ESTIMATES, SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES AND BALANCE SHEET DETAIL Estimates, Significant Accounting Policies and Balance Sheet Detail - Inventory (Details) MMbtu in Millions, $ in Millions		12 Months Ended
		Dec. 31, 2019 USD ($) MMbtu	Dec. 31, 2018 USD ($) MMbtu	Dec. 31, 2017 USD ($)
Inventory Accounting Policies [Abstract]
Energy Related Inventory, Natural Gas in Storage	[1]	$ 39	$ 79
Inventory, Raw Materials and Supplies		22	19
Inventories		$ 61	$ 98
Natural Gas Volumes | MMbtu		19.3	25.9
Interest Costs Capitalized		$ 2	$ 1	$ 3

[1] Natural gas volumes held for operations at December 31, 2019 and 2018 were 19.3 TBtu and 25.9 TBtu, respectively.