CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Comprehensive income:
Net income	$ 727	$ 660	$ 588
Net pension and retiree medical gain arising during the period, net of tax of $—, $— and $—, respectively	(1)	0	0
Pension and retiree medical benefits:
Reclassification of loss to net income, net of tax of $—, $— and $1, respectively	0	0	2
Derivative instruments:
Reclassification of loss to net income, net of tax of $—, $— and $—, respectively	1	2	1
Total other comprehensive income (loss)	0	2	3
Total comprehensive income	$ 727	$ 662	$ 591