SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Details - Narrative)								1 Months Ended			12 Months Ended			24 Months Ended		40 Months Ended
	Nov. 05, 2019 USD ($)	Aug. 01, 2019 USD ($)	Jan. 01, 2019 USD ($)	Apr. 12, 2018 USD ($)	Mar. 01, 2018 USD ($)	Feb. 01, 2018 USD ($) shares	Mar. 24, 2017 USD ($)	Aug. 31, 2020 USD ($)	Sep. 30, 2019 USD ($)	Nov. 06, 2014 USD ($)	Dec. 31, 2021 USD ($) jointVenture	Dec. 31, 2020 USD ($)	Dec. 31, 2019 USD ($)	Oct. 31, 2025 USD ($)	Dec. 31, 2021 USD ($) jointVenture	Oct. 31, 2023 USD ($)	Apr. 15, 2021 shares	Nov. 01, 2020	Jul. 01, 2020 USD ($)	Oct. 11, 2019 shares	Jun. 30, 2019 USD ($) agreement	Apr. 01, 2017	Dec. 31, 2016 USD ($)	Oct. 06, 2014	Nov. 30, 2006 USD ($)
Property, Plant and Equipment [Line Items]
Factoring receivable											$ 17,700,000	$ 20,500,000			$ 17,700,000
Service fee revenue											1,315,077,000	1,071,840,000	$ 1,154,179,000
Deferred financing costs, net of accumulated amortization											2,100,000	1,800,000			2,100,000
Goodwill											513,820,000	472,879,000	441,973,000		513,820,000
Indefinite lived intangible assets											7,100,000	7,100,000			7,100,000
Lease abandonment charges											12,600,000
Workers' compensation liability, current											3,500,000	4,100,000			3,500,000
Medical malpractice deductible per incidence											$ 10,000	10,000			10,000
Employer matching contribution, percent											1.00%
Employee contribution, percent											4.00%
Expected employee contribution											$ 3,000,000	0
Contract loss accrual													4,600,000
Contract loss accrual, written off													558,000
Accumulated other comprehensive income											228,904,000	165,743,000			228,904,000
Total net assets											$ 75,489,000	61,644,000			$ 75,489,000
Number of unconsolidated joint ventures | jointVenture											13				13
Payments to acquire additional interest in subsidiaries											$ 1,441,000	1,635,000	103,000
Management service fees											19,600,000	11,300,000	11,400,000
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2022-01-01
Property, Plant and Equipment [Line Items]
Revenue, remaining performance obligation, amount											$ 1,000,000				$ 1,000,000
Revenue, remaining performance obligation, expected timing of satisfaction, period											12 months				12 months
Trade Names
Property, Plant and Equipment [Line Items]
Indefinite lived intangible assets											$ 7,100,000				$ 7,100,000
Write off of the reporting unit trade name												4,200,000
Accumulated Net Gain (Loss) from Cash Flow Hedges
Property, Plant and Equipment [Line Items]
Accumulated other comprehensive income																			$ 24,400,000
Forecast
Property, Plant and Equipment [Line Items]
Monthly amortization of deferred hedge gains														$ 300,000
Forecast | Subsequent Event
Property, Plant and Equipment [Line Items]
Monthly amortization of deferred hedge gains																$ 400,000
C O V I D19 Pandemic
Property, Plant and Equipment [Line Items]
Advance medicare payments											100,000	39,500,000			39,600,000
Proceeds from provider relief funding											9,100,000	26,300,000			35,400,000
Advance insurance carrier payments												5,000,000
Repayment of advance medicare payments											30,200,000
Repayment of insurance advances											3,700,000	1,300,000			5,000,000
Deferred social security taxes											8,100,000	$ 16,300,000			$ 8,100,000
Refundable claim percentage												50.00%
Increase (decrease) in social security tax, employer, deferral, CARES Act											$ 7,700,000
Medic Vision
Property, Plant and Equipment [Line Items]
Equity interest percentage							12.50%				14.21%				14.21%
Investment at cost					$ 200,000		$ 1,000,000
Option to purchase additional equity method investment							$ 1,400,000
Ownership interest percentage acquired					1.96%
Initial ownership percentage after dilution					12.25%
Total net assets											$ 1,200,000				$ 1,200,000
Turner Imaging Systems
Property, Plant and Equipment [Line Items]
Investment at cost						$ 2,000,000
Shares purchased (in shares) | shares						2,100,000
Preferred stock issued upon conversion (in shares) | shares																				80,000
WhiteRabbit.ai Inc.
Property, Plant and Equipment [Line Items]
Investment at cost	$ 1,000,000
Payments to fund loan to related parties	$ 2,500,000
Arizona Diagnostic Radiology Group LLC | RadNet
Property, Plant and Equipment [Line Items]
Equity interest percentage																		49.00%
Arizona Diagnostic Radiology Group LLC | CHI National Services Inc.
