Acquisitions - Acquisition of Verde - Narrative (Details) - USD ($)		12 Months Ended
	Jul. 01, 2017	Dec. 31, 2017		Dec. 31, 2016		Dec. 31, 2015	[3]	Jan. 12, 2018
Business Acquisition [Line Items]
Promissory note payable		$ 145,744,000		$ 78,370,000
Accretion on fair value of Earnout liabilities		4,108,000	[1]	$ 5,060,000	[2]	$ 0
Verde Companies
Business Acquisition [Line Items]
Total consideration	$ 91,200,000
Net working capital	20,800,000	500,000
Consideration funded	85,800,000
Payments to acquire business	6,800,000
Contingent consideration—earnout obligations incurred in connection with the Provider Companies and Major Energy Companies acquisitions	$ 5,400,000
Earnout period	18 months
Adjusted EBITDA obligation, percent	100.00%
Adjusted EBITDA obligation term	18 months
Subordinated Debt | Verde Companies
Business Acquisition [Line Items]
Contingent consideration—earnout obligations incurred in connection with the Provider Companies and Major Energy Companies acquisitions	$ 15,000,000
Revolving Credit Facility | Verde Companies
Business Acquisition [Line Items]
Contingent consideration—earnout obligations incurred in connection with the Provider Companies and Major Energy Companies acquisitions	44,000,000
Notes Payable | Verde Companies
Business Acquisition [Line Items]
Contingent consideration—earnout obligations incurred in connection with the Provider Companies and Major Energy Companies acquisitions	$ 20,000,000.0
Notes Payable | Verde Earnout Termination Note
Business Acquisition [Line Items]
Promissory note payable		5,900,000
Subsequent Event | Notes Payable | Verde Earnout Termination Note
Business Acquisition [Line Items]
Promissory note payable								$ 5,900,000
National Gas & Electric, LLC | Verde Companies
Business Acquisition [Line Items]
Increase in fair value recorded in general and administrative expense		300,000
Verde Earnout
Business Acquisition [Line Items]
Accretion on fair value of Earnout liabilities		200,000
Verde Companies
Business Acquisition [Line Items]
Contributed revenues		76,000,000
Contributed earnings		$ 1,200,000
Trademarks | Verde Companies
Business Acquisition [Line Items]
Amortization period		5 years

[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," respectively, for further discussion.

[2] Financial information has been recast to include results attributable to the acquisition of the Major Energy Companies from 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.

[3] 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 Note 2 "Basis of Presentation and Summary of Significant Accounting Policies" for further discussion.