Commitments and Contingencies (Employee Benefits Narrative) (Details) $ in Millions	12 Months Ended
	Dec. 31, 2020 USD ($) plans	Dec. 31, 2019 USD ($)	Dec. 31, 2018 USD ($)
Commitments and Contingencies Disclosure [Abstract]
Number of defined contribution 401 (k) plans | plans	2
Defined contribution plan, contributions | $	$ 33	$ 37	$ 31