Fair Value Measurements Recurring Measurements and Additional (Details) - USD ($) $ in Millions		Dec. 31, 2015	Dec. 31, 2014
Measured on a recurring basis:
Unamortized debt issuance expense		$ 123	$ 108
Additional disclosure:
Fair Value, Level 1 to level 2 Transfers, Amount		0	0
Fair Value, Level 2 to level 1 Transfers, Amount		0	0
Former Venezuela Operations [Member]
Additional disclosure:
Cash Installments Related To Former Operations Settlement		15
Level 1 [Member]
Additional disclosure:
Notes receivable and other		10	0
Long-term debt, including current portion	[1]	0	0
Guarantee		0	0
Level 2 [Member]
Additional disclosure:
Notes receivable and other		2	4
Long-term debt, including current portion	[1]	(19,606)	(21,131)
Guarantee		(16)	(27)
Level 3 [Member]
Additional disclosure:
Notes receivable and other		18	53
Long-term debt, including current portion	[1]	0	0
Guarantee		0	0
Carrying Amount [Member]
Additional disclosure:
Notes receivable and other		12	30
Long-term debt, including current portion	[1]	(23,987)	(20,779)
Guarantee		(29)	(31)
Carrying Amount [Member] | Former Venezuela Operations [Member]
Additional disclosure:
Notes Receivable, Fair Value Disclosure		0
Fair Value [Member]
Additional disclosure:
Notes receivable and other		30	57
Long-term debt, including current portion	[1]	(19,606)	(21,131)
Guarantee		(16)	(27)
Fair Value [Member] | Former Venezuela Operations [Member]
Additional disclosure:
Notes Receivable, Fair Value Disclosure		18
Fair Value, Measurements, Recurring [Member] | Level 1 [Member]
Measured on a recurring basis:
ARO Trust investments		67	48
Fair Value, Measurements, Recurring [Member] | Level 1 [Member] | Not Designated as Hedging Instrument [Member]
Measured on a recurring basis:
Energy derivatives assets		0	1
Energy derivative liabilities		0	0
Fair Value, Measurements, Recurring [Member] | Level 2 [Member]
Measured on a recurring basis:
ARO Trust investments		0	0
Fair Value, Measurements, Recurring [Member] | Level 2 [Member] | Not Designated as Hedging Instrument [Member]
Measured on a recurring basis:
Energy derivatives assets		3	0
Energy derivative liabilities		0	0
Fair Value, Measurements, Recurring [Member] | Level 3 [Member]
Measured on a recurring basis:
ARO Trust investments		0	0
Fair Value, Measurements, Recurring [Member] | Level 3 [Member] | Not Designated as Hedging Instrument [Member]
Measured on a recurring basis:
Energy derivatives assets		2	2
Energy derivative liabilities		(2)	(2)
Fair Value, Measurements, Recurring [Member] | Carrying Amount [Member]
Measured on a recurring basis:
ARO Trust investments		67	48
Fair Value, Measurements, Recurring [Member] | Carrying Amount [Member] | Not Designated as Hedging Instrument [Member]
Measured on a recurring basis:
Energy derivatives assets		5	3
Energy derivative liabilities		(2)	(2)
Fair Value, Measurements, Recurring [Member] | Fair Value [Member]
Measured on a recurring basis:
ARO Trust investments		67	48
Fair Value, Measurements, Recurring [Member] | Fair Value [Member] | Not Designated as Hedging Instrument [Member]
Measured on a recurring basis:
Energy derivatives assets		5	3
Energy derivative liabilities		$ (2)	$ (2)

[1] Excludes capital leases. The carrying value has been reduced by $123 million and $108 million of debt acquisition costs at December 31, 2015 and 2014, respectively. (See Note 14 – Debt, Banking Arrangements, and Leases.)