Income Taxes (Unaudited) (Details 1) - USD ($) $ in Millions	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017	Dec. 31, 2017
Income Tax Disclosure [Abstract]
Federal and foreign income tax expense	$ 93	$ 139	$ 385	$ 534
Effective income tax rate	7.50%	17.80%	13.00%	22.40%
Effective Income Tax Rate Reconciliation, at Federal Statutory Income Tax Rate, Percent			21.00%		35.00%
Effective Income Tax Rate Reconciliation, Other Adjustments, Amount	$ 70	$ 62
Effective Income Tax Rate Reconciliation, Deduction, Amount	35
Effective Income Tax Rate Reconciliation, Nondeductible Expense, Other, Amount	$ 20
Effective Income Tax Rate Reconciliation, Deduction, Qualified Production Activity, Amount		$ 27		$ 57
Effective Income Tax Rate Reconciliation, Share-based Compensation, Excess Tax Benefit, Amount			$ 26	47
Effective Income Tax Rate Reconciliation, Tax Settlement, Amount				$ 42