Equity Method Investments (Details) - USD ($) $ in Millions	3 Months Ended	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Schedule of Equity Method Investments [Line Items]
Distributions from Equity Method Investments		$ 70	$ 0	$ 156
Equity Method Investments	$ 400	400	453	325
Equity Method Investment, Financial Statement, Reported Amounts [Abstract]
Retained earnings related to undistributed earnings of equity method investees		95
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	12	12
Balance Sheet Information
Current Assets	313	313	343
Noncurrent Assets	1,390	1,390	1,418
Current Liabilities	149	149	229
Noncurrent Liabilities	$ 256	256	108
Statements of Operations Information
Operating Revenues		667	645	1,142
Operating Expenses		355	393	405
Operating Income		312	252	737
Other (Income) Net		(7)	(9)	(9)
Income Before Income Taxes		319	261	746
Income Tax Provision		60	46	172
Net Income		$ 259	215	$ 574
AMPCO
Schedule of Equity Method Investments [Line Items]
Ownership interest in equity method investments (in hundredths)	45.00%	45.00%
Equity Method Investments	$ 120	$ 120	120
Alba Plant
Schedule of Equity Method Investments [Line Items]
Ownership interest in equity method investments (in hundredths)	28.00%	28.00%
Equity Method Investments	$ 82	$ 82	87
CONE Investments
Schedule of Equity Method Investments [Line Items]
Ownership interest in equity method investments (in hundredths)	50.00%	50.00%
Distributions from Equity Method Investments	$ 70
Equity Method Investments	$ 172	$ 172	214
CONE Midstream
Schedule of Equity Method Investments [Line Items]
Ownership interest in equity method investments (in hundredths)	34.00%	34.00%
Other
Schedule of Equity Method Investments [Line Items]
Equity Method Investments	$ 26	$ 26	$ 32
Common Units | CONE Midstream
Schedule of Equity Method Investments [Line Items]
Owned (shares)	7,110,638	7,110,638
Subordinated Units | CONE Midstream
Schedule of Equity Method Investments [Line Items]
Owned (shares)	14,581,560	14,581,560