CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (UNAUDITED) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2022	Jun. 30, 2021	Jun. 30, 2022	Jun. 30, 2021
Comprehensive income:
Net income	$ 328	$ 311	$ 708	$ 673
Pension and retiree medical benefits:
Reclassifications of loss to net income, net of tax of $—, $—, $1 and $1, respectively	1	1	2	1
Derivative instruments:
Net fair value increase, net of tax of $4, $—, $6 and $—, respectively	11	0	16	0
Other Comprehensive Income (Loss), Cash Flow Hedge, Gain (Loss), Reclassification, before Tax	(1)	(2)	(2)	(5)
Total other comprehensive income	13	3	20	6
Total comprehensive income	$ 341	$ 314	$ 728	$ 679