Income Taxes - Schedule of Significant Components of Deferred Income Tax Assets and Liabilities (Details) - USD ($) $ in Millions	Dec. 31, 2018	Dec. 31, 2017
Assets
Pension Plans	$ 79	$ 41
Other Employee Benefit Plans	146	182
Other	529	657
Total	754	880
Liabilities
Accelerated Depreciation	6,799	6,576
Other	645	722
Total	7,444	7,298
Net Deferred Income Tax Liabilities	$ 6,690	$ 6,418