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Fair Value Measurements - Change in Balance Sheet Carrying Value Associated with Level 3 Financial Instruments Carried at Fair Value on Recurring Basis (Detail) - USD ($) $ in Millions | 3 Months Ended
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Mar. 31, 2017 | Mar. 31, 2016
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items] |  |
Balance, beginning of period | $ (1,302) | $ (949)
Total gains/(losses) (realized and unrealized): |  |
Included in earnings | 86 | 367
Included in other comprehensive income | 0 | 0
Settlements | 33 | 18
Transfers in and/or out of level 3 | 0 | 0
Balance, end of period | (1,183) | (564)
Change in unrealized gains/(losses) relating to instruments still held at the reporting date | 57 | 385
Interest Rate Swaps [Member] |  |
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items] |  |
Balance, beginning of period | (46) | (44)
Total gains/(losses) (realized and unrealized): |  |
Included in earnings | 2 | 11
Included in other comprehensive income | 0 | 0
Settlements | 2 | 1
Transfers in and/or out of level 3 | 0 | 0
Balance, end of period | (42) | (32)
Change in unrealized gains/(losses) relating to instruments still held at the reporting date | 4 | 12
Cross-Currency Interest Rate Swaps [Member] |  |
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items] |  |
Balance, beginning of period | (1,243) | (903)
Total gains/(losses) (realized and unrealized): |  |
Included in earnings | 89 | 358
Included in other comprehensive income | 0 | 0
Settlements | 29 | 17
Transfers in and/or out of level 3 | 0 | 0
Balance, end of period | (1,125) | (528)
Change in unrealized gains/(losses) relating to instruments still held at the reporting date | 57 | 375
Other [Member] |  |
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items] |  |
Balance, beginning of period | (13) | (2)
Total gains/(losses) (realized and unrealized): |  |
Included in earnings | (5) | (2)
Included in other comprehensive income | 0 | 0
Settlements | 2 |
Transfers in and/or out of level 3 | 0 | 0
Balance, end of period | (16) | (4)
Change in unrealized gains/(losses) relating to instruments still held at the reporting date | $ (4) | $ (2)

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- Definition Gains losses realized and unrealized. + References No definition available. + Details
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- 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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- Definition Amount of gain (loss) recognized in the income statement of financial instrument classified as a derivative asset (liability) after deduction of derivative liability (asset), measured using unobservable inputs that reflect the entity's own assumption about the assumptions market participants would use in pricing. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 820 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (c)(1) -URI http://asc.fasb.org/extlink&oid=66048111&loc=d3e19207-110258 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 820 -SubTopic 10 -Section 50 -Paragraph 3 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=66048111&loc=d3e19279-110258 + Details
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- Definition Amount of gain (loss) recognized in other comprehensive income (loss) of financial instrument classified as a derivative asset (liability) after deduction of derivative liability (asset), measured using unobservable inputs that reflect the entity's own assumption about the assumptions market participants would use in pricing. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 820 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (c)(1a) -URI http://asc.fasb.org/extlink&oid=66048111&loc=d3e19207-110258 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 820 -SubTopic 10 -Section 50 -Paragraph 3 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=66048111&loc=d3e19279-110258 + Details
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- Definition Amount of settlements of financial instrument classified as a derivative asset (liability) after deduction of derivative liability, measured using unobservable inputs that reflect the entity's own assumption about the assumptions market participants would use in pricing. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 820 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (c)(2) -URI http://asc.fasb.org/extlink&oid=66048111&loc=d3e19207-110258 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 820 -SubTopic 10 -Section 50 -Paragraph 3 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=66048111&loc=d3e19279-110258 + Details
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- Definition Amount of transfers of financial instrument classified as a derivative asset (liability) after deduction of derivative liability (asset) into (out of) level 3 of the fair value hierarchy. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 820 -SubTopic 10 -Section 50 -Paragraph 3 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=66048111&loc=d3e19279-110258 + Details
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