Debt Instrument, Extension Period

No definition available.

Name:	rdnt_DebtInstrumentExtensionPeriod
Namespace Prefix:	rdnt_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

Debt Instrument, Periodic Payment, Percent

+ References

No definition available.

+ Details

Name:	rdnt_DebtInstrumentPeriodicPaymentPercent
Namespace Prefix:	rdnt_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Debt Instrument, Periodic Payment Terms, Amortization Increase

+ References

No definition available.

+ Details

Name:	rdnt_DebtInstrumentPeriodicPaymentTermsAmortizationIncrease
Namespace Prefix:	rdnt_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Line of Credit Facility, Increase Borrowing Capacity

+ References

No definition available.

+ Details

Name:	rdnt_LineofCreditFacilityIncreaseBorrowingCapacity
Namespace Prefix:	rdnt_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

The amount of amortization of deferred charges applied against earnings during the period.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 220
-SubTopic 10
-Section S99
-Paragraph 2
-Subparagraph (SX 210.5-03.3)
-URI http://asc.fasb.org/extlink&oid=120395209&loc=SL114868664-224227

+ Details

Name:	us-gaap_AmortizationOfDeferredCharges
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Percentage points added to the reference rate to compute the variable rate on the debt instrument.

+ References

No definition available.

+ Details

Name:	us-gaap_DebtInstrumentBasisSpreadOnVariableRate1
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Face (par) amount of debt instrument at time of issuance.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 45
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=119993939&loc=d3e28551-108399

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 55
-Paragraph 8
-URI http://asc.fasb.org/extlink&oid=114775985&loc=d3e28878-108400

+ Details

Name:	us-gaap_DebtInstrumentFaceAmount
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Effective interest rate for the funds borrowed under the debt agreement considering interest compounding and original issue discount or premium.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 470
-SubTopic 20
-Section 50
-Paragraph 6
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=120520924&loc=SL6036836-161870

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 45
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=119993939&loc=d3e28551-108399

Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.22(a)(1))
-URI http://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682

+ Details

Name:	us-gaap_DebtInstrumentInterestRateEffectivePercentage
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

No definition available.

+ Details

Name:	us-gaap_DebtInstrumentLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Amount of the required periodic payments applied to principal.

+ References

+ Details

Name:	us-gaap_DebtInstrumentPeriodicPaymentPrincipal
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Amount, after accumulated amortization, of debt discount.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 45
-Paragraph 1A
-URI http://asc.fasb.org/extlink&oid=119993939&loc=d3e28541-108399

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 55
-Paragraph 8
-URI http://asc.fasb.org/extlink&oid=114775985&loc=d3e28878-108400

+ Details

Name:	us-gaap_DebtInstrumentUnamortizedDiscount
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Amount of debt discount to be amortized within one year or within the normal operating cycle, if longer.

+ References

+ Details

Name:	us-gaap_DebtInstrumentUnamortizedDiscountCurrent
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Amount, before accumulated amortization, of debt issuance costs. Includes, but is not limited to, legal, accounting, underwriting, printing, and registration costs.

+ References

+ Details

Name:	us-gaap_DeferredFinanceCostsGross
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Amount, after accumulated amortization, of debt issuance costs. Includes, but is not limited to, legal, accounting, underwriting, printing, and registration costs.

+ References

+ Details

Name:	us-gaap_DeferredFinanceCostsNet
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Amount, after accumulated amortization, of debt issuance costs classified as noncurrent. Includes, but is not limited to, legal, accounting, underwriting, printing, and registration costs.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 45
-Paragraph 3
-URI http://asc.fasb.org/extlink&oid=119993939&loc=d3e28555-108399

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.17)
-URI http://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682

+ Details

Name:	us-gaap_DeferredFinanceCostsNoncurrentNet
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

The total amount of the contingent obligation under letters of credit outstanding as of the reporting date.

+ References

No definition available.

