Loans And Allowance For Credit Losses (Summary Of Information On Impaired Loans) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Financing Receivable, Impaired [Line Items]
Impaired Financing Receivable, Average Recorded Investment	$ 238	$ 520
Impaired Financing Receivable, Recorded Investment	261	461
Impaired Financing Receivable, Related Allowance	8	30
Impaired Financing Receivable, Interest Income, Accrual Method	9	27
Impaired Financing Receivable, Unpaid Principal Balance	310	573
Commercial And Industrial [Member]
Financing Receivable, Impaired [Line Items]
Impaired Financing Receivable, Average Recorded Investment	83	289
Impaired Financing Receivable, Recorded Investment	88	222
Impaired Financing Receivable, Related Allowance	4	24
Impaired Financing Receivable, Interest Income, Accrual Method	0	6
Impaired Financing Receivable, Unpaid Principal Balance	112	293
Owner Occupied [Member]
Financing Receivable, Impaired [Line Items]
Impaired Financing Receivable, Average Recorded Investment	47	97
Impaired Financing Receivable, Recorded Investment	60	102
Impaired Financing Receivable, Related Allowance	2	2
Impaired Financing Receivable, Interest Income, Accrual Method	8	6
Impaired Financing Receivable, Unpaid Principal Balance	67	120
Municipal [Member]
Financing Receivable, Impaired [Line Items]
Impaired Financing Receivable, Average Recorded Investment	1	1
Impaired Financing Receivable, Recorded Investment	1	1
Impaired Financing Receivable, Related Allowance	0	0
Impaired Financing Receivable, Interest Income, Accrual Method	0	0
Impaired Financing Receivable, Unpaid Principal Balance	1	1
Commercial Portfolio Segment [Member]
Financing Receivable, Impaired [Line Items]
Impaired Financing Receivable, Average Recorded Investment	131	387
Impaired Financing Receivable, Recorded Investment	149	325
Impaired Financing Receivable, Related Allowance	6	26
Impaired Financing Receivable, Interest Income, Accrual Method	8	12
Impaired Financing Receivable, Unpaid Principal Balance	180	414
Term [Member]
Financing Receivable, Impaired [Line Items]
Impaired Financing Receivable, Average Recorded Investment	41	49
Impaired Financing Receivable, Recorded Investment	40	48
Impaired Financing Receivable, Related Allowance	0	0
Impaired Financing Receivable, Interest Income, Accrual Method	1	12
Impaired Financing Receivable, Unpaid Principal Balance	44	56
Commercial Real Estate Portfolio Segment [Member]
Financing Receivable, Impaired [Line Items]
Impaired Financing Receivable, Average Recorded Investment	42	57
Impaired Financing Receivable, Recorded Investment	40	54
Impaired Financing Receivable, Related Allowance	0	0
Impaired Financing Receivable, Interest Income, Accrual Method	1	12
Impaired Financing Receivable, Unpaid Principal Balance	45	64
Home Equity Line of Credit [Member]
Financing Receivable, Impaired [Line Items]
Impaired Financing Receivable, Average Recorded Investment	13	21
Impaired Financing Receivable, Recorded Investment	14	22
Impaired Financing Receivable, Related Allowance	0	0
Impaired Financing Receivable, Interest Income, Accrual Method	0	1
Impaired Financing Receivable, Unpaid Principal Balance	15	25
One Through Four Family Residential [Member]
Financing Receivable, Impaired [Line Items]
Impaired Financing Receivable, Average Recorded Investment	51	52
Impaired Financing Receivable, Recorded Investment	57	57
Impaired Financing Receivable, Related Allowance	2	4
Impaired Financing Receivable, Interest Income, Accrual Method	0	1
Impaired Financing Receivable, Unpaid Principal Balance	69	67
Construction And Other Consumer Real Estate [Member]
Financing Receivable, Impaired [Line Items]
Impaired Financing Receivable, Average Recorded Investment	1	2
Impaired Financing Receivable, Recorded Investment	1	2
Impaired Financing Receivable, Related Allowance	0	0
Impaired Financing Receivable, Interest Income, Accrual Method	0	0
Impaired Financing Receivable, Unpaid Principal Balance	1	2
Consumer Other Financing Receivable [Member]
Financing Receivable, Impaired [Line Items]
Impaired Financing Receivable, Average Recorded Investment	0	1
