Regulatory Assets, Liabilities, And Balancing Accounts (Current Regulatory Balancing Accounts, Net) (Details) - USD ($) $ in Millions	Jun. 30, 2017	Dec. 31, 2016
Regulatory Balancing Accounts Receivable [Member]
Regulatory Assets [Line Items]
Total regulatory balancing accounts, net	$ 1,565	$ 1,500
Regulatory Balancing Accounts Receivable [Member] | Electric Distribution [Member]
Regulatory Assets [Line Items]
Total regulatory balancing accounts, net	285	132
Regulatory Balancing Accounts Receivable [Member] | Utility Generation [Member]
Regulatory Assets [Line Items]
Total regulatory balancing accounts, net	117	48
Regulatory Balancing Accounts Receivable [Member] | Gas Distribution and Transmission [Member]
Regulatory Assets [Line Items]
Total regulatory balancing accounts, net	433	541
Regulatory Balancing Accounts Receivable [Member] | Energy Procurement [Member]
Regulatory Assets [Line Items]
Total regulatory balancing accounts, net	0	132
Regulatory Balancing Accounts Receivable [Member] | Public Purpose Programs [Member]
Regulatory Assets [Line Items]
Total regulatory balancing accounts, net	129	106
Regulatory Balancing Accounts Receivable [Member] | Other Current Balancing Accounts [Member]
Regulatory Assets [Line Items]
Total regulatory balancing accounts, net	389	297
Regulatory Balancing Accounts Receivable [Member] | Electric Transmission [Member]
Regulatory Assets [Line Items]
Total regulatory balancing accounts, net	212	244
Regulatory Balancing Accounts Payable [Member]
Regulatory Assets [Line Items]
Total regulatory balancing accounts, net	871	645
Regulatory Balancing Accounts Payable [Member] | Gas Distribution and Transmission [Member]
Regulatory Assets [Line Items]
Total regulatory balancing accounts, net	0	48
Regulatory Balancing Accounts Payable [Member] | Energy Procurement [Member]
Regulatory Assets [Line Items]
Total regulatory balancing accounts, net	86	13
Regulatory Balancing Accounts Payable [Member] | Public Purpose Programs [Member]
Regulatory Assets [Line Items]
Total regulatory balancing accounts, net	376	264
Regulatory Balancing Accounts Payable [Member] | Other Current Balancing Accounts [Member]
Regulatory Assets [Line Items]
Total regulatory balancing accounts, net	238	221
Regulatory Balancing Accounts Payable [Member] | Electric Transmission [Member]
Regulatory Assets [Line Items]
Total regulatory balancing accounts, net	$ 171	$ 99