Segment Information Major Customers (Details)	3 Months Ended	9 Months Ended
Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Revenue, Major Customer [Line Items]
Segment Reporting, Disclosure of Major Customers	For the three months ended September 30, 2016, no single customer represented more than 10% of total Company, or the Gas, or Water operating segment revenues.	For the three months ended September 30, 2015, no single customer represented more than 10% of total Company, or the Gas, or Water operating segment revenues.	For the nine months ended September 30, 2016, no single customer represented more than 10% of total Company, or the Gas, or Water operating segment revenues.	For the nine months ended September 30, 2015, no single customer represented more than 10% of total Company, or the Electricity, Gas, or Water operating segment revenues.
Revenue [Member] \| Threshold for Reporting Customer Concentration [Member]
Revenue, Major Customer [Line Items]
Concentration Risk, Percentage	10.00%	10.00%	10.00%	10.00%
Revenue [Member] \| Threshold for Reporting Customer Concentration [Member] \| Electricity Operating Segment [Member]
Revenue, Major Customer [Line Items]
Concentration Risk, Percentage	14.00%	11.00%	12.00%

Segment Reporting, Disclosure of Major Customers

For the three months ended September 30, 2016, no single customer represented more than 10% of total Company, or the Gas, or Water operating segment revenues.

For the three months ended September 30, 2015, no single customer represented more than 10% of total Company, or the Gas, or Water operating segment revenues.

For the nine months ended September 30, 2016, no single customer represented more than 10% of total Company, or the Gas, or Water operating segment revenues.

For the nine months ended September 30, 2015, no single customer represented more than 10% of total Company, or the Electricity, Gas, or Water operating segment revenues.

Revenue, Major Customer [Line Items]

Concentration Risk, Percentage

14.00%

11.00%

12.00%