Impaired Financing Receivable, Recorded Investment	0	1
Impaired Financing Receivable, Related Allowance	0	0
Impaired Financing Receivable, Interest Income, Accrual Method	0	1
Impaired Financing Receivable, Unpaid Principal Balance	0	1
Commercial Real Estate Construction [Member]
Financing Receivable, Impaired [Line Items]
Impaired Financing Receivable, Average Recorded Investment	1	8
Impaired Financing Receivable, Recorded Investment	0	6
Impaired Financing Receivable, Related Allowance	0	0
Impaired Financing Receivable, Interest Income, Accrual Method	0	0
Impaired Financing Receivable, Unpaid Principal Balance	1	8
Consumer Loan [Member]
Financing Receivable, Impaired [Line Items]
Impaired Financing Receivable, Average Recorded Investment	65	76
Impaired Financing Receivable, Recorded Investment	72	82
Impaired Financing Receivable, Related Allowance	2	4
Impaired Financing Receivable, Interest Income, Accrual Method	0	3
Impaired Financing Receivable, Unpaid Principal Balance	85	95
Impaired Financing Receivable Recorded Investment With an Allowance [Member] [Member]
Financing Receivable, Impaired [Line Items]
Impaired Financing Receivable, Recorded Investment	95	218
Impaired Financing Receivable Recorded Investment With an Allowance [Member] [Member] | Owner Occupied [Member]
Financing Receivable, Impaired [Line Items]
Impaired Financing Receivable, Recorded Investment	29
Impaired Financing Receivable Recorded Investment With an Allowance [Member] [Member] | Municipal [Member]
Financing Receivable, Impaired [Line Items]
Impaired Financing Receivable, Recorded Investment	0
Impaired Financing Receivable Recorded Investment With an Allowance [Member] [Member] | Commercial Portfolio Segment [Member]
Financing Receivable, Impaired [Line Items]
Impaired Financing Receivable, Recorded Investment	65	165
Impaired Financing Receivable Recorded Investment With an Allowance [Member] [Member] | Term [Member]
Financing Receivable, Impaired [Line Items]
Impaired Financing Receivable, Recorded Investment	3
Impaired Financing Receivable Recorded Investment With an Allowance [Member] [Member] | Commercial Real Estate Portfolio Segment [Member]
Financing Receivable, Impaired [Line Items]
Impaired Financing Receivable, Recorded Investment	3	14
Impaired Financing Receivable Recorded Investment With an Allowance [Member] [Member] | Home Equity Line of Credit [Member]
Financing Receivable, Impaired [Line Items]
Impaired Financing Receivable, Recorded Investment	2
Impaired Financing Receivable Recorded Investment With an Allowance [Member] [Member] | One Through Four Family Residential [Member]
Financing Receivable, Impaired [Line Items]
Impaired Financing Receivable, Recorded Investment	25
Impaired Financing Receivable Recorded Investment With an Allowance [Member] [Member] | Construction And Other Consumer Real Estate [Member]
Financing Receivable, Impaired [Line Items]
Impaired Financing Receivable, Recorded Investment	0
Impaired Financing Receivable Recorded Investment With an Allowance [Member] [Member] | Consumer Other Financing Receivable [Member]
Financing Receivable, Impaired [Line Items]
Impaired Financing Receivable, Recorded Investment	0
Impaired Financing Receivable Recorded Investment With an Allowance [Member] [Member] | Commercial Real Estate Construction [Member]
Financing Receivable, Impaired [Line Items]
Impaired Financing Receivable, Recorded Investment	0
Impaired Financing Receivable Recorded Investment With an Allowance [Member] [Member] | Consumer Loan [Member]
Financing Receivable, Impaired [Line Items]
Impaired Financing Receivable, Recorded Investment	27	39
Impaired Financing Receivable Recorded Investment With No Allowance [Member]
Financing Receivable, Impaired [Line Items]
Impaired Financing Receivable, Recorded Investment	166	243
Impaired Financing Receivable Recorded Investment With No Allowance [Member] | Commercial And Industrial [Member]
Financing Receivable, Impaired [Line Items]
Impaired Financing Receivable, Recorded Investment	52	80
