Fair Value Measurement, Schedule of financial instruments outstanding (Details) - USD ($) $ in Millions	9 Months Ended	12 Months Ended
	Sep. 30, 2015	Dec. 31, 2014
Fair value assets and liabilities measured on a recurring basis [Line Items]
Assets at fair value	$ 1,955	$ 1,649
Liabilities at fair value	61	50
Recurring [Member]
Fair value transfers [Abstract]
Amount of transfers between Level 1 and Level 2 of the fair value hierarchy	0	0
Recurring [Member] | Fair value [Member]
Fair value assets and liabilities measured on a recurring basis [Line Items]
Assets at fair value	1,955	1,649
Liabilities at fair value	61	50
Recurring [Member] | Level 1 [Member]
Fair value assets and liabilities measured on a recurring basis [Line Items]
Assets at fair value	2	2
Liabilities at fair value	35	37
Recurring [Member] | Level 2 [Member]
Fair value assets and liabilities measured on a recurring basis [Line Items]
Assets at fair value	1,953	1,647
Liabilities at fair value	26	13
Recurring [Member] | Level 3 [Member]
Fair value assets and liabilities measured on a recurring basis [Line Items]
Assets at fair value	0	0
Liabilities at fair value	0	0
Recurring [Member] | Derivatives: [Member] | Cross-currency swaps [Member] | Fair value [Member]
Fair value assets and liabilities measured on a recurring basis [Line Items]
Assets at fair value	276	35
Recurring [Member] | Derivatives: [Member] | Cross-currency swaps [Member] | Level 1 [Member]
Fair value assets and liabilities measured on a recurring basis [Line Items]
Assets at fair value	0	0
Recurring [Member] | Derivatives: [Member] | Cross-currency swaps [Member] | Level 2 [Member]
Fair value assets and liabilities measured on a recurring basis [Line Items]
Assets at fair value	276	35
Recurring [Member] | Derivatives: [Member] | Cross-currency swaps [Member] | Level 3 [Member]
Fair value assets and liabilities measured on a recurring basis [Line Items]
Assets at fair value	0	0
Recurring [Member] | Derivatives: [Member] | Basis swaps [Member] | Fair value [Member]
Fair value assets and liabilities measured on a recurring basis [Line Items]
Liabilities at fair value	10
Recurring [Member] | Derivatives: [Member] | Basis swaps [Member] | Level 1 [Member]
Fair value assets and liabilities measured on a recurring basis [Line Items]
Liabilities at fair value	0
Recurring [Member] | Derivatives: [Member] | Basis swaps [Member] | Level 2 [Member]
Fair value assets and liabilities measured on a recurring basis [Line Items]
Liabilities at fair value	10
Recurring [Member] | Derivatives: [Member] | Basis swaps [Member] | Level 3 [Member]
Fair value assets and liabilities measured on a recurring basis [Line Items]
Liabilities at fair value	0
Recurring [Member] | Derivatives: [Member] | Interest rate swaps [Member] | Forward-starting interest rate swaps [Member] | Fair value [Member]
Fair value assets and liabilities measured on a recurring basis [Line Items]
Assets at fair value	5
Liabilities at fair value	8
Recurring [Member] | Derivatives: [Member] | Interest rate swaps [Member] | Forward-starting interest rate swaps [Member] | Level 1 [Member]
Fair value assets and liabilities measured on a recurring basis [Line Items]
Assets at fair value	0
Liabilities at fair value	0
Recurring [Member] | Derivatives: [Member] | Interest rate swaps [Member] | Forward-starting interest rate swaps [Member] | Level 2 [Member]
Fair value assets and liabilities measured on a recurring basis [Line Items]
Assets at fair value	5
Liabilities at fair value	8
Recurring [Member] | Derivatives: [Member] | Interest rate swaps [Member] | Forward-starting interest rate swaps [Member] | Level 3 [Member]
Fair value assets and liabilities measured on a recurring basis [Line Items]
Assets at fair value	0
Liabilities at fair value	0
Recurring [Member] | Derivatives: [Member] | Interest rate swaps [Member] | Fixed-for-floating interest rate swaps [Member] | Fair value [Member]
Fair value assets and liabilities measured on a recurring basis [Line Items]
Assets at fair value	57	16
Recurring [Member] | Derivatives: [Member] | Interest rate swaps [Member] | Fixed-for-floating interest rate swaps [Member] | Level 1 [Member]
Fair value assets and liabilities measured on a recurring basis [Line Items]
Assets at fair value	0	0
Recurring [Member] | Derivatives: [Member] | Interest rate swaps [Member] | Fixed-for-floating interest rate swaps [Member] | Level 2 [Member]
Fair value assets and liabilities measured on a recurring basis [Line Items]
