DEBT - Credit Facility (Details)			3 Months Ended	9 Months Ended
	Sep. 15, 2021 USD ($)	Dec. 10, 2019 USD ($)	Sep. 30, 2021 USD ($)	Sep. 30, 2021 USD ($)	Sep. 30, 2020 USD ($)	Dec. 31, 2020 USD ($)
Line of Credit Facility [Line Items]
Letters of credit outstanding			$ 200,000	$ 200,000		$ 200,000
Leverage ratio	2.50
Ratio of Debt to EBITDA Increase	0.50
Write-off of previously-capitalized debt issuance costs				1,066,000	$ 0
Amortization of debt issuance costs				3,756,000	2,241,000
Amortization of debt discount				22,297,000	12,429,000
Letter of Credit
Line of Credit Facility [Line Items]
Maximum borrowing capacity	$ 20,000,000
Line of Credit | Credit Agreement
Line of Credit Facility [Line Items]
Line of credit outstanding			0	0
Potential additional borrowing capacity	$ 116,000,000
Credit agreement, ratio of debt to EBITDA	3.00
Premium percentage	1.00%
Premium percentage period	6 months
Collateral, percent of domestic subsidiaries equity	100.00%
Collateral, percent of voting equity	65.00%
Collateral, percent of non-voting equity	100.00%
Line of Credit | Credit Agreement | Revolving Credit Facility
Line of Credit Facility [Line Items]
Maximum borrowing capacity	$ 200,000,000
Capacity available for general corporate purchases	80,000,000
Covenant threshold	$ 20,000,000
Letter of credit fronting fee percentage	0.125%
Debt issuance costs	$ 2,800,000
Interest expense				3,000,000
Unused commitment fees				1,800,000
Amortization of debt issuance costs				1,200,000
Line of Credit | Credit Agreement | Delayed Draw Term Loan
Line of Credit Facility [Line Items]
Maximum borrowing capacity	250,000,000
Debt issuance costs	3,500,000
Unamortized debt discount	$ 2,500,000
Interest expense				700,000
Unused commitment fees				400,000
Amortization of debt issuance costs				200,000
Amortization of debt discount				$ 100,000
Line of Credit | Credit Agreement | Fed Funds Effective Rate | Revolving Credit Facility
Line of Credit Facility [Line Items]
Basis spread on variable rate	0.50%
Line of Credit | Credit Agreement | LIBOR | Revolving Credit Facility
Line of Credit Facility [Line Items]
Basis spread on variable rate	1.00%
Line of Credit | Credit Agreement | Minimum | Revolving Credit Facility
Line of Credit Facility [Line Items]
Unused capacity, commitment fee percentage	0.25%
Letter of credit participation fee percentage	2.25%
Line of Credit | Credit Agreement | Minimum | LIBOR | Revolving Credit Facility
Line of Credit Facility [Line Items]
Basis spread on variable rate	2.25%
Line of Credit | Credit Agreement | Minimum | LIBOR | Delayed Draw Term Loan
Line of Credit Facility [Line Items]
Basis spread on variable rate	3.75%
Line of Credit | Credit Agreement | Minimum | Base Rate | Revolving Credit Facility
Line of Credit Facility [Line Items]
Basis spread on variable rate	1.25%
Line of Credit | Credit Agreement | Minimum | Base Rate | Delayed Draw Term Loan
Line of Credit Facility [Line Items]
Basis spread on variable rate	2.75%
Line of Credit | Credit Agreement | Maximum | Revolving Credit Facility
Line of Credit Facility [Line Items]
Unused capacity, commitment fee percentage	0.50%
Letter of credit participation fee percentage	2.75%
Line of Credit | Credit Agreement | Maximum | LIBOR | Revolving Credit Facility
Line of Credit Facility [Line Items]
Basis spread on variable rate	2.75%
Line of Credit | Credit Agreement | Maximum | LIBOR | Delayed Draw Term Loan
Line of Credit Facility [Line Items]
Basis spread on variable rate	4.00%
Line of Credit | Credit Agreement | Maximum | Base Rate | Revolving Credit Facility
Line of Credit Facility [Line Items]
Basis spread on variable rate	1.75%
Line of Credit | Credit Agreement | Maximum | Base Rate | Delayed Draw Term Loan
Line of Credit Facility [Line Items]
Basis spread on variable rate	3.00%
Line of Credit | Amended Revolving Credit Facility | Revolving Credit Facility
Line of Credit Facility [Line Items]
Maximum borrowing capacity		$ 500,000,000
Debt term		5 years
Line of credit outstanding						$ 0
Write-off of previously-capitalized debt issuance costs			$ 1,100,000
Interest expense					3,200,000
Unused commitment fees					1,100,000
Amortization of debt issuance costs					800,000
Line of Credit | Amended Revolving Credit Facility | LIBOR | Revolving Credit Facility
Line of Credit Facility [Line Items]
Interest expense					$ 1,300,000