Summary of Significant Accounting Policies and Other Matters - Earnings Per Common Share (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2023	Jun. 30, 2022
Accounting Policies [Abstract]
Net income for common stock	$ 226	$ 255	$ 1,658	$ 857
Weighted average common shares outstanding – basic (shares)	345.9	354.3	349.8	354.2
Add: Incremental shares attributable to effect of potentially dilutive securities (shares)	1.5	1.2	1.5	1.1
Adjusted weighted average common shares outstanding – diluted (shares)	347.4	355.5	351.3	355.3
Net income per common share - basic (dollars per share)	$ 0.65	$ 0.72	$ 4.74	$ 2.42
Net income per common share - diluted (dollars per share)	$ 0.65	$ 0.72	$ 4.72	$ 2.41