Income Taxes (Details Textuals) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Income Taxes Of Non Us Subsidiaries [Line Items]
Benefits related to the realization of certain foreign tax credits	$ 156.0
Decrease in tax rate related to the realization of certain foreign tax credits	2.10%
Income Taxes [Line items]
U.S. statutory federal income tax rate	35.00%	35.00%	35.00%
Income taxes paid	$ 1,400.0	$ 3,000.0	$ 3,400.0
Unrecognized tax benefits	821.4	974.0	870.0	$ 909.0
Unrecognized tax benefits change as a result of potential resolutions of prior years' tax	324.0
Unrecognized tax benefits that affect effective tax rate	723.0	516.0	502.0
Unrecognized tax benefits income tax penalties and interest expense	(90.0)	(9.0)	(38.0)
Unrecognized tax benefits income tax penalties and interest accrued	83.0	173.0
Tax positions related to prior years	(289.0)	$ (81.0)	$ (256.0)
U.S. Tax Act Discrete Net Charge	2,600.0
U.S. Tax Act Deemed Repatriation of Taxes	1,703.0
U.S. Tax Act Deferred Tax on distribution of foreign subs earnings	300.0
U.S. Tax Act Remeasurement Of Deferred Tax Assets and Liabilities	600.0
Additional Tax Deductions pending approval from IRS	2,600.0
Tax Benefits pending approval from IRS	$ 360.0
Tax Year 2018 [Member]
Income Taxes [Line items]
U.S. statutory federal income tax rate	21.00%
Internal Revenue Service (IRS) [Member] | Earliest Year [Member]
Income Tax Contingency [Line Items]
Open tax years by major tax jurisdiction	2008
Internal Revenue Service (IRS) [Member] | Latest Year [Member]
Income Tax Contingency [Line Items]
Open tax years by major tax jurisdiction	2014