Summary Of Significant Accounting Policies New Accounting Pronouncements (Narrative) (Details) - Adjustments for New Accounting Pronouncement [Member] $ in Billions	12 Months Ended
	Dec. 31, 2019 USD ($)
Loans Receivable and related Allowance for Credit Losses [Member]
Item Effected [Line Items]
New Accounting Pronouncement or Change in Accounting Principle, Effect of Adoption, Quantification	$ 2.5
Allowance for Credit Losses [Member]
Item Effected [Line Items]
Write Off Policy Cap Percentage Based On Future Cash Flows	200.00%
Minimum [Member] | Annual Net Income Impact [Member]
Item Effected [Line Items]
New Accounting Pronouncement Estimated Impact	30.00%
Minimum [Member] | Quarterly Net Income Impact [Member]
Item Effected [Line Items]
New Accounting Pronouncement Estimated Impact	50.00%
Minimum [Member] | Allowance for Credit Losses [Member]
Item Effected [Line Items]
New Accounting Pronouncement Estimated Impact	12.00%
Maximum [Member] | Annual Net Income Impact [Member]
Item Effected [Line Items]
New Accounting Pronouncement Estimated Impact	60.00%
Maximum [Member] | Quarterly Net Income Impact [Member]
Item Effected [Line Items]
New Accounting Pronouncement Estimated Impact	80.00%
Maximum [Member] | Allowance for Credit Losses [Member]
Item Effected [Line Items]
New Accounting Pronouncement Estimated Impact	15.00%