Employee Incentive, Retirement, Deferred Compensation, and Career Achievement Plans (Schedule of Changes in Projected Benefit Obligations) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Defined Benefit Plan, Change in Benefit Obligation
Projected benefit obligation at beginning of year	$ 83	$ 56
Benefit cost	17	13
Actuarial (gain)/loss	(8)	14
Projected benefit obligation at the end of year	$ 92	$ 83