Integrated Silicon Solution (ISSI) 10-Q 31 Jul 15 2015 Q3 Quarterly report Financial data

Document and Entity Information

Document and Entity Information - shares	9 Months Ended
	Jun. 30, 2015	Jul. 24, 2015
Document and Entity Information [Abstract]
Entity Registrant Name	INTEGRATED SILICON SOLUTION INC
Entity Central Index Key	854,701
Current Fiscal Year End Date	--09-30
Entity Filer Category	Accelerated Filer
Document Type	10-Q
Document Period End Date	Jun. 30, 2015
Document Fiscal Year Focus	2,015
Document Fiscal Period Focus	Q3
Amendment Flag	false
Entity Common Stock, Shares Outstanding		32,262,717

Condensed Consolidated Statemen

Condensed Consolidated Statements of Income - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Income Statement [Abstract]
Net sales	$ 81,240	$ 84,834	$ 242,254	$ 244,825
Cost of sales	53,936	55,538	157,757	162,250
Gross profit	27,304	29,296	84,497	82,575
Operating expenses:
Research and development	11,777	10,978	36,448	32,363
Selling, general and administrative	16,179	11,942	43,253	34,845
Total operating expenses	27,956	22,920	79,701	67,208
Operating income (loss)	(652)	6,376	4,796	15,367
Interest and other income (expense), net	213	99	740	905
Gain on sale of investments	0	2,140	0	11,300
Income (loss) before income taxes	(439)	8,615	5,536	27,572
Provision (benefit) for income taxes	(461)	2,388	1,147	6,941
Consolidated net income	22	6,227	4,389	20,631
Net income attributable to noncontrolling interests	(6)	(41)	(71)	(198)
Net income attributable to ISSI	$ 16	$ 6,186	$ 4,318	$ 20,433
Basic net income per share (in dollars per share)	$ 0	$ 0.20	$ 0.14	$ 0.69
Shares used in basic per share calculation	31,950	30,312	31,495	29,816
Diluted net income per share (in dollars per share)	$ 0	$ 0.19	$ 0.13	$ 0.65
Shares used in diluted per share calculation	33,852	31,963	33,300	31,337

Condensed Consolidated Stateme3

Condensed Consolidated Statements of Comprehensive Income - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Statement of Comprehensive Income [Abstract]
Consolidated net income	$ 22	$ 6,227	$ 4,389	$ 20,631
Change in unrealized loss on investments:
Changes arising during current period, net of tax benefit of $0, $0, $0 and $251, respectively	0	0	0	(349)
Reclassification for gain included in net income, net of tax expense of $0, $592, $0 and $3,589, respectively	0	(1,024)	0	(6,029)
Change in unrealized loss on investments:	0	(1,024)	0	(6,378)
Change in cumulative translation adjustment:
Changes arising during current period	1,784	2,989	(3,171)	(1,020)
Change in retirement plan actuarial losses:
Reclassification for gain included in net income, net of tax expense (benefit) of $0 for the three and nine months ended June 30, 2015 and 2014	29	27	87	82
Change in retirement plan transition obligation:
Reclassification for gain included in net income, net of tax expense (benefit) of $0 for the three and nine months ended June 30, 2015 and 2014	(15)	(15)	(44)	(45)
Other comprehensive income (loss)	1,798	1,977	(3,128)	(7,361)
Comprehensive income	1,820	8,204	1,261	13,270
Comprehensive income attributable to noncontrolling interest	(6)	(41)	(71)	(198)
Comprehensive income attributable to ISSI	$ 1,814	$ 8,163	$ 1,190	$ 13,072

Condensed Consolidated Stateme4

Condensed Consolidated Statements of Comprehensive Income (Parenthetical) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Statement of Comprehensive Income [Abstract]
Unrealized gain (loss) on investments, Changes arising during current period, tax	$ 0	$ 0	$ 0	$ 251
Unrealized gain (loss) on investments, Reclassification for gain included in net income, tax	0	592	0	3,589
Retirement plan actuarial losses, Reclassification for gain included in net income, tax	0	0	0	0
Retirement plan transition obligation, Reclassification for gain included in net income, tax	$ 0	$ 0	$ 0	$ 0

