Premises and Equipment Leases (Details) $ in Millions	Dec. 31, 2017 USD ($)
Operating Leased Assets [Line Items]
Operating Leases, Future Minimum Payments Due, Next Twelve Months	$ 205
Operating Leases, Future Minimum Payments, Due in Two Years	199
Operating Leases, Future Minimum Payments, Due in Three Years	179
Operating Leases, Future Minimum Payments, Due in Four Years	167
Operating Leases, Future Minimum Payments, Due in Five Years	151
Operating Leases, Future Minimum Payments, Due Thereafter	657
Operating Leases, Future Minimum Payments Due	$ 1,558