Medical Claims Payable (Reconciliation Of Net Incurred Medical Claims To Benefit Expense) (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Reconciliation of net incurred medical claims to benefit expense [Line Items]
Total net incurred medical claims	$ 19,484	$ 16,923	$ 37,823	$ 33,127
Quality improvement and other claims expense	884	805	1,827	1,647
Benefit expense	20,368	17,728	39,650	34,774
Government Business Segment [Member]
Reconciliation of net incurred medical claims to benefit expense [Line Items]
Total net incurred medical claims	12,704	11,039	25,545	21,833
Commercial Specialty Business Segment [Member]
Reconciliation of net incurred medical claims to benefit expense [Line Items]
Total net incurred medical claims	$ 6,780	$ 5,884	$ 12,278	$ 11,294