Segment Reporting - Reconciliation Of Operating Profit Loss (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Segment Reporting [Abstract]
Income (Loss) before Income Taxes	$ (13)	$ (14)	$ (128)	$ (1,471)
Reconciling items:
Amortization of Intangible Assets	60	61	180	184
Restructuring and related costs	20	8	56	50
Interest expense	14	20	46	60
Goodwill, Impairment Loss	0	0	0	1,351
(Gain) loss on divestitures and transaction costs	8	3	14	19
Litigation costs (recoveries), net	0	2	20	15
Other (income) expenses, net	(1)	(8)	0	(8)
Segment Pre-tax Income (Loss)	88	72	188	200
Depreciation and Amortization, excluding Amortization of Acquired Intangible Assets	53	55	166	160
California Medicaid Management Information System (MMIS)	0	0	(7)	0
Other Nonrecurring (Income) Expense	0	0	0	4
Segment Adjusted EBITDA	$ 141	$ 127	$ 347	$ 364