Condensed Consolidated Statements of Cash Flows (USD $) In Thousands, unless otherwise specified	6 Months Ended
Mar. 31, 2015	Mar. 31, 2014
Cash flows from operating activities:
Net income (loss)	$ 59,180us-gaap_NetIncomeLoss	$ (7,486)us-gaap_NetIncomeLoss
Adjustments to reconcile net income (loss) to net cash used in operating activities:
Depreciation, amortization, and accretion expense	1,803	4,163
Stock-based compensation expense	3,760us-gaap_ShareBasedCompensation	2,239us-gaap_ShareBasedCompensation
Deferred income taxes	24,080us-gaap_DeferredIncomeTaxExpenseBenefit	0us-gaap_DeferredIncomeTaxExpenseBenefit
Gain on sale of an investment	0us-gaap_GainLossOnInvestments	(307)us-gaap_GainLossOnInvestments
Provision adjustments related to doubtful accounts	463us-gaap_ProvisionForDoubtfulAccounts	361us-gaap_ProvisionForDoubtfulAccounts
Provision adjustments related to product warranty	515us-gaap_ProductWarrantyExpense	1,562us-gaap_ProductWarrantyExpense
Change in fair value of financial instruments	(122)us-gaap_UnrealizedGainLossOnDerivatives	71us-gaap_UnrealizedGainLossOnDerivatives
Gain from change in estimate on ARO obligation	(845)	0
Reclassification of foreign currency translation adjustment	(744)	0
Net loss on disposal of equipment	237us-gaap_GainLossOnDispositionOfAssets	0us-gaap_GainLossOnDispositionOfAssets
Settlement of customer related warranty claim	(280)	0
Total non-cash adjustments	(60,149)	8,089
Changes in operating assets and liabilities:
Accounts receivable	3,859	4,003
Inventory	(1,541)us-gaap_IncreaseDecreaseInInventories	3,526us-gaap_IncreaseDecreaseInInventories
Other assets	(913)	2,496
Accounts payable	(3,151)	(630)
Accrued expenses and other current liabilities	(3,012)	(2,698)
Total change in operating assets and liabilities	(4,758)	6,697
Net cash (used in) provided by operating activities	(5,727)	7,300
Cash flows from investing activities:
Cash proceeds from sale of investment	0us-gaap_GainLossOnSaleOfInvestments	307us-gaap_GainLossOnSaleOfInvestments
Purchase of equipment	(1,150)	(1,039)
Decrease (increase) in restricted cash	1,314	(1,178)
Proceeds from disposal of property, plant and equipment	50	0
Net cash provided by (used in) investing activities	151,714	(1,910)
Cash flows from financing activities:
Payments on credit facilities	(26,518)	(4,106)
Proceeds from stock plans	834us-gaap_ProceedsFromStockPlans	659us-gaap_ProceedsFromStockPlans
Net cash used in financing activities	(25,684)	(3,447)
Effect of exchange rate changes on foreign currency	(25)	128
Net increase in cash and cash equivalents	120,278	2,071
Cash and cash equivalents at beginning of period	20,687	16,104
Cash and cash equivalents at end of period	140,965	18,175
SUPPLEMENTAL DISCLOSURE OF CASH FLOW INFORMATION
Cash paid during the period for interest	139us-gaap_InterestPaid	272us-gaap_InterestPaid
Cash paid during the period for income taxes	25us-gaap_IncomeTaxesPaid	4us-gaap_IncomeTaxesPaid
Sale of Digital Products assets to NeoPhotonics for note receivable	15,482	0
Photovoltaics
Adjustments to reconcile net income (loss) to net cash used in operating activities:
Gain (loss) on disposal of discontinued operation, net of tax	(87,022)	0
Cash flows from investing activities:
Proceeds from sale of business	150,000	0
Digital Products Business
Adjustments to reconcile net income (loss) to net cash used in operating activities:
Gain (loss) on disposal of discontinued operation, net of tax	(1,994)	0
Cash flows from investing activities:
Proceeds from sale of business	$ 1,500	$ 0

Asset Retirement Obligation, Gain (Loss) from Revision of Estimates

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Foreign Currency Transaction Gain (Loss) Reclassified to Earnings

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Amount of currency on hand as well as demand deposits with banks or financial institutions. Includes other kinds of accounts that have the general characteristics of demand deposits. Also includes short-term, highly liquid investments that are both readily convertible to known amounts of cash and so near their maturity that they present insignificant risk of changes in value because of changes in interest rates. Excludes cash and cash equivalents within disposal group and discontinued operation.

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