Amount, excluding tax collected from customer, of revenue from satisfaction of performance obligation by transferring promised good or service to customer. Tax collected from customer is tax assessed by governmental authority that is both imposed on and concurrent with specific revenue-producing transaction, including, but not limited to, sales, use, value added and excise.

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Basis of Presentation and Significant Events - COVID-19 (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020	Dec. 31, 2020
Adjustments Due to Legislation [Line Items]
Proceeds from Provider Relief Funds	$ 93,300
Government stimulus advance	93,257		$ 93,257
Contract liabilities - deferred revenue	317,962		$ 317,962
Net service revenue	524,835	$ 512,871
Sequestration Payment Adjustment
Adjustments Due to Legislation [Line Items]
Net service revenue	6,400
Suspension of LTACH
Adjustments Due to Legislation [Line Items]
Net service revenue	8,900
Due From Legislation
Adjustments Due to Legislation [Line Items]
Employee-related liabilities	51,800
Due From Legislation \| Other Current Liabilities
Adjustments Due to Legislation [Line Items]
Employee-related liabilities	25,900
Due From Legislation \| Other Noncurrent Liabilities
Adjustments Due to Legislation [Line Items]
Employee-related liabilities	$ 25,900