Condensed Consolidated Balance

Condensed Consolidated Balance Sheets - USD ($) $ in Thousands	Jun. 30, 2015	Sep. 30, 2014	[1]
Current assets:
Cash and cash equivalents	$ 97,474	$ 137,534
Restricted cash	19,170	1,000
Short-term investments	1,447	1,477
Accounts receivable, net	51,107	50,458
Inventories	87,441	85,093
Deferred tax assets	1,898	1,868
Other current assets	28,279	17,033
Total current assets	286,816	294,463
Property, equipment and leasehold improvements, net	58,046	58,847
Purchased intangible assets, net	4,051	5,093
Goodwill	9,178	9,178
Deferred tax assets	8,768	8,392
Other assets	53,845	24,369
Total assets	420,704	400,342
Current liabilities:
Accounts payable	62,377	54,554
Accrued compensation and benefits	12,540	9,875
Accrued expenses	12,517	11,365
Current portion of long-term debt	195	195
Total current liabilities	87,629	75,989
Long-term debt	4,193	4,339
Other long-term liabilities	5,299	5,456
Total liabilities	$ 97,121	$ 85,784
Commitments and contingencies
Stockholders’ equity:
Common stock	$ 3	$ 3
Additional paid-in capital	378,009	364,587
Accumulated deficit	(52,416)	(51,076)
Accumulated other comprehensive loss	(4,172)	(1,044)
Total ISSI stockholders’ equity	321,424	312,470
Noncontrolling interest	2,159	2,088
Total stockholders’ equity	323,583	314,558
Total liabilities and stockholders’ equity	$ 420,704	$ 400,342
[1]	Derived from audited financial statements.

Condensed Consolidated Stateme6

Condensed Consolidated Statements of Cash Flows - USD ($) $ in Thousands	9 Months Ended
	Jun. 30, 2015		Jun. 30, 2014
Cash flows from operating activities
Consolidated net income	$ 4,389		$ 20,631
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	6,574		5,885
Stock-based compensation	3,959		4,585
Excess tax loss (benefit) from share-based compensation	395		(2,567)
Tax loss associated with employee stock plans	(395)		0
Amortization of intangibles	1,042		1,186
Gain on sale of investments	0		(11,300)
Equity in net loss of affiliate	78		215
Net foreign currency transaction gains	(162)		(405)
Deferred tax assets	(650)		1,736
Other non-cash items	61		(35)
Net effect of changes in current and other assets and current liabilities	(6,787)		(14,231)
Net cash provided by operating activities	8,504		5,700
Cash flows from investing activities
Acquisition of property and equipment	(6,353)		(9,928)
Acquisition of noncontrolling interest in consolidated subsidiary	0		(199)
Investment in Powerchip Leased Assets	(20,574)		0
Payment of license fees	(6,180)		(7,098)
Increase in restricted cash	(18,170)		(1,000)
Purchases of available-for-sale securities	(1,272)		(1,316)
Sales of available-for-sale securities	1,313		22,143
Net cash (used in) provided by investing activities	(51,236)		2,602
Cash flows from financing activities
Repurchases and retirement of common stock	(513)		(350)
Proceeds from issuance of stock through compensation plans	10,371		9,569
Dividends Paid	(5,658)		0
Excess tax (loss) benefit from share-based compensation	(395)		2,567
Principal payments of long-term obligations	(146)		(146)
Net cash provided by financing activities	3,659		11,640
Effect of exchange rate changes on cash and cash equivalents	(987)		(470)
Net (decrease) increase in cash and cash equivalents	(40,060)		19,472
Cash and cash equivalents at beginning of period	137,534	[1]	119,997
Cash and cash equivalents at end of period	$ 97,474		$ 139,469
[1]	Derived from audited financial statements.

