		Aug. 23, 2016	Apr. 15, 2016	Aug. 31, 2016	Sep. 30, 2016	Sep. 30, 2016		Sep. 30, 2015	[2]	Aug. 01, 2016	Mar. 31, 2016	Dec. 31, 2015
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Contingent consideration for acquisitions - current					$ 11,325,000	$ 11,325,000						$ 500,000
Contingent consideration for acquisitions - noncurrent					7,611,000	7,611,000						0
Earnout payments						1,343,000	[1]	$ 0
Increase in estimate of CenStar Earnout						843,000	[1]	$ 0
Fair Value, Measurements, Recurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets					1,854,000	1,854,000						605,000
Derivative liabilities					(15,229,000)	(15,229,000)						(11,238,000)
Contingent payment arrangement					18,935,000	18,935,000						500,000
Fair Value, Measurements, Recurring | Non-trading Commodity Contract
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets					915,000	915,000						200,000
Derivative liabilities					(14,896,000)	(14,896,000)						(10,985,000)
Fair Value, Measurements, Recurring | Trading Commodity Contract
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets					939,000	939,000						405,000
Derivative liabilities					(333,000)	(333,000)						(253,000)
Fair Value, Measurements, Recurring | Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets					0	0						0
Derivative liabilities					(506,000)	(506,000)						(3,324,000)
Contingent payment arrangement					0	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					0	0						0
Derivative liabilities					(448,000)	(448,000)						(3,324,000)
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						0
Derivative liabilities					(58,000)	(58,000)						0
Fair Value, Measurements, Recurring | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets					1,854,000	1,854,000						605,000
Derivative liabilities					(14,723,000)	(14,723,000)						(7,914,000)
Contingent payment arrangement					0	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					915,000	915,000						200,000
Derivative liabilities					(14,448,000)	(14,448,000)						(7,661,000)
Fair Value, Measurements, Recurring | Level 2 | Trading Commodity Contract
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets					939,000	939,000						405,000
Derivative liabilities					(275,000)	(275,000)						(253,000)
Fair Value, Measurements, Recurring | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets					0	0						0
Derivative liabilities					0	0						0
Contingent payment arrangement					18,935,000	18,935,000						500,000
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						0
Derivative liabilities					0	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						0
Derivative liabilities					0	$ 0						0
Provider Earnout
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Performance period (in years)						9 months
Earnout maximum					9,000,000	$ 9,000,000				$ 9,000,000
Earnout minimum					5,000,000	5,000,000
Provider Earnout | Fair Value, Measurements, Recurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Contingent payment arrangement					4,800,000	4,800,000
Major Earnout | Fair Value, Measurements, Recurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Contingent payment arrangement					13,300,000	$ 13,300,000
CenStar Earnout
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Contingent payment arrangement											$ 1,500,000	$ 500,000
Performance period (in years)						1 year
Earnout payments	[1]			$ (1,300,000)
Release from escrow				$ 600,000
CenStar Earnout | Fair Value, Measurements, Recurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Contingent payment arrangement					800,000	$ 800,000
General and Administrative Expense | CenStar Earnout
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Increase in estimate of CenStar Earnout	[1]				$ (200,000)	$ (200,000)
National Gas & Electric, LLC | Major Energy Companies
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Performance period (in years)			33 months
Earnout maximum			$ 20,000,000.0
Major Energy Companies | Common Class B
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Share earnout maximum (in shares)		40,718
Major Energy Companies | Common Class B | Maximum
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Share earnout maximum (in shares)		200,000

[1] Financial information has been recast to include results attributable to the acquisition of the Major Energy Companies from an affiliate on August 23, 2016. See Notes 2 and 3 "Basis of Presentation" and "Acquisitions," respectively, for further discussion.

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