Fair Value Measurements - Reconciliation of Assets and Liabilities Measured Using Significant Unobservable Inputs (Details) $ in Thousands	12 Months Ended
	Sep. 30, 2017 USD ($)
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Total, balance at beginning of period	$ 6,319
Total, change in fair value	(231)
Total, settlements	(6,088)
Total, balance at end of period	0
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance at beginning of period	500
Change in fair value	0
Settlements	(500)
Balance at end of period	0
Convertible Debt Securities
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance at beginning of period	5,774
Change in fair value	(194)
Settlements	(5,580)
Balance at end of period	0
Warrants
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance at beginning of period	45
Change in fair value	(37)
Settlements	(8)
Balance at end of period	$ 0