Impaired Financing Receivable Recorded Investment With No Allowance [Member] | Owner Occupied [Member]
Financing Receivable, Impaired [Line Items]
Impaired Financing Receivable, Recorded Investment	31	79
Impaired Financing Receivable Recorded Investment With No Allowance [Member] | Municipal [Member]
Financing Receivable, Impaired [Line Items]
Impaired Financing Receivable, Recorded Investment	1	1
Impaired Financing Receivable Recorded Investment With No Allowance [Member] | Commercial Portfolio Segment [Member]
Financing Receivable, Impaired [Line Items]
Impaired Financing Receivable, Recorded Investment	84	160
Impaired Financing Receivable Recorded Investment With No Allowance [Member] | Term [Member]
Financing Receivable, Impaired [Line Items]
Impaired Financing Receivable, Recorded Investment	37	36
Impaired Financing Receivable Recorded Investment With No Allowance [Member] | Commercial Real Estate Portfolio Segment [Member]
Financing Receivable, Impaired [Line Items]
Impaired Financing Receivable, Recorded Investment	37	40
Impaired Financing Receivable Recorded Investment With No Allowance [Member] | Home Equity Line of Credit [Member]
Financing Receivable, Impaired [Line Items]
Impaired Financing Receivable, Recorded Investment	12	13
Impaired Financing Receivable Recorded Investment With No Allowance [Member] | One Through Four Family Residential [Member]
Financing Receivable, Impaired [Line Items]
Impaired Financing Receivable, Recorded Investment	32	28
Impaired Financing Receivable Recorded Investment With No Allowance [Member] | Construction And Other Consumer Real Estate [Member]
Financing Receivable, Impaired [Line Items]
Impaired Financing Receivable, Recorded Investment	1	1
Impaired Financing Receivable Recorded Investment With No Allowance [Member] | Consumer Other Financing Receivable [Member]
Financing Receivable, Impaired [Line Items]
Impaired Financing Receivable, Recorded Investment	0	1
Impaired Financing Receivable Recorded Investment With No Allowance [Member] | Commercial Real Estate Construction [Member]
Financing Receivable, Impaired [Line Items]
Impaired Financing Receivable, Recorded Investment	0	4
Impaired Financing Receivable Recorded Investment With No Allowance [Member] | Consumer Loan [Member]
Financing Receivable, Impaired [Line Items]
Impaired Financing Receivable, Recorded Investment	45	43
Impaired Financing Receivable Related Allowance [Member] | Commercial And Industrial [Member]
Financing Receivable, Impaired [Line Items]
Impaired Financing Receivable, Recorded Investment	$ 36	142
Impaired Financing Receivable Related Allowance [Member] | Owner Occupied [Member]
Financing Receivable, Impaired [Line Items]
Impaired Financing Receivable, Recorded Investment		23
Impaired Financing Receivable Related Allowance [Member] | Municipal [Member]
Financing Receivable, Impaired [Line Items]
Impaired Financing Receivable, Recorded Investment		0
Impaired Financing Receivable Related Allowance [Member] | Term [Member]
Financing Receivable, Impaired [Line Items]
Impaired Financing Receivable, Recorded Investment		12
Impaired Financing Receivable Related Allowance [Member] | Home Equity Line of Credit [Member]
Financing Receivable, Impaired [Line Items]
Impaired Financing Receivable, Recorded Investment		9
Impaired Financing Receivable Related Allowance [Member] | One Through Four Family Residential [Member]
Financing Receivable, Impaired [Line Items]
Impaired Financing Receivable, Recorded Investment		29
Impaired Financing Receivable Related Allowance [Member] | Construction And Other Consumer Real Estate [Member]
Financing Receivable, Impaired [Line Items]
Impaired Financing Receivable, Recorded Investment		1
Impaired Financing Receivable Related Allowance [Member] | Consumer Other Financing Receivable [Member]
Financing Receivable, Impaired [Line Items]
Impaired Financing Receivable, Recorded Investment		0
Impaired Financing Receivable Related Allowance [Member] | Commercial Real Estate Construction [Member]
Financing Receivable, Impaired [Line Items]
Impaired Financing Receivable, Recorded Investment		$ 2