Depreciation and Amortization, by Segment (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Property, Plant and Equipment [Line Items]
Depreciation and amortization	$ 30,907	$ 15,090	$ 61,979	$ 29,468
Electricity Operating Segment [Member]
Property, Plant and Equipment [Line Items]
Depreciation and amortization	6,419	5,774	12,944	11,085
Gas Operating Segment [Member]
Property, Plant and Equipment [Line Items]
Depreciation and amortization	4,254	4,503	8,456	8,747
Water Operating Segment [Member]
Property, Plant and Equipment [Line Items]
Depreciation and amortization	4,008	3,887	8,117	7,846
Networks Operating Segment [Member]
Property, Plant and Equipment [Line Items]
Depreciation and amortization	15,223	0	30,235	0
Corporate Unallocated [Member]
Property, Plant and Equipment [Line Items]
Depreciation and amortization	$ 1,003	$ 926	$ 2,227	$ 1,790