Basis of Presentation

Basis of Presentation	9 Months Ended
	Jun. 30, 2015
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Basis of Presentation	Basis of Presentation The accompanying unaudited condensed consolidated financial statements include the accounts of Integrated Silicon Solution, Inc. (the Company or ISSI) and its majority owned subsidiaries, after elimination of all significant intercompany accounts and transactions. These financial statements have been prepared in accordance with accounting principles generally accepted in the United States of America (U.S. GAAP) for interim financial information and with Rule 10-01 of Regulation S-X. Accordingly, they do not include all of the information and footnotes required by accounting principles generally accepted in the United States for complete financial statements. In the opinion of management, all adjustments (which are of a normal, recurring nature) considered necessary for fair presentation have been included. On March 12, 2015, the Company and Uphill Investment Co. (Uphill) entered into a definitive merger agreement (as amended, the Merger Agreement) under which Uphill would acquire all of the Company's outstanding shares for $19.25 per share in cash (the Merger). Subsequent to March 12, the merger agreement was amended several times to increase the purchase price. As a result of the amendment to the Merger Agreement executed on June 22, 2015, the purchase price to be paid by Uphill to the Company’s stockholders is $23.00 per share in cash. The transaction was approved by the stockholders of the Company on June 29, 2015. The closing of the transaction is pending regulatory approvals. As part of the transaction, the Merger Agreement contemplates that, in connection with the closing of the merger, the Company's operations in Taiwan will be restructured or some or all of the Company's Taiwan operations may be sold in order to comply with the requirements of Taiwan laws and regulations. The transaction is currently expected to close in the third calendar quarter of 2015. On September 14, 2012, the Company acquired approximately 94.1% of the outstanding shares of Chingis Technology Corporation (Chingis) and the Company’s financial results reflect accounting for Chingis on a consolidated basis from the date of acquisition. In May 2013, the Company acquired an additional 4.8% of Chingis for approximately $1.6 million . In fiscal 2014, the Company acquired the remaining 1.1% of Chingis for approximately $0.4 million , and at June 30, 2015 , the Company owned 100% of Chingis. The Company’s operating results for the nine months ended June 30, 2015 are not necessarily indicative of the results that may be expected for the fiscal year ending September 30, 2015 or for any other period. The financial statements included herein should be read in conjunction with the Company’s Annual Report on Form 10-K for the fiscal year ended September 30, 2014 .

Use of Estimates

Use of Estimates	9 Months Ended
	Jun. 30, 2015
Accounting Policies [Abstract]
Use of Estimates	Use of Estimates The preparation of financial statements in conformity with U.S. GAAP requires management to make estimates and assumptions that affect the reported amounts of assets, liabilities and the disclosure of contingent assets and liabilities at the date of the financial statements as well as the reported amounts of revenues and expenses during the reporting period. Such estimates include the useful lives of fixed assets, allowances for doubtful accounts and customer returns, valuation allowances for deferred tax assets, inventory write-downs, potential reserves relating to litigation matters, accrued liabilities, and other reserves. The Company bases its estimates and judgments on its historical experience, knowledge of current conditions and its beliefs of what could occur in the future, given available information. Actual results may differ from those estimates, and such differences may be material to the financial statements.

Impact of Recently Issued Accou

Impact of Recently Issued Accounting Pronouncements and Standards	9 Months Ended
	Jun. 30, 2015
Accounting Changes and Error Corrections [Abstract]
Impact of Recently Issued Accounting Pronouncements and Standards	Impact of Recently Issued Accounting Pronouncements and Standards Impact of Recently Adopted Accounting Standards On October 1, 2014, the Company adopted the following accounting standards, which did not have any impact on its consolidated results of operations during such period or its financial condition at the end of such period: Liabilities In February 2013, the Financial Accounting Standards Board (FASB) issued guidance for the recognition, measurement and disclosure of obligations resulting from joint and several liability arrangements for which the total amount of the obligation within the scope of the guidance is fixed at the reporting date. Examples of obligations include debt arrangements, other contractual obligations, settled litigation and judicial rulings. The guidance requires an entity to measure such obligations as the sum of the amount that the reporting entity agreed to pay on the basis of its arrangement among its co-obligors in addition to amounts the reporting entity expects to pay on behalf of its co-obligors. Foreign Currency Matters In March 2013, the FASB issued guidance on when foreign currency translation adjustments should be released to net income. When a parent entity ceases to have a controlling financial interest in a subsidiary or group of assets that is a business within a foreign entity, the parent is required to release any related cumulative translation adjustment into net income. Accordingly, the cumulative translation adjustment should be released into net income only if the sale or transfer results in the complete or substantially complete liquidation of the foreign entity in which the subsidiary or group of assets had resided. Accounting Pronouncements The following issued accounting pronouncements are not yet effective for the Company as of June 30, 2015. Revenue from Contracts with Customers In May 2014, the FASB amended the existing accounting standards for revenue recognition. The new guidance establishes principles for recognizing revenue upon the transfer of promised goods or services to customers, in an amount that reflects the expected consideration received in exchange for those goods or services. The guidance becomes effective for the Company beginning in the first quarter of fiscal 2019. Early adoption is not permitted. The new revenue standard may be applied retrospectively to each prior period presented or retrospectively with the cumulative effect recognized as of the date of adoption. The Company has not yet selected a transition method nor has the Company determined the impact of adopting the new revenue standard on its consolidated financial statements.