Property, Plant and Equipment [Line Items]
Equity interest percentage																		51.00%
Santa Monica Imaging Group
Property, Plant and Equipment [Line Items]
Payments to acquire additional interest in subsidiaries								$ 1,600,000
Santa Monica Imaging Group | RadNet
Property, Plant and Equipment [Line Items]
Equity interest percentage			35.00%																			40.00%
Loss on equity method investment			$ 2,000
Santa Monica Imaging Group | Cedars Sinai Medical Center
Property, Plant and Equipment [Line Items]
Equity interest percentage																						60.00%
Additional equity interest acquired			5.00%
Investment owned, at fair value			$ 134,000
2016 Caps | LIBOR
Property, Plant and Equipment [Line Items]
Basis spread on variable rate																							2.00%
September 2020
Property, Plant and Equipment [Line Items]
Notional amounts																							$ 150,000,000
October 2020
Property, Plant and Equipment [Line Items]
Notional amounts																							$ 350,000,000
Radiologix
Property, Plant and Equipment [Line Items]
Contract loss accrual																									$ 8,900,000
Hudson Valley Radiology Associates | Primedex Health Systems Inc. and Radiologix
Property, Plant and Equipment [Line Items]
Unfavorable lease contracts acquired, gross													4,000,000
Unfavorable lease contracts acquired													2,800,000
Garden State Radiology Network LLC
Property, Plant and Equipment [Line Items]
Equity interest percentage																								49.00%
Investment at cost										$ 2,200,000
Loss on equity method investment		$ (1,300,000)
Nulogix, Inc.
Property, Plant and Equipment [Line Items]
Equity interest percentage		75.00%		25.00%
Investment at cost		$ 1,500,000		$ 2,000,000
Health Insurance
Property, Plant and Equipment [Line Items]
Self-insurance accrual											6,300,000	$ 6,600,000			6,300,000
Leasehold improvements
Property, Plant and Equipment [Line Items]
Impairment of long lived asset											7,100,000
Minimum | Blue Shield
Property, Plant and Equipment [Line Items]
Stop loss policy claim amount											$ 250,000				250,000
Minimum | Dignity Health | Glendale Advanced Imaging | Joint Venture
Property, Plant and Equipment [Line Items]
Economic interest											35.00%
Minimum | Propery and equipment, net
Property, Plant and Equipment [Line Items]
PP&E useful life											3 years
Minimum | Leasehold improvements
Property, Plant and Equipment [Line Items]
PP&E useful life											3 years
Maximum | Blue Shield
Property, Plant and Equipment [Line Items]
Stop loss policy claim amount											$ 1,000,000				1,000,000
Maximum | Dignity Health | Glendale Advanced Imaging | Joint Venture
Property, Plant and Equipment [Line Items]
Economic interest											55.00%
Maximum | Propery and equipment, net
Property, Plant and Equipment [Line Items]
PP&E useful life											15 years
Maximum | Leasehold improvements
Property, Plant and Equipment [Line Items]
PP&E useful life											15 years
Paycheck Protection Program Loans | C O V I D19 Pandemic
Property, Plant and Equipment [Line Items]
Proceeds from loans												4,000,000
Barclays
Property, Plant and Equipment [Line Items]
Total credit facilities outstanding											$ 0	0			0
Net service fee revenue | eRAD
Property, Plant and Equipment [Line Items]
Service fee revenue											$ 10,500,000	$ 8,600,000	$ 10,100,000
Restated Plan
Property, Plant and Equipment [Line Items]
Shares authorized (in shares) | shares																	16,500,000
Restated Plan | Minimum
Property, Plant and Equipment [Line Items]
Share-based payment award, award vesting period											3 years
Share-based payment award, expiration period											5 years
Restated Plan | Minimum | Shares issuable upon the exercise of stock options
Property, Plant and Equipment [Line Items]
Share-based payment award, award vesting period											3 years
Share-based payment award, expiration period											5 years
Restated Plan | Maximum
Property, Plant and Equipment [Line Items]
Share-based payment award, award vesting period											5 years
Share-based payment award, expiration period											10 years
Restated Plan | Maximum | Shares issuable upon the exercise of stock options
Property, Plant and Equipment [Line Items]
Share-based payment award, award vesting period											5 years
Share-based payment award, expiration period											10 years
US Attorneys Office For The Western District of New York
Property, Plant and Equipment [Line Items]
Loss contingency accrual liability																					$ 2,300,000
Settled Litigation | US Attorneys Office For The Western District of New York
Property, Plant and Equipment [Line Items]
Litigation settlement									$ 2,200,000
2016 Caps
Property, Plant and Equipment [Line Items]
Interest rate caps premium liability											$ 5,300,000				$ 5,300,000
2019 SWAPS
Property, Plant and Equipment [Line Items]
Notional amounts																					$ 500,000,000
Number of forward interest rate cap agreements | agreement																					4,000
2019 SWAPS | 2019 SWAPS - Interest Rate Contracts
Property, Plant and Equipment [Line Items]
Notional amounts																					$ 100,000,000
2019 SWAPS | 2019 SWAPS - Interest Rate Contracts | LIBOR
Property, Plant and Equipment [Line Items]
Basis spread on variable rate																					1.96%
2019 SWAPS | October 2023
Property, Plant and Equipment [Line Items]
Notional amounts																					$ 50,000,000
2019 SWAPS | October 2025
Property, Plant and Equipment [Line Items]
Notional amounts																					200,000,000
2019 SWAPS1 | 2019 SWAPS - Interest Rate Contracts
Property, Plant and Equipment [Line Items]
Notional amounts																					$ 400,000,000
2019 SWAPS1 | 2019 SWAPS - Interest Rate Contracts | LIBOR
Property, Plant and Equipment [Line Items]
Basis spread on variable rate																					2.05%
Promissory note | Turner Imaging Systems
Property, Plant and Equipment [Line Items]
Convertible promissory note			$ 143,000