Commitments And Contingencies (Details) $ in Millions	12 Months Ended
	Dec. 31, 2020 USD ($)
Commitments And Contingencies [Line Items]
Gross premium tax rate, state of California	2.35%
Cigna Merger Agreement, termination fee	$ 1,850
Long-term Purchase Commitment, Amount	1,426
Minimum [Member]
Commitments And Contingencies [Line Items]
Estimate of possible loss on loss contingencies	0
Maximum [Member]
Commitments And Contingencies [Line Items]
Estimate of possible loss on loss contingencies	250
BCBS Antitrust Litigation [Member]
Commitments And Contingencies [Line Items]
Estimate of possible loss on loss contingencies	594
Estimated payment obligation, net of third party insurance coverage	548
Anthem, Inc. v. Express Scripts, Inc. [Member]
Commitments And Contingencies [Line Items]
Proceeds originally recevied from divestiture of business	4,675
Anthem, Inc. v. Express Scripts, Inc. [Member] | Pharmacy pricing [Member]
Commitments And Contingencies [Line Items]
Approximate amount of damages sought for operational breaches	14,800
Anthem, Inc. v. Express Scripts, Inc. [Member] | Operational [Member]
Commitments And Contingencies [Line Items]
Approximate amount of damages sought for operational breaches	$ 158