Long-Term Debt - HPS Credit Facility (Details) - USD ($)	1 Months Ended	9 Months Ended
	May 31, 2020	Sep. 30, 2020	Sep. 30, 2019
Line of Credit Facility [Line Items]
Deferred loan cost amortization		$ 3,021,000	$ 1,496,000
Revolving Credit Facility | HPS Credit Facility | Line of Credit | SDC U.S. SmilePay SPV
Line of Credit Facility [Line Items]
Debt term	5 years
Maximum borrowing capacity	$ 400,000,000
Debt discount	12,000,000
Additional aggregate principal available	100,000,000
Financing costs incurred	187,000
Write off of deferred debt issuance cost	1,594,000
Deferred financing costs	11,784,000
Deferred loan cost amortization		842,000
Receivables collateralized on outstanding debt		345,996,000
Debt instrument, covenant minimum monthly liquidity	$ 100,000,000
Debt instrument, refinancing fee, percentage of principal amount prepaid, year one	4.00%
Debt instrument, refinancing fee, percentage of principal amount prepaid, year two	4.00%
Debt instrument, refinancing fee, percentage of principal amount prepaid, year three	3.00%
Debt instrument, refinancing fee, percentage of principal amount prepaid, year four	2.00%
Debt instrument, refinancing fee, percentage of principal amount prepaid, year five	1.00%
Long-term debt, including unamortized financing costs		$ 404,569,000
Revolving Credit Facility | HPS Credit Facility | Line of Credit | SDC U.S. SmilePay SPV | London Interbank Offered Rate (LIBOR) | Minimum
Line of Credit Facility [Line Items]
Basis spread on variable rate	1.75%
Revolving Credit Facility | HPS Credit Facility | Line of Credit | SDC U.S. SmilePay SPV | LIBOR - Payable In Cash
Line of Credit Facility [Line Items]
Basis spread on variable rate	7.50%
Revolving Credit Facility | HPS Credit Facility | Line of Credit | SDC U.S. SmilePay SPV | LIBOR - Payable In Kind
Line of Credit Facility [Line Items]
Basis spread on variable rate	3.25%