Acquisitions and Disposals - Acquisitions (Details) $ in Millions	9 Months Ended
	Sep. 30, 2023 USD ($) facility	Sep. 30, 2022 USD ($) facility	Dec. 31, 2022 USD ($)
Business Acquisition [Line Items]
Payments for acquisitions, net of cash acquired	$ 48.8	$ 82.6
Goodwill	$ 4,245.1		$ 4,137.1
Equity Method Investments
Business Acquisition [Line Items]
Number of non-controlling interests in surgical facilities acquired | facility	5	7
Number of non-controlling interests in in-development de novo surgical facilities acquired | facility	2	7
Surgical Facility and Physician Practice
Business Acquisition [Line Items]
Payments for acquisitions, net of cash acquired	$ 23.1
Noncash consideration	1.3
Recognized non-controlling interests	20.4
Goodwill	39.7
Surgical Facilities
Business Acquisition [Line Items]
Payments for acquisitions, net of cash acquired	26.9	$ 79.3
Noncash consideration		5.3
Recognized non-controlling interests	55.1	41.5
Goodwill	$ 106.3	$ 121.1
Number of facilities acquired | facility	2	4
Non-controlling interest, fair value	$ 27.3
Net loss on fair value of non-controlling interest	7.1
Surgical Facilities and In-Development De Novo Surgical Facilities
Business Acquisition [Line Items]
Payments for acquisitions, net of cash acquired	50.2	$ 95.1
Surgical Facilities and In-Development De Novo Surgical Facilities | Management rights agreement
Business Acquisition [Line Items]
Intangible assets acquired	$ 21.0
Surgical Hospital
Business Acquisition [Line Items]
Payments for acquisitions, net of cash acquired		64.3
Recognized non-controlling interests		45.3
Goodwill		146.3
Liabilities assumed in acquisition		39.4
Deferred consideration, current		$ 61.0
Surgical Facilities, Existing Markets
Business Acquisition [Line Items]
Number of facilities acquired | facility		2