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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, 2018 | Dec. 31, 2017
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Variable Interest Entity [Member] |  |
Schedule Of Fair Value Of Separate Accounts By Major Category Of Investment [Line Items] |  |
Loans receivable, contractual outstanding principal | $ 555 | $ 2,296
Loans receivable, fair value | 428 | 1,679
Loans receivable, difference | 127 | 617
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 | 390 | 732
Loans receivable, 90 days or more past due, contractual outstanding principal | 165 | 170
Loans receivable, fair value | 389 | 727
Loans receivable, 90 days or more past due, fair value | 39 | 32
Loans receivable, difference | 1 | 5
Loans receivable, 90 days or more past due, difference | 126 | 138
Corporate Loans [Member] | Variable Interest Entity [Member] |  |
Schedule Of Fair Value Of Separate Accounts By Major Category Of Investment [Line Items] |  |
Loans receivable, 90 days or more past due, contractual outstanding principal | 0 | 1,394
Loans receivable, 90 days or more past due, fair value | 0 | 920
Loans receivable, 90 days or more past due, difference | 0 | 474
Medium Term Notes [Member] | Non Variable Interest Entity [Member] |  |
Schedule Of Fair Value Of Separate Accounts By Major Category Of Investment [Line Items] |  |
Long-term debt instruments, contractual outstanding principal | 139 | 180
Long-term debt instruments, fair value | 123 | 115
Long-term debt instruments, difference | 16 | 65
Variable Interest Entity Notes [Member] | Variable Interest Entity [Member] |  |
Schedule Of Fair Value Of Separate Accounts By Major Category Of Investment [Line Items] |  |
Long-term debt instruments, contractual outstanding principal | 1,525 | 1,882
Long-term debt instruments, fair value | 709 | 1,069
Long-term debt instruments, difference | $ 816 | $ 813

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- Definition Fair Value Option Aggregate Fair Value Long Term Debt Instruments + References No definition available. + Details
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- Definition Fair Value Option Contractual Outstanding Principal Loans Receivable + References No definition available. + Details
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- Definition Fair Value Option Contractual Outstanding Principal Long-Term Debt Instruments + References No definition available. + Details
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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=75031198&loc=d3e14064-108612 + Details
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- Definition This item represents the difference between the aggregate fair value and the aggregate unpaid principal balance of long-term debt instruments 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)(2) -URI http://asc.fasb.org/extlink&oid=75031198&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=75031198&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=75031198&loc=d3e14064-108612 + Details
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