Depreciation and Amortization, by Segment (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Property, Plant and Equipment [Line Items]
Depreciation and amortization	$ 31,072	$ 14,378
Electricity Operating Segment [Member]
Property, Plant and Equipment [Line Items]
Depreciation and amortization	6,525	5,311
Gas Operating Segment [Member]
Property, Plant and Equipment [Line Items]
Depreciation and amortization	4,202	4,244
Water Operating Segment [Member]
Property, Plant and Equipment [Line Items]
Depreciation and amortization	4,109	3,959
Networks Operating Segment [Member]
Property, Plant and Equipment [Line Items]
Depreciation and amortization	15,012	0
Corporate Unallocated [Member]
Property, Plant and Equipment [Line Items]
Depreciation and amortization	$ 1,224	$ 864