Intangible Assets - Carrying Amount of Goodwill (Details) $ in Thousands	3 Months Ended
Mar. 31, 2022 USD ($)
Goodwill
Goodwill, Beginning Balance	$ 3,448,912
Acquisition of businesses	3,293
Measurement period adjustment	13,251
Goodwill, Ending Balance	3,465,456
Critical Illness Recovery Hospital
Goodwill
Goodwill, Beginning Balance	1,131,440
Acquisition of businesses	0
Measurement period adjustment	13,251
Goodwill, Ending Balance	1,144,691
Rehabilitation Hospital
Goodwill
Goodwill, Beginning Balance	442,155
Acquisition of businesses	0
Measurement period adjustment	0
Goodwill, Ending Balance	442,155
Outpatient Rehabilitation
Goodwill
Goodwill, Beginning Balance	654,125
Acquisition of businesses	409
Measurement period adjustment	0
Goodwill, Ending Balance	654,534
Concentra
Goodwill
Goodwill, Beginning Balance	1,221,192
Acquisition of businesses	2,884
Measurement period adjustment	0
Goodwill, Ending Balance	$ 1,224,076

Amount after accumulated impairment loss of an asset representing future economic benefits arising from other assets acquired in a business combination that are not individually identified and separately recognized.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
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-Section S99
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-Publisher FASB
-Name Accounting Standards Codification
-Topic 350
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Reference 3: http://www.xbrl.org/2003/role/exampleRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 852
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- Definition

Amount of increase in asset representing future economic benefits arising from other assets acquired in a business combination that are not individually identified and separately recognized resulting from a business combination.

+ References

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- Definition

Amount of increase (decrease) from adjustments after acquisition date under purchase accounting of an asset representing the future economic benefits arising from other assets acquired in a business combination that are not individually identified and separately recognized.

+ References

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- Definition

A roll forward is a reconciliation of a concept from the beginning of a period to the end of a period.

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