CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (LOSS) (USD $) In Thousands, unless otherwise specified	3 Months Ended	6 Months Ended
Mar. 31, 2015	Mar. 31, 2014	Mar. 31, 2015	Mar. 31, 2014
Statement Of Income And Comprehensive Income [Abstract]
Net income (loss)	$ (5,182)us-gaap_NetIncomeLoss	$ 10,816us-gaap_NetIncomeLoss	$ (10,627)us-gaap_NetIncomeLoss	$ 34,992us-gaap_NetIncomeLoss
Other comprehensive income (loss):
Change in unrealized gains on available-for-sale securities (net of tax)	23		21
Foreign currency translations adjustments	(1,966)	(942)	(4,618)	(1,039)
Other comprehensive income (loss)	(1,943)	(942)	(4,597)	(1,039)
Total comprehensive income (loss)	$ (7,125)us-gaap_ComprehensiveIncomeNetOfTax	$ 9,874us-gaap_ComprehensiveIncomeNetOfTax	$ (15,224)us-gaap_ComprehensiveIncomeNetOfTax	$ 33,953us-gaap_ComprehensiveIncomeNetOfTax

Amount after tax of increase (decrease) in equity from transactions and other events and circumstances from net income and other comprehensive income, attributable to parent entity. Excludes changes in equity resulting from investments by owners and distributions to owners.

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Amount after tax and reclassification adjustments of gain (loss) on foreign currency translation adjustments, foreign currency transactions designated and effective as economic hedges of a net investment in a foreign entity and intra-entity foreign currency transactions that are of a long-term-investment nature.

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Amount after tax of other comprehensive income (loss) attributable to parent entity.

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Amount after tax, before reclassification adjustments, of unrealized holding gain (loss) on available-for-sale securities.

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