Lease Commitments - Narrative (Details) - USD ($) $ in Millions	Mar. 31, 2020	Dec. 31, 2019
Lessee, Lease, Description [Line Items]
Operating lease assets	$ 1,193	$ 1,385
Operating lease liabilities	1,221
Finance lease agreement	346
Offshore and onshore drilling rigs
Lessee, Lease, Description [Line Items]
Operating lease assets	105
Compressors
Lessee, Lease, Description [Line Items]
Operating lease assets	154
Other field equipment
Lessee, Lease, Description [Line Items]
Operating lease assets	$ 341
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	$ 619
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	$ 347