Debt Instrument, Number of Loans Received

No definition available.

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- Definition

Debt Instrument, Periodic Payment, Percent

+ References

No definition available.

+ Details

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Period Type:	duration

- Definition

Debt Instrument, Periodic Payment Terms, Amortization Increase

+ References

No definition available.

+ Details

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Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Line of Credit Facility, Increase Borrowing Capacity

+ References

No definition available.

+ Details

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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=116634182&loc=SL114868664-224227

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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

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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
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+ Details

Name:	us-gaap_DebtInstrumentFaceAmount
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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
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+ Details

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Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

Contractual interest rate for funds borrowed, under the debt agreement.

+ References

+ Details

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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

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Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Amount of the required periodic payments applied to principal.

+ References

+ Details

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Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Period of time between issuance and maturity of debt instrument, in PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

+ References

No definition available.

+ Details

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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
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-Section 45
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+ Details

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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

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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

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
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+ Details

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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

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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

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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

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-SubTopic 10
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+ Details

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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

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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

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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

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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

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- Details

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- Details

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- Details

Name:	us-gaap_LongtermDebtTypeAxis=rdnt_FirstLienCreditAgreementSeventhAmendmentMember
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Period Type:

- Details

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Period Type:

- Details

Name:	us-gaap_LineOfCreditFacilityAxis=rdnt_BarclaysMember
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Balance Type:
Period Type:

- Details

Name:	us-gaap_LongtermDebtTypeAxis=us-gaap_LetterOfCreditMember
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Balance Type:
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- Details

Name:	us-gaap_LineOfCreditFacilityAxis=rdnt_SunTrustMember
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Balance Type:
Period Type:

- Details

Name:	us-gaap_LongtermDebtTypeAxis=us-gaap_LineOfCreditMember
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- Details

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Balance Type:
Period Type:

- Details

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- Details

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- Details

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Data Type:	na
Balance Type:
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- Details

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Balance Type:
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- Details

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- Details

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CREDIT FACILITY AND NOTES PAYABLE (Details Narrative)				9 Months Ended	12 Months Ended
CREDIT FACILITY AND NOTES PAYABLE (Details Narrative)	Apr. 18, 2019 USD ($)	Aug. 31, 2018	Jul. 01, 2016	Sep. 30, 2020 USD ($) loan	Dec. 31, 2018 USD ($)	Dec. 31, 2019 USD ($)	Aug. 22, 2017 USD ($)
Debt Instrument [Line Items]
Total credit facilities outstanding				$ 0		$ 0
Deferred financing costs, net of accumulated amortization				1,900,000		1,600,000
Term Loan
Debt Instrument [Line Items]
Debt instrument face value				673,227,000
FirstLienTermLoansAMember
Debt Instrument [Line Items]
Discounts on term loans				10,700,000
First Lien Credit Agreement Seventh Amendment
Debt Instrument [Line Items]
Deferred financing costs, net of accumulated amortization	$ 700,000
Debt issuance costs	4,400,000
Debt discount	2,100,000
Amortization of deferred issuance costs	1,600,000
Revolving Credit Facility
Debt Instrument [Line Items]
Letters of credit outstanding				6,300,000
Deferred financing costs, net of accumulated amortization				$ 1,900,000
Effective interest rate				6.00%
Barclays \| Revolving Credit Facility
Debt Instrument [Line Items]
Line of credit facility, remaining borrowing capacity				$ 188,700,000
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				620,727,000
Discounts on term loans				10,669,000		13,579,000
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				52,500,000
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 \| Medium-term Notes
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
Paycheck Protection Program Loans
Debt Instrument [Line Items]
Interest rate, stated percentage				1.00%
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 \| 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				3.75%
Eurodollar \| Pricing Level III \| Restated Agreement \| Revolving Credit Facility
Debt Instrument [Line Items]
Basis spread on variable rate		2.00%		2.00%
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				2.75%
Base Rate \| Pricing Level III \| Restated Agreement \| Revolving Credit Facility
Debt Instrument [Line Items]
Basis spread on variable rate		1.00%
COVID-19 Pandemic \| Paycheck Protection Program Loans
Debt Instrument [Line Items]
Debt instrument face value				$ 4,000,000.0
Interest rate, stated percentage				1.00%
PPP loans, maturity term				2 years
Number of PPP loans received \| loan				4