+ Details

Name:	us-gaap_LettersOfCreditOutstandingAmount
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

The carrying value as of the balance sheet date of the current and noncurrent portions of long-term obligations drawn from a line of credit, which is a bank's commitment to make loans up to a specific amount. Examples of items that might be included in the application of this element may consist of letters of credit, standby letters of credit, and revolving credit arrangements, under which borrowings can be made up to a maximum amount as of any point in time conditional on satisfaction of specified terms before, as of and after the date of drawdowns on the line. Includes short-term obligations that would normally be classified as current liabilities but for which (a) postbalance sheet date issuance of a long term obligation to refinance the short term obligation on a long term basis, or (b) the enterprise has entered into a financing agreement that clearly permits the enterprise to refinance the short-term obligation on a long term basis and the following conditions are met (1) the agreement does not expire within 1 year and is not cancelable by the lender except for violation of an objectively determinable provision, (2) no violation exists at the BS date, and (3) the lender has entered into the financing agreement is expected to be financially capable of honoring the agreement.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02(22))
-URI http://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-03(16))
-URI http://asc.fasb.org/extlink&oid=120398452&loc=d3e534808-122878

Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.7-03(16))
-URI http://asc.fasb.org/extlink&oid=120400017&loc=d3e572229-122910

+ Details

Name:	us-gaap_LineOfCredit
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

The fee, expressed as a percentage of the line of credit facility, for the line of credit facility regardless of whether the facility has been used.

+ References

No definition available.

+ Details

Name:	us-gaap_LineOfCreditFacilityCommitmentFeePercentage
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Maximum borrowing capacity under the credit facility without consideration of any current restrictions on the amount that could be borrowed or the amounts currently outstanding under the facility.

+ References

+ Details

Name:	us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Amount of borrowing capacity currently available under the credit facility (current borrowing capacity less the amount of borrowings outstanding).

+ References

+ Details

Name:	us-gaap_LineOfCreditFacilityRemainingBorrowingCapacity
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

The fee, expressed as a percentage of the line of credit facility, for available but unused credit capacity under the credit facility.

+ References

No definition available.

+ Details

Name:	us-gaap_LineOfCreditFacilityUnusedCapacityCommitmentFeePercentage
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Details

Name:	us-gaap_LongtermDebtTypeAxis=rdnt_TermLoanMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_LongtermDebtTypeAxis=rdnt_FirstLienTermLoansAMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_LongtermDebtTypeAxis=rdnt_FirstLienCreditAgreementSeventhAmendmentMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_CreditFacilityAxis=us-gaap_RevolvingCreditFacilityMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_LineOfCreditFacilityAxis=rdnt_BarclaysMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_LongtermDebtTypeAxis=us-gaap_LetterOfCreditMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_LineOfCreditFacilityAxis=rdnt_SunTrustMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_LongtermDebtTypeAxis=us-gaap_LineOfCreditMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DebtInstrumentAxis=rdnt_FirstLienTermLoanMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DebtInstrumentAxis=rdnt_RestatedAgreementMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DebtInstrumentAxis=rdnt_FirstLienCreditAgreementMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DebtInstrumentAxis=rdnt_FirstLienCreditAgreementEighthAmendmentMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DebtInstrumentAxis=rdnt_FirstLienCreditAgreementSixthAmendmentMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_LongtermDebtTypeAxis=us-gaap_MediumTermNotesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	rdnt_LeverageRatioAxis=rdnt_PricingLevelIIIMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_VariableRateAxis=us-gaap_EurodollarMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	rdnt_LeverageRatioAxis=rdnt_LeverageRatioThreeMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_VariableRateAxis=us-gaap_BaseRateMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

