Intangible Assets - Carrying Amount of Goodwill (Details) $ in Thousands	9 Months Ended
Sep. 30, 2019 USD ($)
Goodwill
December 31, 2018	$ 3,320,726
Acquired	70,577
Sold	(5,629)
Measurement period adjustment	(3,018)
September 30, 2019	3,382,656
Critical Illness Recovery Hospital
Goodwill
December 31, 2018	1,045,220
Acquired	30,028
Sold	0
Measurement period adjustment	421
September 30, 2019	1,075,669
Rehabilitation Hospital
Goodwill
December 31, 2018	416,646
Acquired	14,254
Sold	0
Measurement period adjustment	0
September 30, 2019	430,900
Outpatient Rehabilitation
Goodwill
December 31, 2018	642,422
Acquired	7,996
Sold	(5,629)
Measurement period adjustment	0
September 30, 2019	644,789
Concentra
Goodwill
December 31, 2018	1,216,438
Acquired	18,299
Sold	0
Measurement period adjustment	(3,439)
September 30, 2019	$ 1,231,298

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://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 350
-SubTopic 20
-Section 45
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-URI http://asc.fasb.org/extlink&oid=77989000&loc=SL49117168-202975

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
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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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-Publisher FASB
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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

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
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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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- Definition

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

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
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