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Fair Value Of Financial Instruments (Aggregate Fair Value And Remaining Contractual Principal Balance Outstanding On Fair Value Option) (Detail) - USD ($) $ in Millions | Dec. 31, 2016 | Dec. 31, 2015
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Non Variable Interest Entity [Member] |  |
Schedule Of Fair Value Of Separate Accounts By Major Category Of Investment [Line Items] |  |
Medium-term notes, contractual outstanding principal | $ 158 | $ 217
Medium-term notes, fair value | 101 | 161
Medium-term notes, difference | 57 | 56
Variable Interest Entity [Member] |  |
Schedule Of Fair Value Of Separate Accounts By Major Category Of Investment [Line Items] |  |
Loans receivable, contractual outstanding principal | 1,258 | 1,619
Variable interest entity notes, contractual outstanding principal | 2,449 | 3,663
Loans receivable, fair value | 1,066 | 1,292
Variable interest entity notes, fair value | 1,351 | 2,362
Loans receivable, difference | 192 | 327
Variable interest entity notes, difference | 1,098 | 1,301
Residential Mortgage Loans [Member] | Variable Interest Entity [Member] |  |
Schedule Of Fair Value Of Separate Accounts By Major Category Of Investment [Line Items] |  |
Loans receivable, contractual outstanding principal | 965 | 1,260
Loans receivable, 90 days or more past due, contractual outstanding principal | 143 | 177
Loans receivable, fair value | 894 | 1,149
Loans receivable, 90 days or more past due, fair value | 22 | 36
Loans receivable, difference | 71 | 111
Loans receivable, 90 days or more past due, difference | 121 | 141
Other Loans [Member] | Variable Interest Entity [Member] |  |
Schedule Of Fair Value Of Separate Accounts By Major Category Of Investment [Line Items] |  |
Loans receivable, contractual outstanding principal | 0 | 107
Loans receivable, 90 days or more past due, contractual outstanding principal | 150 | 75
Loans receivable, fair value | 0 | 107
Loans receivable, 90 days or more past due, fair value | 150 | 0
Loans receivable, difference | 0 | 0
Loans receivable, 90 days or more past due, difference | $ 0 | $ 75

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- Definition This item represents the difference between the aggregate fair value and the aggregate unpaid principal balance of loans and long-term receivables (other than securities categorized as trading, available-for-sale or held-to-maturity) that have contractual principal amounts and for which the fair value option has been elected. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 825 -SubTopic 10 -Section 50 -Paragraph 28 -Subparagraph (d)(1) -URI http://asc.fasb.org/extlink&oid=6957238&loc=d3e14064-108612 + Details
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- Definition This item represents the aggregate fair value of loans held as assets that are 90 days or more past due for which the fair value option has been elected. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 825 -SubTopic 10 -Section 50 -Paragraph 28 -Subparagraph (e)(1) -URI http://asc.fasb.org/extlink&oid=6957238&loc=d3e14064-108612 + Details
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- Definition For loans held as assets for which the fair value option has been elected, this item represents the difference between the aggregate fair value and the aggregate unpaid principal balance of those loans that are 90 days or more past due. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 825 -SubTopic 10 -Section 50 -Paragraph 28 -Subparagraph (e)(3) -URI http://asc.fasb.org/extlink&oid=6957238&loc=d3e14064-108612 + Details
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- Definition This item represents the aggregate fair value of loans held as assets that are in nonaccrual status for which the fair value option has been elected, if the entity's policy is to recognize interest income separately from other changes in fair value. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 825 -SubTopic 10 -Section 50 -Paragraph 28 -Subparagraph (e)(2) -URI http://asc.fasb.org/extlink&oid=6957238&loc=d3e14064-108612 + Details
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