Convertible Debentures (Tables)

9 Months Ended

12 Months Ended

Jun. 30, 2013

Sep. 30, 2012

Debt Disclosure [Abstract]

Convertible debenture activity

	Nine months ended June 30,
	2012			2013
Beginning balance:
Gross balance	$	2,493		$	18,328
Less: Discounts		(529	)		(2,440	)
		1,964			15,888
Proceeds:
To convertible debentures, before allocations		14,664			—
Allocated to detachable warrants		(1,660	)		—
Allocated to beneficial conversion feature		(140	)		—
Allocated to conversion option liability		(467	)		—
Interest expense:
PIK interest		865			707
Amortization of debt discount		258			190
Recognition of unamortized debt discount upon conversion		—			2,250
Conversion:
Issuance of 826 common shares		—			(19,035	)
Ending balance:
Gross balance		18,022			—
Less: Discounts		(2,538	)		—
	$	15,484		$	—

	Years ended September 30,
	2010			2011			2012
Beginning balance:
Gross balance	$	9,856		$	19,101		$	2,493
Less: Discounts		(4,442	)		(5,625	)		(529	)
		5,414			13,476			1,964
Proceeds:
To convertible debentures, before allocations		8,419			5,465			14,664
Allocated to detachable warrants		(1,149	)		(629	)		(1,660	)
Allocated to beneficial conversion feature		(186	)		(96	)		(140	)
Allocated to conversion option liability		—			(153	)		(467	)
Interest expense:
PIK interest		827			1,384			1,171
Amortization of debt discount		152			247			355
Recognition of unamortized discount upon conversion (2009 Debentures)		—			4,615			—
Conversion:
Issuance of 1,602 common shares		—			(23,457	)		—
Recognition of unamortized discount upon conversion to additional paid-in-capital (2010 Debentures)		—			1,112			—
Ending balance:
Gross balance		19,101			2,493			18,328
Less: Discounts		(5,625	)		(529	)		(2,440	)
	$	13,476		$	1,964		$	15,888