Allowance for Doubtful Accounts - Age Analysis of Past-Due Note Receivable (Details) $ in Thousands	Dec. 31, 2020 USD ($)
Financing Receivable, Past Due [Line Items]
Notes Receivable	$ 14,467
0-90 Days
Financing Receivable, Past Due [Line Items]
Notes Receivable	1,254
91 - 180 Days
Financing Receivable, Past Due [Line Items]
Notes Receivable	4,124
Greater than 181 Days
Financing Receivable, Past Due [Line Items]
Notes Receivable	9,089
Standard notes receivable
Financing Receivable, Past Due [Line Items]
Notes Receivable	8,507
Standard notes receivable | 0-90 Days
Financing Receivable, Past Due [Line Items]
Notes Receivable	1,001
Standard notes receivable | 91 - 180 Days
Financing Receivable, Past Due [Line Items]
Notes Receivable	3,794
Standard notes receivable | Greater than 181 Days
Financing Receivable, Past Due [Line Items]
Notes Receivable	3,712
Elevated risk notes receivable
Financing Receivable, Past Due [Line Items]
Notes Receivable	5,960
Elevated risk notes receivable | 0-90 Days
Financing Receivable, Past Due [Line Items]
Notes Receivable	253
Elevated risk notes receivable | 91 - 180 Days
Financing Receivable, Past Due [Line Items]
Notes Receivable	330
Elevated risk notes receivable | Greater than 181 Days
Financing Receivable, Past Due [Line Items]
Notes Receivable	$ 5,377