Restructuring Restructuring Expected Costs, Costs Recognized, and Remaining Costs to be Recognized - 2013 Project (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Restructuring Cost and Reserve [Line Items]
Restructuring Charges	$ 50,857	$ 35,497	$ 1,665
Employee severance costs
Restructuring Cost and Reserve [Line Items]
Restructuring Charges	41,952
Asset Impairment and Net (Gain) Loss on Sale or Disposal [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring Charges	5,220
Other restructuring costs
Restructuring Cost and Reserve [Line Items]
Restructuring Charges	3,685
2013 Project [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring and Related Cost, Expected Cost	26,156
Restructuring and Related Cost, Cost Incurred to Date		31,099
Restructuring Charges	(4,943)	31,100
Restructuring and Related Cost, Expected Cost Remaining	0
2013 Project [Member] | Employee severance costs
Restructuring Cost and Reserve [Line Items]
Restructuring and Related Cost, Expected Cost	23,691
Restructuring and Related Cost, Cost Incurred to Date		29,186
Restructuring Charges	(5,495)
Restructuring and Related Cost, Expected Cost Remaining	0
2013 Project [Member] | Asset Impairment and Net (Gain) Loss on Sale or Disposal [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring and Related Cost, Expected Cost	(1,500)
Restructuring and Related Cost, Cost Incurred to Date		1,232
Restructuring Charges	(2,732)
Restructuring and Related Cost, Expected Cost Remaining	0
2013 Project [Member] | Other restructuring costs
Restructuring Cost and Reserve [Line Items]
Restructuring and Related Cost, Expected Cost	3,965
Restructuring and Related Cost, Cost Incurred to Date		681
Restructuring Charges	3,284
Restructuring and Related Cost, Expected Cost Remaining	0
2013 Project [Member] | Electricity Operating Segment [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring and Related Cost, Expected Cost	15,512
Restructuring and Related Cost, Cost Incurred to Date		24,056
Restructuring Charges	(8,544)
Restructuring and Related Cost, Expected Cost Remaining	0
2013 Project [Member] | Gas Operating Segment [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring and Related Cost, Expected Cost	1,375
Restructuring and Related Cost, Cost Incurred to Date		4,369
Restructuring Charges	(2,994)
Restructuring and Related Cost, Expected Cost Remaining	0
2013 Project [Member] | Water Operating Segment [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring and Related Cost, Expected Cost	3,130
Restructuring and Related Cost, Cost Incurred to Date		1,957
Restructuring Charges	1,173
Restructuring and Related Cost, Expected Cost Remaining	0
2013 Project [Member] | Corporate, Non-Segment [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring and Related Cost, Expected Cost	6,139
Restructuring and Related Cost, Cost Incurred to Date		717
Restructuring Charges	5,422
Restructuring and Related Cost, Expected Cost Remaining	$ 0