Recent Accounting Pronouncements Revenue recognition (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017	Jan. 01, 2018
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Cost of Goods and Services Sold	$ 1,323	$ 1,145	$ 2,659	$ 2,266
Selling, General and Administrative Expense	(136)	(117)	(283)	(220)
Other (charges) gains, net	(3)	(2)	(3)	(57)
Operating Income (Loss)	358	218	701	388
Non-operating pension and other postretirement employee benefit (expense) income	$ (26)	(22)	$ (52)	(44)
Scenario, Previously Reported [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Cost of Goods and Services Sold		1,143		2,262
Selling, General and Administrative Expense		(96)		(179)
Other (charges) gains, net		(3)		(58)
Operating Income (Loss)		240		432
Non-operating pension and other postretirement employee benefit (expense) income		0		0
Restatement Adjustment [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Cost of Goods and Services Sold		(2)		(4)
Selling, General and Administrative Expense		21		41
Other (charges) gains, net		(1)		(1)
Operating Income (Loss)		(22)		(44)
Non-operating pension and other postretirement employee benefit (expense) income		$ (22)		$ (44)
Accounting Standards Update 2016-01 [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Cumulative Effect of New Accounting Principle in Period of Adoption					$ 1
Accounting Standards Update 2014-09 [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Cumulative Effect of New Accounting Principle in Period of Adoption					$ 1