Financial Instruments (Details 4) - USD ($) $ in Millions	3 Months Ended	12 Months Ended
Mar. 31, 2016	Dec. 31, 2015
Warrants
Derivative Instruments, Gain (Loss)
Notional amount	$ 0	$ 0
Derivative instruments in fair value and cash flow hedging relationships \| Interest rate swaps
Derivative Instruments, Gain (Loss)
Notional amount	$ 7,300	$ 7,300
Average remaining maturity	7 years	7 years 2 months
Derivative instruments in cash flow hedging relationships \| Interest rate swaps
Derivative Instruments, Gain (Loss)
Notional amount	$ 0	$ 0
Derivative instruments in cash flow hedging relationships \| Interest rate swaps \| Maximum
Derivative Instruments, Gain (Loss)
Net gains (losses) before taxes in other comprehensive income/(loss), cash flow hedges of borrowings	1	1
Gains (losses) expected to be reclassified to net income within the next 12 months	1	1
Derivative instruments in cash flow hedging relationships \| Foreign exchange forward contracts
Derivative Instruments, Gain (Loss)
Notional amount	$ 8,200	$ 8,200
Average remaining maturity	8 months 12 days	8 months 12 days
Net gains (losses) before taxes in other comprehensive income/(loss), cash flow hedges of borrowings	$ (193)	$ 147
Gains (losses) expected to be reclassified to net income within the next 12 months	$ (232)	121
Maximum length of time hedged	4 years
Derivative instruments in cash flow hedging relationships \| Currency swaps
Derivative Instruments, Gain (Loss)
Notional amount	$ 1,400	0
Net gains (losses) before taxes in other comprehensive income/(loss), cash flow hedges of borrowings	(18)	(2)
Gains (losses) expected to be reclassified to net income within the next 12 months	$ 19
Maximum length of time hedged	9 years
Derivative instruments in cash flow hedging relationships \| Currency swaps \| Maximum
Derivative Instruments, Gain (Loss)
Gains (losses) expected to be reclassified to net income within the next 12 months		(1)
Derivative instruments in net investment hedging relationships
Derivative Instruments, Gain (Loss)
Notional amount	$ 6,600	$ 5,500
Average remaining maturity	2 months 12 days	2 months 12 days
Derivative instruments not designated as hedging instruments \| Foreign exchange forward and swap contracts
Derivative Instruments, Gain (Loss)
Notional amount	$ 9,700	$ 11,700
Maximum length of time hedged	1 year
Derivative instruments not designated as hedging instruments \| Equity contracts
Derivative Instruments, Gain (Loss)
Notional amount	$ 1,100	1,200
Derivative instruments not designated as hedging instruments \| Equity contracts \| Maximum
Derivative Instruments, Gain (Loss)
Notional amount	0	100
Derivative instruments not designated as hedging instruments \| Credit default swaps
Derivative Instruments, Gain (Loss)
Notional amount	$ 0	$ 0

Aggregate notional amount specified by the derivative(s). Expressed as an absolute value.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Regulation S-X (SX)
-Number 210
-Article 12
-Section 13
-Sentence Column B

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Amount before tax of increase (decrease) in accumulated equity from transactions and other events and circumstances from non-owner sources, attributable to parent. Excludes net income (loss), and accumulated changes in equity from transactions resulting from investments by owners (distributions to owners).

+ References

No definition available.

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- Definition

The estimated net amount of existing gains or losses on cash flow hedges at the reporting date expected to be reclassified to earnings within the next 12 months.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 30
-Section 50
-Paragraph 1
-Subparagraph (c)
-URI http://asc.fasb.org/extlink&oid=35736893&loc=d3e80748-113994

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- Definition

Average remaining period until maturity of the derivative contract, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

+ References

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- Definition

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+ References

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Maximum length of time over which the entity is hedging its exposure to the variability in future cash flows for forecasted transactions, excluding those forecasted transactions related to the payment of variable interest on existing financial instruments, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 30
-Section 50
-Paragraph 1
-Subparagraph (d)
-URI http://asc.fasb.org/extlink&oid=35736893&loc=d3e80748-113994

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