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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 | Sep. 30, 2015 | Dec. 31, 2014
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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 | $ 223 | $ 242
Medium-term notes, fair value | 170 | 197
Medium-term notes, difference | 53 | 45
Variable Interest Entity [Member] |  |
Schedule Of Fair Value Of Separate Accounts By Major Category Of Investment [Line Items] |  |
Loans receivable, contractual outstanding principal | 1,705 | 2,502
Variable interest entity notes, contractual outstanding principal | 3,758 | 3,584
Loans receivable, fair value | 1,351 | 2,142
Variable interest entity notes, fair value | 2,460 | 2,479
Loans receivable, difference | 354 | 360
Variable interest entity notes, difference | 1,298 | 1,105
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 | 1,331 | 1,554
Loans receivable, 90 days or more past due, contractual outstanding principal | 194 | 227
Loans receivable, fair value | 1,233 | 1,377
Loans receivable, 90 days or more past due, fair value | 11 | 54
Loans receivable, difference | 98 | 177
Loans receivable, 90 days or more past due, difference | 183 | 173
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 | 107 | 721
Loans receivable, 90 days or more past due, contractual outstanding principal | 73 |
Loans receivable, fair value | 107 | 711
Loans receivable, difference | 0 | $ 10
Loans receivable, 90 days or more past due, difference | $ 73 |

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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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