Assets at fair value	57	16
Recurring [Member] | Derivatives: [Member] | Interest rate swaps [Member] | Fixed-for-floating interest rate swaps [Member] | Level 3 [Member]
Fair value assets and liabilities measured on a recurring basis [Line Items]
Assets at fair value	0	0
Recurring [Member] | Derivatives: [Member] | Commodities [Member] | Fair value [Member]
Fair value assets and liabilities measured on a recurring basis [Line Items]
Assets at fair value	4	2
Liabilities at fair value	1	1
Recurring [Member] | Derivatives: [Member] | Commodities [Member] | Level 1 [Member]
Fair value assets and liabilities measured on a recurring basis [Line Items]
Assets at fair value	2	2
Liabilities at fair value	0	1
Recurring [Member] | Derivatives: [Member] | Commodities [Member] | Level 2 [Member]
Fair value assets and liabilities measured on a recurring basis [Line Items]
Assets at fair value	2	0
Liabilities at fair value	1	0
Recurring [Member] | Derivatives: [Member] | Commodities [Member] | Level 3 [Member]
Fair value assets and liabilities measured on a recurring basis [Line Items]
Assets at fair value	0	0
Liabilities at fair value	0	0
Recurring [Member] | Derivatives: [Member] | Embedded derivatives [Member] | Fair value [Member]
Fair value assets and liabilities measured on a recurring basis [Line Items]
Assets at fair value	11	3
Recurring [Member] | Derivatives: [Member] | Embedded derivatives [Member] | Level 1 [Member]
Fair value assets and liabilities measured on a recurring basis [Line Items]
Assets at fair value	0	0
Recurring [Member] | Derivatives: [Member] | Embedded derivatives [Member] | Level 2 [Member]
Fair value assets and liabilities measured on a recurring basis [Line Items]
Assets at fair value	11	3
Recurring [Member] | Derivatives: [Member] | Embedded derivatives [Member] | Level 3 [Member]
Fair value assets and liabilities measured on a recurring basis [Line Items]
Assets at fair value	0	0
Recurring [Member] | Derivatives: [Member] | Foreign currency [Member] | Fair value [Member]
Fair value assets and liabilities measured on a recurring basis [Line Items]
Liabilities at fair value	7	13
Recurring [Member] | Derivatives: [Member] | Foreign currency [Member] | Level 1 [Member]
Fair value assets and liabilities measured on a recurring basis [Line Items]
Liabilities at fair value	0	0
Recurring [Member] | Derivatives: [Member] | Foreign currency [Member] | Level 2 [Member]
Fair value assets and liabilities measured on a recurring basis [Line Items]
Liabilities at fair value	7	13
Recurring [Member] | Derivatives: [Member] | Foreign currency [Member] | Level 3 [Member]
Fair value assets and liabilities measured on a recurring basis [Line Items]
Liabilities at fair value	0	0
Recurring [Member] | Non-derivatives: [Member] | Available-for-sale securities [Member] | Fair value [Member]
Fair value assets and liabilities measured on a recurring basis [Line Items]
Assets at fair value	1,602	1,593
Recurring [Member] | Non-derivatives: [Member] | Available-for-sale securities [Member] | Level 1 [Member]
Fair value assets and liabilities measured on a recurring basis [Line Items]
Assets at fair value	0	0
Recurring [Member] | Non-derivatives: [Member] | Available-for-sale securities [Member] | Level 2 [Member]
Fair value assets and liabilities measured on a recurring basis [Line Items]
Assets at fair value	1,602	1,593
Recurring [Member] | Non-derivatives: [Member] | Available-for-sale securities [Member] | Level 3 [Member]
Fair value assets and liabilities measured on a recurring basis [Line Items]
Assets at fair value	0	0
Recurring [Member] | Non-derivatives: [Member] | Performance share awards [Member] | Fair value [Member]
Fair value assets and liabilities measured on a recurring basis [Line Items]
Liabilities at fair value	35	36
Recurring [Member] | Non-derivatives: [Member] | Performance share awards [Member] | Level 1 [Member]
Fair value assets and liabilities measured on a recurring basis [Line Items]
Liabilities at fair value	35	36
Recurring [Member] | Non-derivatives: [Member] | Performance share awards [Member] | Level 2 [Member]
Fair value assets and liabilities measured on a recurring basis [Line Items]
Liabilities at fair value	0	0
Recurring [Member] | Non-derivatives: [Member] | Performance share awards [Member] | Level 3 [Member]
Fair value assets and liabilities measured on a recurring basis [Line Items]
Liabilities at fair value	$ 0	$ 0