Investments - Schedule of Investments Table (Details) (USD $) In Millions, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012
Schedule of Equity Method Investments [Line Items]
Investments	$ 477	$ 728
FTS International, Inc.
Schedule of Equity Method Investments [Line Items]
Equity Method Investment, Ownership Percentage	30.00%	30.00%
Equity Method Investments	138	298
Chaparral Energy, Inc.
Schedule of Equity Method Investments [Line Items]
Equity Method Investment, Ownership Percentage	20.00%	20.00%
Equity Method Investments	143	141
Sundrop Fuels, Inc.
Schedule of Equity Method Investments [Line Items]
Equity Method Investment, Ownership Percentage	56.00%	50.00%
Equity Method Investments	135	111
Clean Energy Fuels Corp.
Schedule of Equity Method Investments [Line Items]
Cost method percentage approximate owned	0.00%	0.00%
Fair Value Method Investment Ownership Percentage	0.00%	1.00%
Cost Method Investments	0	100
Fair Value Method Investments	0	12
Gastar Exploration Ltd.
Schedule of Equity Method Investments [Line Items]
Fair Value Method Investment Ownership Percentage	0.00%	10.00%
Fair Value Method Investments	0	8
Other Investment Companies [Member]
Schedule of Equity Method Investments [Line Items]
Equity Method Investment, Ownership Percentage	0.00%	0.00%
Cost Method Investments	$ 61	$ 58