Segment Reporting - Reconciliation Of Operating Profit Loss (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Segment Reporting [Abstract]
Income (Loss) before Income Taxes	$ (64)	$ (1,119)	$ (115)	$ (1,457)
Reconciling items:
Amortization of Intangible Assets	60	61	120	123
Restructuring and related costs	29	26	36	42
Interest expense	15	20	32	40
Goodwill, Impairment Loss	0	1,067	0	1,351
(Gain) loss on divestitures and transaction costs	2	2	6	16
Litigation costs (recoveries), net	14	1	20	13
Other (income) expenses, net	(1)	1	1	0
Segment Pre-tax Income (Loss)	55	59	100	128
Depreciation and Amortization, excluding Amortization of Acquired Intangible Assets	55	51	113	105
California Medicaid Management Information System (MMIS)	0	0	(7)	0
Other Nonrecurring (Income) Expense	0	4	0	4
Segment Adjusted EBITDA	$ 110	$ 114	$ 206	$ 237