Acquisitions - Fiscal 2019 Acquisitions (Details) $ in Millions		12 Months Ended
	Oct. 01, 2018 USD ($)	Mar. 31, 2019 USD ($) Business	Jun. 30, 2019 USD ($)
Business Acquisition [Line Items]
Goodwill		$ 7,606	$ 8,806
Molina Medicaid Solutions
Business Acquisition [Line Items]
Total consideration transferred	$ 233
Current assets acquired	91
Intangible assets, other than goodwill	112
Other assets	11
Current liabilities	51
Other liabilities	22
Goodwill	$ 92
Weighted average estimated useful life	13 years
Other Acquisitions
Business Acquisition [Line Items]
Total consideration transferred		232
Current assets acquired		74
Intangible assets, other than goodwill		71
Other assets		9
Current liabilities		63
Goodwill		$ 141
Number of companies acquired | Business		7
Contingent consideration		$ 41