Business Acquisitions and Dispositions Business Acquisitions and Dispositions (Details 6 - 2014 Sale to Yield) - USD ($) $ in Millions	Jun. 30, 2015	Jan. 02, 2015	Dec. 31, 2014	Jun. 30, 2014
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Long-term Debt	$ 20,292		$ 20,366
ROFO Assets [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Consideration Paid for Sale of Assets Under Common Control		$ 489		$ 357
Long-term Debt		737		612
Assets Transferred, Carrying Value		405		236
Base Purchase Price [Member] | ROFO Assets [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Consideration Paid for Sale of Assets Under Common Control				349
Working Capital Adjustment [Member] | ROFO Assets [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Consideration Paid for Sale of Assets Under Common Control		$ 9		$ 8