The valuation allowance for financing receivables that are expected to be uncollectible that were collectively evaluated for impairment.

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The balance of financing receivables that were individually evaluated for impairment.

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Loans And Allowance For Credit Losses (Summary Of ALLL And Outstanding Loan Balances According To The Company's Impairment Method) (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018	Mar. 31, 2019	Dec. 31, 2018	Mar. 31, 2018	Dec. 31, 2017
Financing Receivable, Allowance for Credit Losses [Line Items]
Impaired Financing Receivable, Average Recorded Investment	$ 279	$ 330	$ 265	$ 310
Impaired Financing Receivable, Interest Income, Accrual Method	1	0	2	8
Allowance for loan losses: Individually evaluated for impairment	(14)		(14)			$ (9)
Financing Receivable, Allowance for Credit Losses, Collectively Evaluated for Impairment	489		489			486
Financing Receivable, Individually Evaluated for Impairment	285		285			291
Financing Receivable, Collectively Evaluated for Impairment	48,332		48,332			46,423
Loans and Leases Receivable, Gross	48,617		48,617			46,714
Allowance for loan losses	503	490	503	490	$ 497	495	$ 473	$ 518
Owner Occupied [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Impaired Financing Receivable, Average Recorded Investment	59	54	60	55
Impaired Financing Receivable, Interest Income, Accrual Method	0	0	0	8
Commercial [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Allowance for loan losses: Individually evaluated for impairment	(11)		(11)			(6)
Financing Receivable, Allowance for Credit Losses, Collectively Evaluated for Impairment	327		327			325
Loans and Leases Receivable, Gross	25,107		25,107			24,162
Allowance for loan losses	338	321	338	321	328	331	329	371
Commercial Real Estate Portfolio Segment [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Impaired Financing Receivable, Average Recorded Investment	0	5	0	5
Impaired Financing Receivable, Interest Income, Accrual Method	0	0	0	0
Allowance for loan losses: Individually evaluated for impairment	(1)		(1)
Financing Receivable, Allowance for Credit Losses, Collectively Evaluated for Impairment	113		113
Loans and Leases Receivable, Gross	11,827		11,827
Allowance for loan losses	114	122	114	122	113	110	104	103
Consumer Portfolio Segment [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Impaired Financing Receivable, Average Recorded Investment	0	0	0	0
Impaired Financing Receivable, Interest Income, Accrual Method	0	0	0	0
Allowance for loan losses: Individually evaluated for impairment	(2)		(2)			(2)
Financing Receivable, Allowance for Credit Losses, Collectively Evaluated for Impairment	49		49			52
Loans and Leases Receivable, Gross	11,683		11,683			11,427
Allowance for loan losses	51	47	51	47	$ 56	54	$ 40	$ 44
Commercial Loan [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Impaired Financing Receivable, Average Recorded Investment	168	193	157	182
Impaired Financing Receivable, Interest Income, Accrual Method	1	0	2	8
Term [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Impaired Financing Receivable, Average Recorded Investment	39	58	37	53
Impaired Financing Receivable, Interest Income, Accrual Method	0	0	0	0
Commercial Real Estate [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Impaired Financing Receivable, Average Recorded Investment	39	63	37	58
Impaired Financing Receivable, Interest Income, Accrual Method	0	0	0	0
Allowance for loan losses: Individually evaluated for impairment						(1)
Financing Receivable, Allowance for Credit Losses, Collectively Evaluated for Impairment						109
Loans and Leases Receivable, Gross						11,125
Allowance for loan losses						110
Home Equity Line of Credit [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Impaired Financing Receivable, Average Recorded Investment	14	15	14	14
Impaired Financing Receivable, Interest Income, Accrual Method	0	0	0	0
One Through Four Family Residential [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Impaired Financing Receivable, Average Recorded Investment	55	57	55	55
Impaired Financing Receivable, Interest Income, Accrual Method	0	0	0	0
Construction And Other Consumer Real Estate [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Impaired Financing Receivable, Average Recorded Investment	3	2	2	1
Impaired Financing Receivable, Interest Income, Accrual Method	0	0		0
Consumer Loan [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Impaired Financing Receivable, Average Recorded Investment	72	74	71	70
Impaired Financing Receivable, Interest Income, Accrual Method	0	0	0	0
Municipal [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Impaired Financing Receivable, Average Recorded Investment	1	1	1	1
Impaired Financing Receivable, Interest Income, Accrual Method	0	$ 0	0	$ 0
Outstanding Loan Balances [Member] \| Commercial [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Financing Receivable, Individually Evaluated for Impairment	168		168			164
Financing Receivable, Collectively Evaluated for Impairment	24,939		24,939			23,998
Outstanding Loan Balances [Member] \| Commercial Real Estate Portfolio Segment [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Financing Receivable, Individually Evaluated for Impairment	48		48			55
Financing Receivable, Collectively Evaluated for Impairment	11,779		11,779			11,070
Outstanding Loan Balances [Member] \| Consumer Portfolio Segment [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Financing Receivable, Individually Evaluated for Impairment	69		69			72
Financing Receivable, Collectively Evaluated for Impairment	$ 11,614		$ 11,614			$ 11,355