Leases (Components of Lease Expense) (Details) $ in Millions	12 Months Ended
	Dec. 31, 2019 USD ($)
Lessee, Lease, Description [Line Items]
Operating lease expense	$ 15,854
Short-term lease expense	72,562	[1]
Lease expense, gross	88,416
Less: Sublease income	1,077
Total lease expense	$ 87,339
Minimum [Member]
Lessee, Lease, Description [Line Items]
Short term lease, lease term	1 month
Maximum [Member]
Lessee, Lease, Description [Line Items]
Short term lease, lease term	1 year

[1] Short-term lease expense includes all leases with lease terms ranging from less than one month to one year. Short-term leases include, among other things, construction equipment rented on an as-needed basis as well as temporary housing.