Basis of Presentation and Significant Accounting Policies (Narrative) (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018	Jan. 01, 2019	Dec. 31, 2018
Net Operating Revenues, Policy [Abstract]
Value of charity care services at the Company's standard charges included in contractual allowances	$ 141.0	$ 114.0
Estimated cost incurred by Company to provide charity care services	15.0	14.0
Patient accounts receivable, net of allowance for doubtful accounts	2,360.0			$ 2,352.0
Third-Party Reimbursement [Abstract]
Amounts due to third party payors	148.0			144.0
Amounts due from third party payors	142.0			$ 155.0
Accounting for the Impairment or Disposal of Long-Lived Assets
Impairment and (gain) loss on sale of businesses, net	38.0	28.0
Goodwill allocated to hospital disposal group held for sale	8.0	$ 25.0
New Accounting Pronouncements, Policy [Abstract]
Operating lease right-of-use asset	623.0
Operating lease liability	$ 638.0
ASU 2016-02 [Member]
New Accounting Pronouncements, Policy [Abstract]
Operating lease right-of-use asset			$ 673.0
Operating lease liability			$ 673.0