Allowance for Doubtful Accounts - Allowance for doubtful accounts (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Accounts receivable
Accounts receivable, Allowance for doubtful accounts, beginning balance	$ 46,526	$ 74,389	$ 51,052	$ 39,903
Write-Offs	(75)	(9,987)	(7,380)	(14,396)
Bad Debt Expense	3,792	1,897	6,571	4,083
Notes receivable
Notes receivable, Allowance for doubtful accounts, beginning balance	14,576	17,891	16,749	12,490
Accounts receivable, Allowance for doubtful accounts, ending balance	50,243	66,299	50,243	66,299
Write-Offs	39	(2,168)	(2,770)	(2,168)
Bad Debt Expense	(498)	1,964	138	1,838
Notes receivable, Allowance for doubtful accounts, ending balance	14,117	17,687	14,117	17,687
Total accounts and notes receivable
Allowance for doubtful accounts, beginning balance	61,102	92,280	67,801	52,393
Write-Offs	(36)	(12,155)	(10,150)	(16,564)
Bad Debt Expense	3,294	3,861	6,709	5,921
Allowance for doubtful accounts, ending balance	64,360	83,986	64,360	83,986
Accounts receivable recovered after write off	100	800	100	800
Cumulative effect of ASC 326 adoption
Accounts receivable
Accounts receivable, Allowance for doubtful accounts, beginning balance				36,709
Notes receivable
Notes receivable, Allowance for doubtful accounts, beginning balance				5,527
Total accounts and notes receivable
Allowance for doubtful accounts, beginning balance				42,236
Standard notes receivable
Notes receivable
Notes receivable, Allowance for doubtful accounts, beginning balance	12,993	11,654	13,258	6,667
Write-Offs	0	(1,721)	(9)	(1,721)
Bad Debt Expense	(459)	1,936	(715)	1,687
Notes receivable, Allowance for doubtful accounts, ending balance	12,534	11,869	12,534	11,869
Standard notes receivable | Cumulative effect of ASC 326 adoption
Notes receivable
Notes receivable, Allowance for doubtful accounts, beginning balance				5,236
Elevated risk notes receivable
Notes receivable
Notes receivable, Allowance for doubtful accounts, beginning balance	1,583	6,237	3,491	5,823
Write-Offs	39	(447)	(2,761)	(447)
Bad Debt Expense	(39)	28	853	151
Notes receivable, Allowance for doubtful accounts, ending balance	$ 1,583	$ 5,818	$ 1,583	5,818
Elevated risk notes receivable | Cumulative effect of ASC 326 adoption
Notes receivable
Notes receivable, Allowance for doubtful accounts, beginning balance				$ 291