Lease Commitments - Narrative (Details) - USD ($) $ in Millions	Sep. 30, 2020	Dec. 31, 2019
Lessee, Lease, Description [Line Items]
Operating lease assets	$ 1,196	$ 1,411
Finance lease agreement	325
Offshore and onshore drilling rigs
Lessee, Lease, Description [Line Items]
Operating lease assets	56
Compressors
Lessee, Lease, Description [Line Items]
Operating lease assets	155
Storage facilities
Lessee, Lease, Description [Line Items]
Operating lease assets	297
Office space
Lessee, Lease, Description [Line Items]
Operating lease assets	417
Other field equipment
Lessee, Lease, Description [Line Items]
Operating lease assets	$ 58
Oil and gas exploration and development equipment | Minimum
Lessee, Lease, Description [Line Items]
Contract expiration term	2 years
Oil and gas exploration and development equipment | Maximum
Lessee, Lease, Description [Line Items]
Contract expiration term	8 years
Pipelines, rail cars, storage facilities, easements and real estate
Lessee, Lease, Description [Line Items]
Operating lease assets	$ 262
Real estate leases | Minimum
Lessee, Lease, Description [Line Items]
Contract expiration term	1 year
Real estate leases | Maximum
Lessee, Lease, Description [Line Items]
Contract expiration term	13 years