SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Summary of Net Revenue (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Revenue from External Customer [Line Items]
Service fee revenue	$ 1,616,630	$ 1,430,061	$ 1,315,077
Imaging center segment revenue
Revenue from External Customer [Line Items]
Service fee revenue	1,604,161	1,425,665	1,313,662
Commercial insurance
Revenue from External Customer [Line Items]
Service fee revenue	897,948	785,128	743,462
Medicare
Revenue from External Customer [Line Items]
Service fee revenue	363,863	311,124	280,911
Medicaid
Revenue from External Customer [Line Items]
Service fee revenue	43,175	38,279	34,731
Workers' compensation/personal injury
Revenue from External Customer [Line Items]
Service fee revenue	47,364	51,339	44,235
Other patient revenue
Revenue from External Customer [Line Items]
Service fee revenue	42,249	31,849	19,398
Management fee revenue
Revenue from External Customer [Line Items]
Service fee revenue	17,936	22,235	19,630
Software and teleradiology
Revenue from External Customer [Line Items]
Service fee revenue	18,082	14,238	10,525
Other
Revenue from External Customer [Line Items]
Service fee revenue	20,111	19,428	12,436
Revenue under capitation arrangements
Revenue from External Customer [Line Items]
Service fee revenue	153,433	152,045	148,334
AI segment revenue
Revenue from External Customer [Line Items]
Service fee revenue	$ 12,469	$ 4,396	$ 1,415