Incentive Plans (Narrative) (Details) - USD ($) shares in Thousands, $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Compensation cost related to unvested restricted performace shares, executive continuity awards and restricted stock attributable to future performance, net of estimated forfeitures	$ 58
Compensation cost related to unvested restricted performace shares, executive continuity awards and restricted stock attributable to future performance, net of estimated forfeitures, weighted-average period (in years)	1 year 4 months 24 days
Maximum Aggregate Number of Shares under ICP	15,400
Restricted performance share plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Weight of return on investment (ROI) on awards	50.00%
Weight of total shareholder return (TSR) on awards	50.00%
Share-based Payment Arrangement [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares available for grant	5,500	7,300	7,700