Other Assets (Details 3) $ in Millions	Dec. 31, 2017 USD ($)
Estimated amortization expense for other intangible assets
Estimated amortization expense, 2018	$ 221
Estimated amortization expense, 2019	183
Estimated amortization expense, 2020	156
Estimated amortization expense, 2021	126
Estimated amortization expense, 2022	$ 98