CREDIT FACILITY AND NOTES PAYABLE (Details Narrative) - USD ($)					3 Months Ended	12 Months Ended
	Aug. 18, 2019	Apr. 18, 2019	Aug. 31, 2018	Jul. 01, 2016	Mar. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Debt Instrument [Line Items]
Total credit facilities outstanding					$ 0	$ 0
Deferred financing costs					1,590,000	1,767,000
Deferred financing costs, net of accumulated amortization					1,600,000	1,800,000
Term Loan
Debt Instrument [Line Items]
Debt instrument face value					651,580,000
FirstLienTermLoansAMember
Debt Instrument [Line Items]
Discounts on term loans					8,700,000
First Lien Credit Agreement Seventh Amendment
Debt Instrument [Line Items]
Debt issuance costs		$ 4,400,000
Debt discount		2,100,000
Deferred financing costs, net of accumulated amortization		700,000
Amortization of deferred issuance costs		1,600,000
Revolving Credit Facility
Debt Instrument [Line Items]
Letters of credit outstanding					$ 7,900,000
Effective interest rate					5.75%
Deferred financing costs, net of accumulated amortization					$ 1,600,000
Barclays \| Revolving Credit Facility
Debt Instrument [Line Items]
Line of credit facility, remaining borrowing capacity					$ 187,100,000
Barclays \| Revolving Credit Facility \| Letter of Credit
Debt Instrument [Line Items]
Commitment fee percentage					0.25%
Unused capacity, commitment fee percentage					0.50%
SunTrust \| Term Loan
Debt Instrument [Line Items]
Periodic payment, principal					$ 800,000
Periodic payment, percent					5.00%
Periodic payment amortization increase							$ 400,000
SunTrust \| Revolving Credit Facility \| Line of Credit
Debt Instrument [Line Items]
Maximum borrowing capacity					$ 30,000,000.0
First Lien Term Loan \| Term Loan
Debt Instrument [Line Items]
Debt instrument face value					601,330,000
Discounts on term loans					8,730,000	9,699,000
First Lien Term Loan \| Barclays \| Term Loan
Debt Instrument [Line Items]
Periodic payment, principal					9,700,000
Restated Agreement \| Term Loan
Debt Instrument [Line Items]
Debt instrument face value					50,250,000
First Lien Credit Agreement \| Barclays \| Revolving Credit Facility \| Line of Credit
Debt Instrument [Line Items]
Total credit facilities outstanding					0	$ 0
First Lien Credit Agreement \| SunTrust \| Revolving Credit Facility \| Line of Credit
Debt Instrument [Line Items]
Total credit facilities outstanding					0
First Lien Credit Agreement Eighth Amendment \| Barclays \| Revolving Credit Facility \| Line of Credit
Debt Instrument [Line Items]
Maximum borrowing capacity					195,000,000.0
Line of credit facility, increase borrowing capacity					57,500,000
Debt issuance costs					$ 700,000
First Lien Credit Agreement, Sixth Amendment \| Term loan
Debt Instrument [Line Items]
Total credit facilities outstanding		100,000,000.0
First Lien Credit Agreement, Sixth Amendment \| Revolving Credit Facility \| Line of Credit
Debt Instrument [Line Items]
Line of credit facility, increase borrowing capacity		$ 20,000,000.0
Extension period	2 years
Pricing Level III \| Restated Agreement \| Revolving Credit Facility
Debt Instrument [Line Items]
Commitment fee percentage			2.00%
Unused capacity, commitment fee percentage			0.35%
Eurodollar \| First Lien Credit Agreement, Sixth Amendment \| Term Loan
Debt Instrument [Line Items]
Basis spread on variable rate						1.00%
Eurodollar \| First Lien Credit Agreement, Sixth Amendment \| Revolving Credit Facility \| Line of Credit
Debt Instrument [Line Items]
Effective interest rate					1.00%
Eurodollar \| >3.50x but ≤ 4.00x \| First Lien Credit Agreement \| Revolving Credit Facility \| Line of Credit
Debt Instrument [Line Items]
Basis spread on variable rate				3.50%
Eurodollar \| >3.50x but ≤ 4.00x \| First Lien Credit Agreement, Sixth Amendment \| Revolving Credit Facility \| Line of Credit
Debt Instrument [Line Items]
Basis spread on variable rate					3.50%
Eurodollar \| Pricing Level III \| Restated Agreement \| Revolving Credit Facility
Debt Instrument [Line Items]
Basis spread on variable rate			2.00%		0.25%
Base Rate \| First Lien Credit Agreement, Sixth Amendment \| Revolving Credit Facility \| Line of Credit
Debt Instrument [Line Items]
Effective interest rate					3.25%
Base Rate \| >3.50x but ≤ 4.00x \| First Lien Credit Agreement \| Revolving Credit Facility \| Line of Credit
Debt Instrument [Line Items]
Basis spread on variable rate				2.50%
Base Rate \| >3.50x but ≤ 4.00x \| First Lien Credit Agreement, Sixth Amendment \| Revolving Credit Facility \| Line of Credit
Debt Instrument [Line Items]
Basis spread on variable rate					2.50%
Base Rate \| Pricing Level III \| Restated Agreement \| Revolving Credit Facility
Debt Instrument [Line Items]
Basis spread on variable rate			1.00%