Supplemental Information Related Operating Leases (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Leases [Abstract]
Operating Lease, Payments	$ 164	$ 163
Right-of-Use Asset Obtained in Exchange for Operating Lease Liability	198	504
Other non-cash modifications to lease assets	$ 98	$ 31