Income Taxes (Details Textuals) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Income Taxes (Textuals) [Abstract]
Decrease in Unrecognized tax benefits, amounts recorded to equity	$ 289		$ 289
U.S. statutory federal income tax rate			35.00%
Unrecognized tax benefits income tax penalties and interest accrued	$ (41)		$ (41)
Effective tax rate	15.30%	14.30%	7.40%	12.50%
Tax Benefits Recognized in the period			$ 288
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