INCOME TAXES - NET OPERATING LOSSES AND TAX CREDIT CARRYFORWARDS (Details) - USD ($) $ in Millions	Dec. 31, 2017	Dec. 31, 2016
Operating Loss Carryforwards [Line Items]
Valuation allowances	$ 133	$ 31
U.S. Federal [Member]
Operating Loss Carryforwards [Line Items]
NOLs	3,145
U.S. Federal [Member] | General business tax credits [Member]
Operating Loss Carryforwards [Line Items]
Tax credits	389
U.S. Federal [Member] | Foreign tax credits [Member]
Operating Loss Carryforwards [Line Items]
Tax credits	631
Valuation allowances	83
U.S. state [Member]
Operating Loss Carryforwards [Line Items]
NOLs	2,295
U.S. state [Member] | General business tax credits [Member]
Operating Loss Carryforwards [Line Items]
Tax credits	51
U.S. state [Member] | Deferred Tax Assets, Operating Loss and Tax Credit Carryforwards [Member]
Operating Loss Carryforwards [Line Items]
Valuation allowances	30	30
Non-U.S. [Member]
Operating Loss Carryforwards [Line Items]
NOLs	607
Non-U.S. [Member] | Deferred Tax Assets, Operating Loss Carryforwards [Member]
Operating Loss Carryforwards [Line Items]
Valuation allowances	20	$ 1
Southern California Gas Company [Member] | U.S. Federal [Member]
Operating Loss Carryforwards [Line Items]
NOLs	334
Southern California Gas Company [Member] | U.S. Federal [Member] | General business tax credits [Member]
Operating Loss Carryforwards [Line Items]
Tax credits	$ 12