Lease Commitments - Narrative (Details) - USD ($) $ in Millions	Jun. 30, 2020	Dec. 31, 2019
Lessee, Lease, Description [Line Items]
Operating lease assets	$ 1,129	$ 1,411
Operating lease liabilities	1,160
Finance lease agreement	335
Offshore and onshore drilling rigs
Lessee, Lease, Description [Line Items]
Operating lease assets	47
Compressors
Lessee, Lease, Description [Line Items]
Operating lease assets	133
Storage facilities
Lessee, Lease, Description [Line Items]
Operating lease assets	342
Office space
Lessee, Lease, Description [Line Items]
Operating lease assets	348
Other field equipment
Lessee, Lease, Description [Line Items]
Operating lease assets	$ 71
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	$ 219
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
Oil and gas exploration and development equipment, real estate offices, compressors, and field equipment
Lessee, Lease, Description [Line Items]
Finance lease agreement	$ 335