Acquisitions - Acquisition of Major Energy Companies - Narrative (Details) $ / shares in Units, $ in Thousands		6 Months Ended	12 Months Ended
	Aug. 23, 2016 USD ($) utility $ / shares shares	Jun. 30, 2017 USD ($) shares	Dec. 31, 2016 USD ($)	Aug. 01, 2016 $ / shares
Combination of Entities under Common Control, by Combination [Line Items]
Amount recorded as equity transaction		$ (210)
National Gas & Electric, LLC
Combination of Entities under Common Control, by Combination [Line Items]
Amount recorded as equity transaction		(1,400)
Common Class B
Combination of Entities under Common Control, by Combination [Line Items]
Share price (in dollars per share) | $ / shares	$ 10			$ 10
Major Energy Companies
Combination of Entities under Common Control, by Combination [Line Items]
Employment contract termination costs		1,900	$ 4,100
Employee contract termination liability		2,200
Major Energy Companies | National Gas & Electric, LLC
Combination of Entities under Common Control, by Combination [Line Items]
Initial working capital estimate	$ 10,300
Major Energy Companies
Combination of Entities under Common Control, by Combination [Line Items]
Number of utilities | utility	43
Consideration amount	$ 63,400
Working capital	4,300
Litigation reserve	5,000
Installment and earnout payments (up to)	35,000
Installment and earnout payments purchase date value	13,100
Amount recorded as equity transaction	$ (6,000)	(4,900)	$ (4,700)
Major Energy Companies | Common Class B
Combination of Entities under Common Control, by Combination [Line Items]
Share earnout maximum (in shares) | shares	81,436
Value of shares for earnout	$ 800	$ 800
Number of shares issued for acquisition (shares) | shares	4,000,000
Value of shares issued for acquisition	$ 40,000
Major Energy Companies | Common Class B | Maximum
Combination of Entities under Common Control, by Combination [Line Items]
Share earnout maximum (in shares) | shares	400,000	400,000
Major Energy Companies | Major Energy Companies
Combination of Entities under Common Control, by Combination [Line Items]
Working capital	$ 4,300