Income Taxes (Narrative) (Details) - USD ($) $ in Millions	3 Months Ended		12 Months Ended
	Mar. 31, 2018	Mar. 31, 2017	Dec. 31, 2017
Income Taxes [Abstract]
Tax Cuts and Jobs Act of 2017, Incomplete Accounting, Change in Tax Rate, Deferred Tax Asset, Provisional Income Tax Expense (Benefit)			$ 347
Tax Cuts and Jobs Act of 2017, Incomplete Accounting, Transition Tax for Accumulated Foreign Earnings, Provisional Income Tax Expense (Benefit)			$ 1,100
Reduction of Tax Benefit, Due to Foreign Exchange Losses and Translation Adjustments	$ 37
Statutory U.S. income tax rate	21.00%	35.00%
Foreign Earnings Repatriated	$ 2,000
Income Tax as result of agreement	172
Interest expense, net of tax benefit	$ 12