Loans And Allowance For Credit Losses (Summary Of Information On Impaired Loans) (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016	Dec. 31, 2016
Financing Receivable, Allowance for Credit Losses [Line Items]
Loans and Leases Receivable, Gross, Consumer, Home Equity	$ 2,697		$ 2,697		$ 2,645
Unpaid principal balance	655		655		788
Recorded investment	581		581		660
Impaired Financing Receivable, Related Allowance	46		46		63
Average recorded investment	660	$ 743	611	$ 630
Interest income recognized	13	9	18	18
Owner Occupied [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Unpaid principal balance	121		121		115
Recorded investment	105		105		101
Impaired Financing Receivable, Related Allowance	4		4		3
Average recorded investment	109	111	102	113
Interest income recognized	1	3	4	6
Municipal [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Unpaid principal balance	1		1		1
Recorded investment	1		1		1
Impaired Financing Receivable, Related Allowance	0		0		0
Average recorded investment	1	1	1	1
Interest income recognized	0	0	0	0
Commercial Loan [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Unpaid principal balance	497		497		586
Recorded investment	435		435		495
Impaired Financing Receivable, Related Allowance	40		40		55
Average recorded investment	508	542	459	431
Interest income recognized	5	4	8	8
Commercial Real Estate [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Unpaid principal balance	11		11		22
Recorded investment	10		10		13
Impaired Financing Receivable, Related Allowance	0		0		0
Average recorded investment	11	12	11	12
Interest income recognized	0	1	0	1
Term [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Unpaid principal balance	59		59		92
Recorded investment	53		53		70
Impaired Financing Receivable, Related Allowance	1		1		2
Average recorded investment	59	98	60	97
Interest income recognized	7	3	9	7
Commercial Real Estate [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Unpaid principal balance	70		70		114
Recorded investment	63		63		83
Impaired Financing Receivable, Related Allowance	1		1		2
Average recorded investment	70	110	71	109
Interest income recognized	7	4	9	8
Home Equity Line of Credit [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Unpaid principal balance	24		24		24
Recorded investment	22		22		23
Impaired Financing Receivable, Related Allowance	1		1		0
Average recorded investment	21	25	21	24
Interest income recognized	0	0	0	1
Consumer Portfolio Segment [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Loans and Leases Receivable, Gross, Consumer, Home Equity	2,697		2,697		2,645
Unpaid principal balance	1		1		2
Recorded investment	1		1		1
Impaired Financing Receivable, Related Allowance	0		0		0
Average recorded investment	1	2	1	2
Interest income recognized	0	0	0	0
One Through Four Family Residential [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Unpaid principal balance	60		60		59
Recorded investment	58		58		55
Impaired Financing Receivable, Related Allowance	4		4		6
Average recorded investment	58	61	56	61
Interest income recognized	1	1	1	1
Construction And Other Consumer Real Estate [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Unpaid principal balance	3		3		3
Recorded investment	2		2		3
Impaired Financing Receivable, Related Allowance	0		0		0
Average recorded investment	2	3	3	3
Interest income recognized	0	0	0	0
Consumer Loan [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Unpaid principal balance	88		88		88
Recorded investment	83		83		82
Impaired Financing Receivable, Related Allowance	5		5		6
Average recorded investment	82	91	81	90
Interest income recognized	1	1	1	2
Impaired Financing Receivable Related Allowance [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Recorded investment	344		344		401
Impaired Financing Receivable Related Allowance [Member] | Owner Occupied [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Recorded investment	40		40		30
Impaired Financing Receivable Related Allowance [Member] | Municipal [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Recorded investment	0		0		0
Impaired Financing Receivable Related Allowance [Member] | Commercial Loan [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Recorded investment	289		289		341
Impaired Financing Receivable Related Allowance [Member] | Commercial Real Estate [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Recorded investment	5		5		6
Impaired Financing Receivable Related Allowance [Member] | Term [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Recorded investment	15		15		17
Impaired Financing Receivable Related Allowance [Member] | Commercial Real Estate [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Recorded investment	20		20		23
Impaired Financing Receivable Related Allowance [Member] | Home Equity Line of Credit [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Recorded investment	7		7		7
Impaired Financing Receivable Related Allowance [Member] | Consumer Portfolio Segment [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Recorded investment	0		0		0
Impaired Financing Receivable Related Allowance [Member] | One Through Four Family Residential [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Recorded investment	27		27		28
Impaired Financing Receivable Related Allowance [Member] | Construction And Other Consumer Real Estate [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Recorded investment	1		1		2
Impaired Financing Receivable Related Allowance [Member] | Consumer Loan [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Recorded investment	35		35		37
Impaired Financing Receivable Recorded Investment With No Allowance [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Recorded investment	237		237		259
Impaired Financing Receivable Recorded Investment With No Allowance [Member] | Owner Occupied [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Recorded investment	65		65		71
Impaired Financing Receivable Recorded Investment With No Allowance [Member] | Municipal [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Recorded investment	1		1		1
Impaired Financing Receivable Recorded Investment With No Allowance [Member] | Commercial Loan [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Recorded investment	146		146		154
Impaired Financing Receivable Recorded Investment With No Allowance [Member] | Commercial Real Estate [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Recorded investment	5		5		7
Impaired Financing Receivable Recorded Investment With No Allowance [Member] | Term [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Recorded investment	38		38		53
Impaired Financing Receivable Recorded Investment With No Allowance [Member] | Commercial Real Estate [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Recorded investment	43		43		60
Impaired Financing Receivable Recorded Investment With No Allowance [Member] | Home Equity Line of Credit [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Recorded investment	15		15		16
Impaired Financing Receivable Recorded Investment With No Allowance [Member] | Consumer Portfolio Segment [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Recorded investment	1		1		1
Impaired Financing Receivable Recorded Investment With No Allowance [Member] | One Through Four Family Residential [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Recorded investment	31		31		27
Impaired Financing Receivable Recorded Investment With No Allowance [Member] | Construction And Other Consumer Real Estate [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Recorded investment	1		1		1
Impaired Financing Receivable Recorded Investment With No Allowance [Member] | Consumer Loan [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Recorded investment	48		48		45
Commercial and Industrial Sector [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Unpaid principal balance	375		375		470
Recorded investment	329		329		393
Impaired Financing Receivable, Related Allowance	36		36		52
Average recorded investment	398	430	356	317
Interest income recognized	4	$ 1	4	$ 2
Commercial and Industrial Sector [Member] | Impaired Financing Receivable Related Allowance [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Recorded investment	249		249		311
Commercial and Industrial Sector [Member] | Impaired Financing Receivable Recorded Investment With No Allowance [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Recorded investment	$ 80		$ 80		$ 82