Basis of Presentation and Significant Events (COVID-19) (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019	Dec. 31, 2019
Adjustments Due to Legislation [Line Items]
Net service revenue	$ 487,320	$ 517,842	$ 1,000,191	$ 1,020,427
Proceeds from Provider Relief Funds	88,700
Government stimulus income	44,435	$ 0	44,435	$ 0
Government stimulus advance	44,273		44,273		$ 0
Contract liabilities - deferred revenue	310,712		310,712		$ 0
Sequestration Payment Adjustment and Suspension of LTACH [Member]
Adjustments Due to Legislation [Line Items]
Net service revenue	5,000		2,900
Employee-related liabilities	$ 17,800		$ 17,800