Loans And Allowance For Credit Losses (Summary Of Information On Impaired Loans) (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016	Dec. 31, 2016
Financing Receivable, Allowance for Credit Losses [Line Items]
Loans and Leases Receivable, Gross, Consumer, Home Equity	$ 2,638		$ 2,645
Unpaid principal balance	790		788
Recorded investment	688		660
Impaired Financing Receivable, Related Allowance	50		63
Average recorded investment	655	$ 619
Interest income recognized	6	9
Owner Occupied [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Unpaid principal balance	126		115
Recorded investment	112		101
Impaired Financing Receivable, Related Allowance	3		3
Average recorded investment	101	122
Interest income recognized	2	2
Municipal [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Unpaid principal balance	1		1
Recorded investment	1		1
Impaired Financing Receivable, Related Allowance	0		0
Average recorded investment	1	1
Interest income recognized	0	0
Commercial Loan [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Unpaid principal balance	587		586
Recorded investment	520		495
Impaired Financing Receivable, Related Allowance	43		55
Average recorded investment	495	405
Interest income recognized	3	4
Commercial Real Estate [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Unpaid principal balance	20		22
Recorded investment	12		13
Impaired Financing Receivable, Related Allowance	0		0
Average recorded investment	13	15
Interest income recognized	0	1
Term [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Unpaid principal balance	98		92
Recorded investment	77		70
Impaired Financing Receivable, Related Allowance	2		2
Average recorded investment	68	106
Interest income recognized	2	3
Commercial Real Estate [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Unpaid principal balance	118		114
Recorded investment	89		83
Impaired Financing Receivable, Related Allowance	2		2
Average recorded investment	81	121
Interest income recognized	2	4
Home Equity Line of Credit [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Unpaid principal balance	23		24
Recorded investment	21		23
Impaired Financing Receivable, Related Allowance	0		0
Average recorded investment	21	25
Interest income recognized	0	0
Consumer Portfolio Segment [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Loans and Leases Receivable, Gross, Consumer, Home Equity	2,638		2,645
Unpaid principal balance	2		2
Recorded investment	1		1
Impaired Financing Receivable, Related Allowance	0		0
Average recorded investment	1	2
Interest income recognized	0	0
One Through Four Family Residential [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Unpaid principal balance	57		59
Recorded investment	54		55
Impaired Financing Receivable, Related Allowance	5		6
Average recorded investment	54	63
Interest income recognized	1	1
Construction And Other Consumer Real Estate [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Unpaid principal balance	3		3
Recorded investment	3		3
Impaired Financing Receivable, Related Allowance	0		0
Average recorded investment	3	3
Interest income recognized	0	0
Revolving Credit Facility [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Average recorded investment	0	0
Interest income recognized	0	0
Consumer Loan [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Unpaid principal balance	85		88
Recorded investment	79		82
Impaired Financing Receivable, Related Allowance	5		6
Average recorded investment	79	93
Interest income recognized	1	1
Impaired Financing Receivable Related Allowance [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Recorded investment	411		401
Impaired Financing Receivable Related Allowance [Member] | Owner Occupied [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Recorded investment	57		30
Impaired Financing Receivable Related Allowance [Member] | Municipal [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Recorded investment	0		0
Impaired Financing Receivable Related Allowance [Member] | Commercial Loan [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Recorded investment	342		341
Impaired Financing Receivable Related Allowance [Member] | Commercial Real Estate [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Recorded investment	10		6
Impaired Financing Receivable Related Allowance [Member] | Term [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Recorded investment	25		17
Impaired Financing Receivable Related Allowance [Member] | Commercial Real Estate [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Recorded investment	35		23
Impaired Financing Receivable Related Allowance [Member] | Home Equity Line of Credit [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Recorded investment	6		7
Impaired Financing Receivable Related Allowance [Member] | Consumer Portfolio Segment [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Recorded investment	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		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		2
Impaired Financing Receivable Related Allowance [Member] | Consumer Loan [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Recorded investment	34		37
Impaired Financing Receivable Recorded Investment With No Allowance [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Recorded investment	277		259
Impaired Financing Receivable Recorded Investment With No Allowance [Member] | Owner Occupied [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Recorded investment	55		71
Impaired Financing Receivable Recorded Investment With No Allowance [Member] | Municipal [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Recorded investment	1		1
Impaired Financing Receivable Recorded Investment With No Allowance [Member] | Commercial Loan [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Recorded investment	178		154
Impaired Financing Receivable Recorded Investment With No Allowance [Member] | Commercial Real Estate [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Recorded investment	2		7
Impaired Financing Receivable Recorded Investment With No Allowance [Member] | Term [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Recorded investment	52		53
Impaired Financing Receivable Recorded Investment With No Allowance [Member] | Commercial Real Estate [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Recorded investment	54		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		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
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	27		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	2		1
Impaired Financing Receivable Recorded Investment With No Allowance [Member] | Consumer Loan [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Recorded investment	45		45
Commercial and Industrial Sector [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Unpaid principal balance	460		470
Recorded investment	407		393
Impaired Financing Receivable, Related Allowance	40		52
Average recorded investment	393	282
Interest income recognized	1	$ 2
Commercial and Industrial Sector [Member] | Impaired Financing Receivable Related Allowance [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Recorded investment	285		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	$ 122		$ 82