Rosetta Merger - Narrative (Details) $ / shares in Units, a in Thousands, shares in Millions, $ in Millions			2 Months Ended	3 Months Ended		9 Months Ended
		Jul. 20, 2015 USD ($) a business $ / shares shares	Sep. 30, 2015 USD ($)	Sep. 30, 2015 USD ($)	Sep. 30, 2014 USD ($)	Sep. 30, 2015 USD ($)	Sep. 30, 2014 USD ($)
Business Acquisition [Line Items]
Shares exchange in acquisition | shares		41
Rosetta Merger Expenses	[1]			$ 71	$ 0	$ 73	$ 0
Pro forma revenue			$ 81
Pro forma pre-tax net income			$ 43
Rosetta Resources, Inc [Member]
Business Acquisition [Line Items]
Shares exchange in acquisition | shares		41
Number of onshore plays added in acquisition | business		2
Merger related costs including noncash share-based compensation expense				71		73
Rosetta Merger Expenses						58
Merger related costs related to noncash share-based compensation						15
Share price | $ / shares		$ 36.97
Eagle Ford Shale [Member] | Rosetta Resources, Inc [Member]
Business Acquisition [Line Items]
Liquid rich asset based acquired | a		50
Permian [Member] | Rosetta Resources, Inc [Member]
Business Acquisition [Line Items]
Liquid rich asset based acquired | a		54
Delaware Basin [Member] | Rosetta Resources, Inc [Member]
Business Acquisition [Line Items]
Liquid rich asset based acquired | a		45
Midland Basin [Member] | Rosetta Resources, Inc [Member]
Business Acquisition [Line Items]
Long-term Debt, Fair Value	[2]	$ 2,000
Liquid rich asset based acquired | a		9
Common Stock | Rosetta Resources, Inc [Member]
Business Acquisition [Line Items]
Shares exchange in acquisition | shares		41
Exchange ratio of common shares for acquired company		0.542
Rosetta Resources, Inc [Member] | Rosetta Resources, Inc [Member]
Business Acquisition [Line Items]
Merger related costs including noncash share-based compensation expense				$ 32		$ 37

[1] Amount represents expenses associated with the completion of the Rosetta Merger. See Note 3. Rosetta Merger

[2] Excludes capital lease obligations.