Leases Leases - Summary (Details) $ in Millions	Dec. 31, 2019 USD ($)
Leases [Abstract]
Operating Lease, Right-of-Use Asset	$ 525
Finance Lease, Right-of-Use Asset	504
Total Right-of-Use Asset	1,029
Operating Lease, Liability	577
Finance Lease, Liability	519
Total Lease Liabilities	$ 1,096