Employee Benefit Plans (Summary of Changes in the Corporation's Qualified Defined Benefit Pension Plan's Level 3 Investments Measured at Fair Value on a Recurring Basis) (Details) - Private placements - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Balance at beginning of period	$ 39	$ 50
Gains (Losses) Realized	(3)	(3)
Gains (Losses) Unrealized	8	(12)
Purchases	46	38
Sales	(46)	(34)
Balance at end period	$ 44	$ 39