Other Income and Expense - Other Expense (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Schedule of other expense [Line Items]
Gain (Loss) on Disposition of Assets			$ (14)	$ (12)
Other Expenses	$ 21	$ 12	29	29
Other Expense [Member]
Schedule of other expense [Line Items]
Gain (Loss) on Disposition of Assets	(9)	(7)	(14)	(20)
Water Rights Write-Off	6	0	7	0
Legal settlement	4	5	4	8
Other Cost and Expense, Operating	$ 2	$ 0	$ 4	$ 1