Goodwill (Details) $ in Millions |
6 Months Ended | |||||
---|---|---|---|---|---|---|
Jun. 30, 2017
USD ($)
| ||||||
Goodwill [Line Items] | ||||||
Goodwill, Beginning Balance | $ 862 | |||||
Goodwill, Acquired During Period | 5 | [1] | ||||
Goodwill, Ending Balance | 867 | |||||
Natural Gas Distribution [Member] | ||||||
Goodwill [Line Items] | ||||||
Goodwill, Beginning Balance | 746 | |||||
Goodwill, Acquired During Period | 0 | [1] | ||||
Goodwill, Ending Balance | 746 | |||||
Energy Services [Member] | ||||||
Goodwill [Line Items] | ||||||
Goodwill, Beginning Balance | 105 | [2] | ||||
Goodwill, Acquired During Period | 5 | [1] | ||||
Goodwill, Ending Balance | 110 | [2] | ||||
Goodwill, Impaired, Accumulated Impairment Loss | 252 | |||||
Corporate and Other [Member] | ||||||
Goodwill [Line Items] | ||||||
Goodwill, Beginning Balance | 11 | |||||
Goodwill, Acquired During Period | 0 | [1] | ||||
Goodwill, Ending Balance | $ 11 | |||||
|