Derivative Instruments - Fair value hedging (Details) - USD ($) $ in Millions	3 Months Ended	6 Months Ended
Jun. 30, 2017	Jun. 30, 2017
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Gains recognized on derivative	$ 3	$ 2
Losses recognized on hedged item	(2)	(1)
Ineffectiveness recognized on fair value hedges	$ 1	$ 1

Amount of gain (loss) from the increase (decrease) in fair value of derivative and nonderivative instruments designated as fair value hedging instruments recognized in the income statement.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 25
-Section 50
-Paragraph 1
-Subparagraph (a)(1)
-URI http://asc.fasb.org/extlink&oid=6886632&loc=d3e76258-113986

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- Definition

Amount of the increase (decrease) in fair value of the hedged item in a fair value hedge recognized in the income statement.

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- References

No definition available.

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- Definition

Amount of gain (loss)recognized in the income statement from the hedging ineffectiveness of a fair value hedge.

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