Fair Value Measurements - Carrying Amount and Clarification of Assets and Liabilities (Details) - USD ($) $ in Thousands	Sep. 30, 2017	Sep. 30, 2016
Accounts, Notes, Loans and Financing Receivable [Line Items]
Discount on receivable	$ 100
Guarantee liability	0	$ (1,258)
Notes receivable, net (including accreted deferred compensation of $0.1 million)
Accounts, Notes, Loans and Financing Receivable [Line Items]
Guarantee asset	60,975	83,065
Maximum Exposure to Loss	60,975	83,065
Prepaid expenses and other current assets
Accounts, Notes, Loans and Financing Receivable [Line Items]
Guarantee asset	0	1,209
Maximum Exposure to Loss	0	0
Accounts payable, accrued expenses and other current liabilities
Accounts, Notes, Loans and Financing Receivable [Line Items]
Guarantee liability	0	(1,258)
Maximum Exposure to Loss	$ 0	$ 0