Leases (Unaudited) Future Minimum Lease Payments Under 840 (Details) - USD ($) $ in Millions	3 Months Ended	6 Months Ended
	Jun. 30, 2018	Jun. 30, 2018	Dec. 31, 2018
Future Minimum Lease Payments Under 840 [Abstract]
Operating Leases, Rent Expense	$ 81	$ 173
Operating Leases, Future Minimum Payments Due, Next Twelve Months			$ 312
Operating Leases, Future Minimum Payments, Due in Two Years			270
Operating Leases, Future Minimum Payments, Due in Three Years			221
Operating Leases, Future Minimum Payments, Due in Four Years			186
Operating Leases, Future Minimum Payments, Due in Five Years			152
Operating Leases, Future Minimum Payments, Due Thereafter			939
Operating Leases, Future Minimum Payments Due			$ 2,080