Consolidated Statements of Comprehensive Income (Unaudited) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2024	Jun. 30, 2023	Jun. 30, 2024	Jun. 30, 2023
Statement of Comprehensive Income [Abstract]
Net income attributable to common shareholders	$ 277	$ 280	$ 462	$ 450
Other comprehensive income, net of tax:
Defined benefit pension plan actuarial loss, net of tax of $0 for the three months ended June 30, 2024 and 2023, and $0 for the six months ended June 30, 2024 and 2023	1	0	1	0
Unrealized gain on cash flow hedges, net of tax of $0 for the three months ended June 30, 2024 and 2023, and $3 and $0 for the six months ended June 30, 2024 and 2023, respectively	0	2	19	0
Unrealized (loss) gain on available-for-sale fixed-income securities, net of tax of $0 for the three months ended June 30, 2024 and 2023, and $1 and $0 for the six months ended June 30, 2024 and 2023, respectively	0	(1)	(1)	1
Net other comprehensive income	1	1	19	1
Comprehensive income attributable to common shareholders	$ 278	$ 281	$ 481	$ 451