Condensed Statement of Comprehensive Income (USD $) In Thousands, unless otherwise specified	3 Months Ended
Dec. 31, 2014	Dec. 31, 2013
Statement of Comprehensive Income [Abstract]
Consolidated net income	$ 3,236us-gaap_ProfitLoss	$ 5,446us-gaap_ProfitLoss
Change in unrealized loss on investments:
Changes arising during current period, net of tax benefit of $0 and $251, respectively	0	(349)
Reclassification for gain included in net income, net of tax expense of $0 and $1,373, respectively	0	(2,296)
Change in unrealized loss on investments:	0	(2,645)
Change in cumulative translation adjustment:
Changes arising during current period	(6,504)	(1,222)
Change in retirement plan actuarial losses:
Reclassification for gain included in net income, net of tax expense (benefit) of $0 for the three months ended December 31, 2014 and 2013	29	27
Change in retirement plan transition obligation:
Reclassification for gain included in net income, net of tax expense (benefit) of $0 for the three months ended December 31, 2014 and 2013	(15)	(15)
Other comprehensive loss	(6,490)	(3,855)
Comprehensive income (loss)	(3,254)	1,591
Comprehensive income attributable to noncontrolling interest	(50)	(11)
Comprehensive income (loss) attributable to ISSI	$ (3,304)us-gaap_ComprehensiveIncomeNetOfTax	$ 1,580us-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, before 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 and reclassification adjustments, of appreciation (loss) in value of unsold available-for-sale securities. Excludes amounts related to other than temporary impairment (OTTI) loss.

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Amount after tax and reclassification adjustments of other comprehensive income (loss).

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Amount after tax of reclassification adjustment from accumulated other comprehensive income for unrealized gain (loss) realized upon the sale of available-for-sale securities.

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

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The consolidated profit or loss for the period, net of income taxes, including the portion attributable to the noncontrolling interest.

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