Change In Accounting Estimate (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended	6 Months Ended
	Jun. 30, 2016	Jun. 30, 2016
Change in Accounting Estimate [Abstract]
Change in Accounting Estimate Financial Effect on Depreciation Expense, Depreciation Estimate	$ 34	$ 62
Change in Accounting Estimate, Financial Effect on Net Income, Depreciation Adjustment	$ (18)	$ (33)
Change in Accounting Estimate Financial Effect on Net Income Per Share	$ (0.03)	$ (0.05)
Change in Accounting Estimate Financial Effect on Net Income Per Share Diluted	$ (0.03)	$ (0.05)