Rosetta Merger - Narrative (Details) $ / shares in Units, a in Thousands, shares in Millions, $ in Millions			3 Months Ended	6 Months Ended	12 Months Ended
		Jul. 20, 2015 USD ($) a business $ / shares shares	Jun. 30, 2016 USD ($)	Jun. 30, 2016 USD ($)	Dec. 31, 2015 USD ($)
Business Acquisition [Line Items]
Shares exchange in acquisition | shares		41
Pro forma revenue			$ 127	$ 214
Pro forma pre-tax net income			$ 17	$ 14
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					$ 81
Rosetta Merger Expenses					66
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	[1]	$ 2,000
Liquid rich asset based acquired | a		9
Common Stock | Rosetta Resources, Inc [Member]
Business Acquisition [Line Items]
Exchange ratio of common shares for acquired company		0.542

[1] (1) Net of unamortized discount, premium and debt issuance costs and excludes capital lease and other obligations.