Basis of Presentation - Net Operating Revenues (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2023	Jun. 30, 2022
Disaggregation of Revenue [Line Items]
Net operating revenues	$ 1,187.1	$ 1,062.5	$ 2,347.5	$ 2,121.8
Medicare
Disaggregation of Revenue [Line Items]
Net operating revenues	763.2	690.7	1,520.7	1,380.8
Medicare Advantage
Disaggregation of Revenue [Line Items]
Net operating revenues	198.1	160.7	384.5	316.7
Managed care
Disaggregation of Revenue [Line Items]
Net operating revenues	133.5	123.3	260.6	254.8
Medicaid
Disaggregation of Revenue [Line Items]
Net operating revenues	48.8	47.5	96.2	89.3
Other third-party payors
Disaggregation of Revenue [Line Items]
Net operating revenues	10.6	9.4	21.5	19.4
Workers’ compensation
Disaggregation of Revenue [Line Items]
Net operating revenues	7.3	5.9	13.0	12.0
Patients
Disaggregation of Revenue [Line Items]
Net operating revenues	4.0	4.1	6.6	9.2
Other income
Disaggregation of Revenue [Line Items]
Net operating revenues	$ 21.6	$ 20.9	$ 44.4	$ 39.6