Allowance for Doubtful Accounts - Allowance for doubtful accounts (Details) - USD ($) $ in Thousands	3 Months Ended	6 Months Ended
	Jun. 30, 2020	Jun. 30, 2020	Jun. 30, 2019	Jan. 01, 2020
Accounts receivable
Accounts receivable, Allowance for doubtful accounts, beginning balance	$ 74,389	$ 39,903
One-time adjustment	66,299	39,903
Write-Offs	(9,987)	(14,396)
Bad Debt Expense	1,897	4,083
Accounts receivable, Allowance for doubtful accounts, ending balance	66,299	66,299
Notes receivable
Notes receivable, Allowance for doubtful accounts, beginning balance	17,687	17,687
One-time adjustment	17,687	17,687
Write-Offs	(2,168)	(2,168)
Bad Debt Expense	1,964	1,838
Notes receivable, Allowance for doubtful accounts, ending balance	17,891	12,490
Allowance for doubtful accounts, beginning balance	92,280	52,393
One-time adjustment	83,986	52,393
Write-Offs	(12,155)	(16,564)
Bad Debt Expense	3,861	5,921	$ 21,465
Allowance for doubtful accounts, ending balance	83,986	83,986
Accounts receivable recovered after write off	800	800
Cumulative Impact from Adopting ASC 326 Guidance
Accounts receivable
One-time adjustment				$ 36,709
Notes receivable
One-time adjustment				5,527
One-time adjustment				42,236
Standard notes receivable
Notes receivable
Notes receivable, Allowance for doubtful accounts, beginning balance	11,869	11,869
One-time adjustment	11,869	11,869
Write-Offs	(1,721)	(1,721)
Bad Debt Expense	1,936	1,687
Notes receivable, Allowance for doubtful accounts, ending balance	11,654	6,667
Standard notes receivable | Cumulative Impact from Adopting ASC 326 Guidance
Notes receivable
One-time adjustment				5,236
Elevated risk notes receivable
Notes receivable
Notes receivable, Allowance for doubtful accounts, beginning balance	5,818	5,818
One-time adjustment	5,818	5,818
Write-Offs	(447)	(447)
Bad Debt Expense	28	151
Notes receivable, Allowance for doubtful accounts, ending balance	$ 6,237	$ 5,823
Elevated risk notes receivable | Cumulative Impact from Adopting ASC 326 Guidance
Notes receivable
One-time adjustment				$ 291