Income Taxes (Federal Statutory Tax Rate and Income Tax Expense) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Effective Income Tax Rate Reconciliation, Amount [Abstract]
Income tax expense (benefit) at statutory rate	$ 295	$ 321	$ (406)
Tax on non-U.S. earnings	(25)	(46)	(27)
State income taxes, net of federal benefit	26	24	(30)
Recognition of previously unrecognized income tax benefits	(13)	1	(29)
Other provisions	(2)	14	9
Valuation allowances	(7)	(9)	55
Section 199 deduction	(15)	(19)	(12)
Tax on undistributed non-U.S. earnings	25	(7)	(19)
Research credits	(2)	(5)	(6)
Total income tax expense (benefit)	$ 282	$ 274	$ (465)
Effective Income Tax Rate Reconciliation, Percent [Abstract]
Income tax expense (benefit) at statutory rate	35.00%	35.00%	35.00%
Tax on non-U.S. earnings	(3.00%)	(5.00%)	2.30%
State income taxes, net of federal benefit	3.10%	2.60%	2.60%
Recognition of previously unrecognized income tax benefits	(1.60%)	0.10%	2.50%
Other provisions	(0.40%)	1.60%	(0.70%)
Valuation allowances	(0.80%)	(1.00%)	(4.70%)
Section 199 deduction	(1.70%)	(2.10%)	1.00%
Tax on undistributed non-U.S. earnings	3.00%	(0.80%)	1.60%
Research credits	(0.20%)	(0.50%)	0.50%
Total income tax expense (benefit), percent	33.40%	29.90%	40.10%