The ratio of Allowance for Credit Losses to All Loans.

No definition available.

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Period Type:	instant

- Definition

Amount of gain (loss) from converting allowance reserve for credit loss to currency of reporting entity from amount denominated or measured in a different currency, which decreases (increases) the allowance for loan and lease losses.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 15
-URI http://asc.fasb.org/extlink&oid=84173941&loc=d3e5212-111524

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-03.7(d))
-URI http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Amount, after recoveries, of loans and leases that have been written-off.

+ References

No definition available.

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

A valuation allowance for financing receivables that are expected to be uncollectible.

+ References

+ Details

Name:	us-gaap_FinancingReceivableAllowanceForCreditLosses
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

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

+ References

+ Details

Name:	us-gaap_FinancingReceivableAllowanceForCreditLossesCollectivelyEvaluatedForImpairment
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Amount of valuation allowance for financing receivables that are expected to be uncollectible that were individually evaluated for impairment.

+ References

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

No definition available.

+ Details

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Period Type:	duration

- Definition

Amount of recovery of financing receivables doubtful of collection that were previously charged off.

+ References

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Amount of direct write-downs of financing receivables charged against the allowance.

+ References

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

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

+ References

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

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

+ References

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Amount before allowance and after deduction of deferred interest and fees, unamortized costs and premiums and discounts from face amounts, of loans and leases held in portfolio, including but not limited to, commercial and consumer loans. Excludes loans and leases covered under loss sharing agreements.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 45
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=82891408&loc=d3e4428-111522

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 4
-URI http://asc.fasb.org/extlink&oid=84173941&loc=d3e5074-111524

+ Details

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Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Amount of expense related loan transactions, lease transactions, credit loss from transactions other than loan and lease transactions, and other loss based on assessment of uncollectability from the counterparty to reduce the account to their net realizable value.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 11B
-Subparagraph (c)(2)
-URI http://asc.fasb.org/extlink&oid=84173941&loc=SL6953423-111524

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 225
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-04.11)
-URI http://asc.fasb.org/extlink&oid=6879574&loc=d3e536633-122882

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 28
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=98514028&loc=d3e3602-108585

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Balance Type:	debit
Period Type:	duration

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- Details

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- Details

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Credit Quality And Allowance For Credit Losses (Changes In The Allowance For Loan Losses And Related Loan Amounts) (Details) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Financing Receivable, Allowance for Credit Losses [Line Items]
Provision for loan losses	$ 17	$ 24	$ 17	$ 16	$ 35	$ 16	$ 49	$ 148	$ 74	$ 248	$ 147
Total loans												$ 49,173	$ 49,088
Financing Receivable [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Balance at beginning of period				730				634	730	634	594
Loan charge-offs									(149)	(214)	(168)
Recoveries on loans previously charged-off									57	68	68
Net loan (charge-offs) recoveries									(92)	(146)	(100)
Provision for loan losses									73	241	142
Foreign currency translation adjustment									1	1	(2)
Balance at end of period	712				730				712	730	634
As a percentage of total loans												1.45%	1.49%	1.29%
Allowance for loan losses individually evaluated for impairment												$ 67	$ 89	$ 53
Allowance for loan losses collectively evaluated for impairment												645	641	581
Total allowance for loan losses	712			730	730			634	730	634	594	712	730	634
Loans individually evaluated for impairment												477	614	424
Loans collectively evaluated for impairment												48,696	48,474	48,660
Total loans												$ 49,173	$ 49,088	$ 49,084
Business loans \| Financing Receivable [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Balance at beginning of period				682				579	682	579	534
Loan charge-offs									(143)	(207)	(157)
Recoveries on loans previously charged-off									50	63	55
Net loan (charge-offs) recoveries									(93)	(144)	(102)
Provision for loan losses									71	246	149
Foreign currency translation adjustment									1	1	(2)
Balance at end of period	661				682				661	682	579
As a percentage of total loans												1.48%	1.53%	1.30%
Allowance for loan losses individually evaluated for impairment												$ 67	$ 86	$ 53
Allowance for loan losses collectively evaluated for impairment												594	596	526
Total allowance for loan losses	661			682	682			579	682	579	534	661	682	579
Loans individually evaluated for impairment												443	566	393
Loans collectively evaluated for impairment												44,188	44,058	44,336
Total loans												44,631	44,624	$ 44,729
Retail loans
Financing Receivable, Allowance for Credit Losses [Line Items]
Total loans												$ 4,542	$ 4,464
Retail loans \| Financing Receivable [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Balance at beginning of period				48				55	48	55	60
Loan charge-offs									(6)	(7)	(11)
Recoveries on loans previously charged-off									7	5	13
Net loan (charge-offs) recoveries									1	(2)	2
Provision for loan losses									2	(5)	(7)
Foreign currency translation adjustment									0	0	0
Balance at end of period	51				48				51	48	55
As a percentage of total loans												1.12%	1.08%	1.26%
Allowance for loan losses individually evaluated for impairment												$ 0	$ 3	$ 0
Allowance for loan losses collectively evaluated for impairment												51	45	55
Total allowance for loan losses	$ 51			$ 48	$ 48			$ 55	$ 48	$ 55	$ 60	51	48	55
Loans individually evaluated for impairment												34	48	31
Loans collectively evaluated for impairment												4,508	4,416	4,324
Total loans												$ 4,542	$ 4,464	$ 4,355