Restructuring Restructuring Expected Costs, Cost Recognized, and Remaining Costs to be Recognized - 2014 Projects (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
2014 Project [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring and Related Cost, Expected Cost	66,653
Restructuring Charges	55,800
Restructuring and Related Cost, Expected Cost Remaining	10,853
2014 Project [Member] | Electricity Operating Segment [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring and Related Cost, Expected Cost	39,730
Restructuring Charges	29,660
Restructuring and Related Cost, Expected Cost Remaining	10,070
2014 Project [Member] | Gas Operating Segment [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring and Related Cost, Expected Cost	12,455
Restructuring Charges	12,185
Restructuring and Related Cost, Expected Cost Remaining	270
2014 Project [Member] | Water Operating Segment [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring and Related Cost, Expected Cost	1,145
Restructuring Charges	1,106
Restructuring and Related Cost, Expected Cost Remaining	39
2014 Project [Member] | Corporate, Non-Segment [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring and Related Cost, Expected Cost	13,323
Restructuring Charges	12,849
Restructuring and Related Cost, Expected Cost Remaining	474
2014 Project [Member] | Employee severance costs
Restructuring Cost and Reserve [Line Items]
Restructuring and Related Cost, Expected Cost	47,447
Restructuring Charges	47,447
Restructuring and Related Cost, Expected Cost Remaining	0
2014 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	7,952
Restructuring Charges	7,952
Restructuring and Related Cost, Expected Cost Remaining	0
2014 Project [Member] | Other restructuring costs
Restructuring Cost and Reserve [Line Items]
Restructuring and Related Cost, Expected Cost	11,254
Restructuring Charges	401
Restructuring and Related Cost, Expected Cost Remaining	$ 10,853