Contingencies And Commitments (Narrative) (Details)		12 Months Ended
	Jan. 22, 2022 USD ($)	Dec. 31, 2021 USD ($) item	Dec. 31, 2020 USD ($)	Dec. 31, 2019 USD ($)
Loss Contingencies [Line Items]
Loss contingency, estimate		$ 120,000,000
Operating lease ROU asset		147,000,000	$ 182,000,000
Operating lease liability		$ 157,000,000	$ 194,000,000
Weighted average discount rate, operating lease		2.60%	3.20%
Weighted average remaining operating lease term		5 years	6 years
Operating lease expense		$ 49,000,000	$ 50,000,000	$ 54,000,000
Finance lease, net book value		37,000,000	75,000,000
Finance Lease, Liability		175,000,000	234,000,000
Finance Lease, Right-of-Use Asset, Accumulated Amortization		$ 436,000,000	$ 398,000,000
Weighted average discount rate, finance lease		1.40%	2.20%
Weighted average remaining finance lease term		1 year	2 years
Number of leases not yet commenced | item		1
Present value of minimum lease payments		$ 175,000,000	$ 234,000,000
Payables for Congressionally Mandated Assessments		6,000,000	9,000,000
Other Liabilities [Member]
Loss Contingencies [Line Items]
Finance Lease, Liability		375,000,000	216,000,000
Present value of minimum lease payments		$ 375,000,000	$ 216,000,000
Subsequent Event [Member]
Loss Contingencies [Line Items]
Gain (Loss) Related to Litigation Settlement	$ 92,500,000