Acquisition and Divestiture - Divestiture of Brazilian Subsidiary (Details) $ in Millions	3 Months Ended	9 Months Ended
	Sep. 30, 2019 USD ($) building	Sep. 30, 2019 USD ($) building	Sep. 30, 2018 USD ($)	Jul. 01, 2019 store
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Number of stores | building	9,900	9,900
Loss on divestiture | $		$ (205)	$ (86)
Retail Long-Term Care Segment
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Number of stores | building	9,900	9,900
Retail Long-Term Care Segment | Brazil Subsidiary | Discontinued Operations, Disposed of by Sale
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Number of stores | store				50
Loss on divestiture | $	$ 205