GOODWILL AND OTHER INTANGIBLE ASSETS - Carrying Amount and Accumulated Amortization of Intangible Assets (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2022	Sep. 30, 2021	Dec. 31, 2021
Finite-Lived Intangible Assets [Line Items]
Total gross intangible assets	$ 549,066		$ 549,066		$ 530,955
Total accumulated amortization	(176,513)		(176,513)		(164,935)
Total intangible assets, net	372,553		372,553		366,020
Amortization expense for intangible assets	8,400	$ 7,900	24,600	$ 25,500
Referral sources
Finite-Lived Intangible Assets [Line Items]
Total gross intangible assets	509,646		509,646		482,200
Total accumulated amortization	(160,159)		(160,159)		(137,613)
Trademarks/names
Finite-Lived Intangible Assets [Line Items]
Total gross intangible assets	38,508		38,508		47,718
Total accumulated amortization	(16,254)		(16,254)		(26,936)
Other amortizable intangible assets
Finite-Lived Intangible Assets [Line Items]
Total gross intangible assets	912		912		1,037
Total accumulated amortization	$ (100)		$ (100)		$ (386)