REGULATORY ASSETS, LIABILITIES, AND BALANCING ACCOUNTS (Current Regulatory Balancing Accounts, Net) (Details) - USD ($) $ in Millions	Dec. 31, 2019	Dec. 31, 2018
Regulatory Balancing Accounts Payable
Regulatory Liabilities [Line Items]
Total regulatory balancing accounts	$ 1,797	$ 1,076
Regulatory Balancing Accounts Receivable
Regulatory Liabilities [Line Items]
Total regulatory balancing accounts	2,114	1,435
Electric distribution | Regulatory Balancing Accounts Payable
Regulatory Liabilities [Line Items]
Total regulatory balancing accounts	31	0
Electric distribution | Regulatory Balancing Accounts Receivable
Regulatory Liabilities [Line Items]
Total regulatory balancing accounts	0	160
Electric transmission | Regulatory Balancing Accounts Payable
Regulatory Liabilities [Line Items]
Total regulatory balancing accounts	119	134
Electric transmission | Regulatory Balancing Accounts Receivable
Regulatory Liabilities [Line Items]
Total regulatory balancing accounts	9	128
Utility generation | Regulatory Balancing Accounts Receivable
Regulatory Liabilities [Line Items]
Total regulatory balancing accounts	0	79
Gas distribution and transmission | Regulatory Balancing Accounts Payable
Regulatory Liabilities [Line Items]
Total regulatory balancing accounts	45	9
Gas distribution and transmission | Regulatory Balancing Accounts Receivable
Regulatory Liabilities [Line Items]
Total regulatory balancing accounts	363	462
Energy procurement | Regulatory Balancing Accounts Payable
Regulatory Liabilities [Line Items]
Total regulatory balancing accounts	649	59
Energy procurement | Regulatory Balancing Accounts Receivable
Regulatory Liabilities [Line Items]
Total regulatory balancing accounts	901	168
Public purpose programs | Regulatory Balancing Accounts Payable
Regulatory Liabilities [Line Items]
Total regulatory balancing accounts	559	587
Public purpose programs | Regulatory Balancing Accounts Receivable
Regulatory Liabilities [Line Items]
Total regulatory balancing accounts	209	111
Other | Regulatory Balancing Accounts Payable
Regulatory Liabilities [Line Items]
Total regulatory balancing accounts	394	287
Other | Regulatory Balancing Accounts Receivable
Regulatory Liabilities [Line Items]
Total regulatory balancing accounts	$ 632	$ 327