Allowance for Doubtful Accounts - Notes Receivable Disaggregated by Vintage Year (Details) $ in Thousands	3 Months Ended
	Mar. 31, 2020 USD ($)
Financing Receivable, Credit Quality Indicator [Line Items]
Current-period gross write-offs	$ 0
Current-period recoveries	0
Current-period net write-offs	0
Standard note receivable
Financing Receivable, Credit Quality Indicator [Line Items]
2020	6,810
2019	16,058
2018	17,745
2017	27,066
2016	1,989
Prior	1,606
Financing Receivable, before Allowance for Credit Loss, Total	71,274
Current-period gross write-offs	0
Elevated risk note receivable
Financing Receivable, Credit Quality Indicator [Line Items]
2020	0
2019	0
2018	397
2017	5,511
2016	0
Prior	2,457
Financing Receivable, before Allowance for Credit Loss, Total	8,365
Current-period gross write-offs	$ 0