Condensed Consolidated Statements of Comprehensive Income - USD ($) $ in Millions	3 Months Ended	6 Months Ended
Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Comprehensive Income (Loss), Net of Tax, Including Portion Attributable to Noncontrolling Interest [Abstract]
Net income	$ 502	$ 689	$ 1,124	$ 1,406
Other Comprehensive (Loss) Income, net of tax
Pension and OPEB adjustments	1	1	2	2
Net unrealized gains (losses) on cash flow hedges	1	(6)	13	(4)
Reclassification into earnings from cash flow hedges	(2)	4	(1)	5
Unrealized (losses) gains on available-for-sale securities	(2)	4	(5)	8
Other Comprehensive (Loss) Income, net of tax	(2)	3	9	11
Comprehensive Income	500	692	1,133	1,417
Less: Comprehensive Income Attributable to Noncontrolling Interests	2	3	4	4
Comprehensive Income Attributable to Parent	$ 498	$ 689	$ 1,129	$ 1,413

Amount after tax of increase (decrease) in equity from transactions and other events and circumstances from net income and other comprehensive income, attributable to parent entity. Excludes changes in equity resulting from investments by owners and distributions to owners.

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