ACCOUNTS RECEIVABLE - Components (Details) - USD ($) $ in Millions	Mar. 31, 2020	Dec. 31, 2019
Accounts receivable and allowance for doubtful accounts
Accounts receivable, net	$ 2,722	$ 2,743
Continuing operations:
Accounts receivable and allowance for doubtful accounts
Patient accounts receivable	2,521	2,567
Estimated future recoveries	163	162
Net cost reports and settlements receivable and valuation allowances	37	12
Accounts receivable, net	2,721	2,741
Discontinued operations
Accounts receivable and allowance for doubtful accounts
Accounts receivable, net	$ 1	$ 2