Equity Method Investments (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Schedule of Equity Method Investments [Line Items]
Income (Loss) from Equity Method Investments, Net of Dividends or Distributions	$ 14	$ (33)	$ 17
Distributions from Equity Method Investments	0	156	0
Equity Method Investments	453	325	437
Equity Method Investment, Financial Statement, Reported Amounts [Abstract]
Retained earnings related to undistributed earnings of equity method investees	106
AMPCO Equity Method Investment, Difference Between Carrying Amount and Underlying Equity [Abstract]
Difference between the carrying value of an equity method investment and the underlying net assets of the investee	8
Balance Sheet Information
Current Assets	343	412
Noncurrent Assets	1,418	1,169
Current Liabilities	229	374
Noncurrent Liabilities	108	33
Statements of Operations Information
Operating Revenues	645	1,142	1,256
Operating Expenses	393	405	388
Operating Income	252	737	868
Other (Income) Net	(9)	(9)	(14)
Income Before Income Taxes	261	746	882
Income Tax Provision	46	172	212
Net Income	$ 215	574	$ 670
AMPCO
Schedule of Equity Method Investments [Line Items]
Ownership interest in equity method investments (in hundredths)	45.00%
Equity Method Investments	$ 120	141
Alba Plant
Schedule of Equity Method Investments [Line Items]
Ownership interest in equity method investments (in hundredths)	28.00%
Equity Method Investments	$ 87	82
CONE Investments
Schedule of Equity Method Investments [Line Items]
Ownership interest in equity method investments (in hundredths)	50.00%
Distribution from Offering Proceeds		204
Income (Loss) from Equity Method Investments, Net of Dividends or Distributions		48
Distributions from Equity Method Investments		156
Equity Method Investments	$ 214	82
CONE Midstream
Schedule of Equity Method Investments [Line Items]
Ownership interest in equity method investments (in hundredths)	32.00%
Other
Schedule of Equity Method Investments [Line Items]
Equity Method Investments	$ 32	$ 20