Organization and Basis of Presentation (Details) member in Thousands, $ in Millions		1 Months Ended	6 Months Ended	12 Months Ended
	Dec. 31, 2019 USD ($) member state	Oct. 31, 2019	Jun. 30, 2020 USD ($) member county	Dec. 31, 2019 USD ($) member segment state	Dec. 31, 2018 USD ($)	Dec. 31, 2017 USD ($)
Basis Of Presentation [Line Items]
Number of reportable segments | segment				2
Premium revenue				$ 16,208	$ 17,612	$ 18,854
Texas
Basis Of Presentation [Line Items]
Number of members served, approximately (in member) | member	97			97
Premium revenue				$ 2,062
Texas Health and Human Services Commission, STARPLUS Program
Basis Of Presentation [Line Items]
Contract term		3 years
Health Plans
Basis Of Presentation [Line Items]
Number of states in which company operates (in state) | state	14			14
Number of members eligible for the health care programs | member	3,300			3,300
Minimum contract terms				3 years
Maximum contract term				5 years
Premium revenue				$ 16,208	17,612	18,854
Health Plans | Texas
Basis Of Presentation [Line Items]
Premium revenue				2,991	3,244	2,813
Health Plans | Illinois
Basis Of Presentation [Line Items]
Premium revenue				$ 1,002	$ 793	$ 593
Health Plans | STAR/CHIP Contracts | Texas
Basis Of Presentation [Line Items]
Number of members served, approximately (in member) | member	114			114
Premium revenue				$ 315
NextLevel Health Partners, Inc. | Illinois
Basis Of Presentation [Line Items]
Number of members served, approximately (in member) | member	50			50
Purchase price of assets	$ 50
YourCare Health Plan | Forecast | New York
Basis Of Presentation [Line Items]
Number of members served, approximately (in member) | member			46
Purchase price of assets			$ 40
Number of countries | county			7