Restructuring Restructuring Expected Costs - 2018 Projects (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Restructuring Cost and Reserve [Line Items]
Restructuring	$ (5,623)	$ 5,043	$ 82,242	$ 8,095
2018 Projects [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring and Related Cost, Expected Cost	100,087		100,087
Restructuring			82,087
Restructuring and Related Cost, Expected Cost Remaining	18,000		18,000
Asset Impairment and Net (Gain) Loss on Sale or Disposal [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring			624
Other Restructuring [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring			1,958
Other Restructuring [Member] | 2018 Projects [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring and Related Cost, Expected Cost	18,418		18,418
Restructuring			418
Restructuring and Related Cost, Expected Cost Remaining	18,000		18,000
Employee Severance [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring			79,660
Employee Severance [Member] | 2018 Projects [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring and Related Cost, Expected Cost	81,669		81,669
Restructuring			81,669
Restructuring and Related Cost, Expected Cost Remaining	0		0
Corporate, Non-Segment [Member] | 2018 Projects [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring and Related Cost, Expected Cost	6,091		6,091
Restructuring			6,091
Restructuring and Related Cost, Expected Cost Remaining	0		0
Water Operating Segment [Member] | 2018 Projects [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring and Related Cost, Expected Cost	22,692		22,692
Restructuring			15,692
Restructuring and Related Cost, Expected Cost Remaining	7,000		7,000
Gas Operating Segment [Member] | 2018 Projects [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring and Related Cost, Expected Cost	50,558		50,558
Restructuring			41,558
Restructuring and Related Cost, Expected Cost Remaining	9,000		9,000
Electricity Operating Segment [Member] | 2018 Projects [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring and Related Cost, Expected Cost	20,746		20,746
Restructuring			18,746
Restructuring and Related Cost, Expected Cost Remaining	$ 2,000		$ 2,000