Fair Value Measurements Recurring Measurements and Additional (Details) - USD ($) $ in Millions		Sep. 30, 2016	Dec. 31, 2015	Sep. 30, 2015
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
Carrying Amount [Member]
Additional disclosure:
Contingent consideration (see Note 2)		81
Other receivables		14	$ 12
Long-term debt, including current portion (1)	[1]	(24,717)	(23,987)
Guarantees		(45)	(29)
Carrying Amount [Member] | Former Venezuela Operations [Member]
Additional disclosure:
Notes Receivable, Fair Value Disclosure		0	0
Fair Value [Member]
Additional disclosure:
Contingent consideration (see Note 2)		81
Other receivables		16	30
Long-term debt, including current portion (1)	[1]	(25,789)	(19,606)
Guarantees		(30)	(16)
Fair Value [Member] | Former Venezuela Operations [Member]
Additional disclosure:
Notes Receivable, Fair Value Disclosure		2	18
Level 1 [Member]
Additional disclosure:
Contingent consideration (see Note 2)		0
Other receivables		14	10
Long-term debt, including current portion (1)	[1]	0	0
Guarantees		0	0
Level 2 [Member]
Additional disclosure:
Contingent consideration (see Note 2)		0
Other receivables		0	2
Long-term debt, including current portion (1)	[1]	(25,789)	(19,606)
Guarantees		(14)	(16)
Level 3 [Member]
Additional disclosure:
Contingent consideration (see Note 2)		81
Other receivables		2	18
Long-term debt, including current portion (1)	[1]	0	0
Guarantees		(16)	0
Fair Value, Measurements, Recurring [Member] | Carrying Amount [Member]
Measured on a recurring basis:
ARO Trust investments		93	67
Fair Value, Measurements, Recurring [Member] | Carrying Amount [Member] | Designated as Hedging Instrument [Member]
Measured on a recurring basis:
Energy derivatives assets		2
Fair Value, Measurements, Recurring [Member] | Carrying Amount [Member] | Not Designated as Hedging Instrument [Member]
Measured on a recurring basis:
Energy derivatives assets		1	5
Energy derivatives liabilities		(7)	(2)
Fair Value, Measurements, Recurring [Member] | Fair Value [Member]
Measured on a recurring basis:
ARO Trust investments		93	67
Fair Value, Measurements, Recurring [Member] | Fair Value [Member] | Designated as Hedging Instrument [Member]
Measured on a recurring basis:
Energy derivatives assets		2
Fair Value, Measurements, Recurring [Member] | Fair Value [Member] | Not Designated as Hedging Instrument [Member]
Measured on a recurring basis:
Energy derivatives assets		1	5
Energy derivatives liabilities		(7)	(2)
Fair Value, Measurements, Recurring [Member] | Level 1 [Member]
Measured on a recurring basis:
ARO Trust investments		93	67
Fair Value, Measurements, Recurring [Member] | Level 1 [Member] | Designated as Hedging Instrument [Member]
Measured on a recurring basis:
Energy derivatives assets		0
Fair Value, Measurements, Recurring [Member] | Level 1 [Member] | Not Designated as Hedging Instrument [Member]
Measured on a recurring basis:
Energy derivatives assets		0	0
Energy derivatives liabilities		(1)	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] | Designated as Hedging Instrument [Member]
Measured on a recurring basis:
Energy derivatives assets		2
Fair Value, Measurements, Recurring [Member] | Level 2 [Member] | Not Designated as Hedging Instrument [Member]
Measured on a recurring basis:
Energy derivatives assets		0	3
Energy derivatives 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] | Designated as Hedging Instrument [Member]
Measured on a recurring basis:
Energy derivatives assets		0
Fair Value, Measurements, Recurring [Member] | Level 3 [Member] | Not Designated as Hedging Instrument [Member]
Measured on a recurring basis:
Energy derivatives assets		1	2
Energy derivatives liabilities		(6)	$ (2)
WilTel Guarantee [Member]
Additional disclosure:
Guarantor Obligations, Maximum Exposure, Undiscounted		$ 32

[1] Excludes capital leases.