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Employee Incentive Plans (Share Grants And Fair Value) (Details) - USD ($) $ in Millions	3 Months Ended	12 Months Ended				128 Months Ended	164 Months Ended
	Mar. 31, 2021	Dec. 31, 2020		Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2020
Employee Incentive Plans [Abstract]
Shares granted		1,227,433	[1]	1,374,217	1,146,267	24,497,626
Fair Value - Date of Grant		$ 70		$ 65	$ 62	$ 561	$ 70
Shares Granted IPO to Date							28,245,543
Fair Value - Date of Grant IPO to Date							$ 758
Stock Incentive Plan Granted Shares Adjustment	5,290
[1] Stock Incentive Plan number of granted restricted stock units related to 2020 was adjusted by 5,290 additional restricted stock units during the three months ended March 31, 2021.

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