Acquisitions Acquisitions Asset (Details) - USD ($) $ in Millions	3 Months Ended		12 Months Ended
	Dec. 31, 2014	Sep. 30, 2014	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Business Acquisition [Line Items]
Payments to Acquire Businesses, Net of Cash Acquired			$ 0	$ 21	$ 74
Oklahoma Resource Basin [Member]
Business Acquisition [Line Items]
Payments to Acquire Businesses, Net of Cash Acquired		$ 68
SCOOP [Member]
Business Acquisition [Line Items]
Payments to Acquire Businesses, Net of Cash Acquired	$ 58