NOTES PAYABLE, FINANCE LEASES, AND COMMERCIAL BANK FINANCING - Bank Credit Agreements (Details)		9 Months Ended
Mar. 17, 2020 USD ($)	Sep. 30, 2020 USD ($)
Debt Instrument [Line Items]
Borrowings under revolving credit facility exceed total commitments (as a percent)		35.00%
STG Revolving Credit Facility
Debt Instrument [Line Items]
Maximum borrowing capacity		$ 650,000,000
Debt term		5 years
Drew down from credit facility	$ 648,000,000
First lien leverage ratio		4.5
Borrowings outstanding		$ 0
DSG Revolving Credit Facility
Debt Instrument [Line Items]
Maximum borrowing capacity		$ 650,000,000
Debt term		5 years
Drew down from credit facility	$ 225,000,000
First lien leverage ratio		6.25
Borrowings outstanding		$ 0
LIBOR \| STG Revolving Credit Facility
Debt Instrument [Line Items]
Basis spread on variable rate		2.00%
LIBOR \| DSG Revolving Credit Facility
Debt Instrument [Line Items]
Basis spread on variable rate		3.00%

Debt Instrument, Covenant, First Lien Leverage Ratio Test, Borrowings Exceed Total Commitments, Percent

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- Definition

Debt Instrument, Covenant, Required Prepayment, First Lien Leverage Ratio

+ References

No definition available.

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- Definition

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

+ References

No definition available.

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- 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.

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- 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.

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- 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))
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- 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

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- Definition

Amount of cash inflow from contractual arrangement with the lender, including but not limited to, letter of credit, standby letter of credit and revolving credit arrangements.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 14
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-Name Accounting Standards Codification
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