Fair Value Measurements

Fair Value Measurements	9 Months Ended
	Jun. 30, 2015
Fair Value Disclosures [Abstract]
Fair Value Measurements	Fair Value Measurements Under FASB guidance, fair value is defined as the price expected to be received from the sale of an asset or paid to transfer a liability in a transaction between market participants at the measurement date. In determining fair value, the Company uses various valuation approaches, including quoted market prices and discounted cash flows. The FASB guidance also establishes a hierarchy for inputs used in measuring fair value that maximizes the use of observable inputs and minimizes the use of unobservable inputs by requiring that the most observable inputs be used when available. Observable inputs are inputs that the market participants would use in pricing the asset or liability developed based on market data obtained from independent sources. Unobservable inputs are inputs that reflect a company’s judgment concerning the assumptions that market participants would use in pricing the asset or liability developed based on the best information available at that time. The fair value hierarchy is broken down into the following three levels based on the reliability of inputs: • Level 1 – Valuations based on quoted prices in active markets for identical instruments that the Company is able to access. Since valuations are based on quoted prices which are readily and regularly available in an active market, valuation of these products can be done without a significant degree of judgment. • Level 2 – Valuations based on quoted prices in active markets for instruments that are similar, or quoted prices in markets that are not active for identical or similar instruments and model-derived valuations in which all significant inputs and significant value drives are observable in active markets. • Level 3 – Valuations based on inputs that are unobservable and significant to the overall fair value measurement. These values are generally determined using pricing models for which the assumptions utilize management’s estimates of market participant assumptions. As of June 30, 2015 and September 30, 2014 , all of the Company’s financial assets utilized Level 1 inputs. As of June 30, 2015 , the Company did not have any liabilities or non-financial assets that are measured at fair value on a recurring basis. Available-for-sale marketable securities consisted of the following: June 30, 2015 Amortized Cost Gross Unrealized Holding Gains Gross Unrealized Holding Losses Fair Value (In thousands) Available-for-sale Level 1: Money market instruments $ 9,327 $ — $ — $ 9,327 Certificates of deposit 13,840 — — 13,840 Total 23,167 — — 23,167 Less: Amounts included in cash and cash equivalents (21,720 ) — — (21,720 ) $ 1,447 $ — $ — $ 1,447 September 30, 2014 Amortized Cost Gross Unrealized Holding Gains Gross Unrealized Holding Losses Fair Value (In thousands) Available-for-sale Level 1: Money market instruments $ 22,519 $ — $ — $ 22,519 Certificates of deposit 20,679 — — 20,679 Total 43,198 — — 43,198 Less: Amounts included in cash, cash equivalents and restricted cash (41,721 ) — — (41,721 ) $ 1,477 $ — $ — $ 1,477 There were no transfers in or out of Level 1 assets during the three months ended June 30, 2015 . As of June 30, 2015 and September 30, 2014 , the Company had cash, cash equivalents, restricted cash and short-term investments in foreign financial institutions of $55.4 million ( $1.6 million of which was in China and subject to exchange control regulations) and $71.9 million , respectively.

Stock-based Compensation

Stock-based Compensation	9 Months Ended
	Jun. 30, 2015
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Stock-based Compensation	Stock-based Compensation Stock-Based Benefit Plans The Company grants stock-based compensation awards under its 2007 Incentive Compensation Plan (the 2007 Plan) which permits the grant of stock options, stock appreciation rights (SARs), restricted stock awards, restricted stock units (RSUs), performance shares and performance units. The Company has outstanding grants under its 2012 Inducement Option Plan (the Inducement Plan) and under prior plans, though no further grants can be made under these plans. At June 30, 2015 , 1,530,000 shares were available for future grant under the 2007 Plan. Options generally vest ratably over a four -year period with a 6 -month or 1 -year cliff vest and then vesting ratably over the remaining period. Options granted prior to October 1, 2005 expire ten years after the date of grant; options granted after October 1, 2005 expire seven years after the date of the grant. RSUs generally vest annually over periods ranging from two years to four years based upon continued employment with the Company. The Company began granting cash-settled SARs in the first quarter of fiscal 2014. The SARs vest ratably over a four -year period with a 6 -month or 1 -year cliff vest and then vest ratably each month over the remaining period based upon continued employment with the Company. The SARs expire seven years after the date of grant. These SARs allow the holder to receive in cash the difference between the SARs' exercise price (which is the closing market price of the Company's common stock on the grant date) and the closing market price of the Company's common stock on the date the holder exercises the SAR. The SARs are recorded as a liability in accrued compensation and benefits in the Company's balance sheet. The Company had an Employee Stock Purchase Plan (ESPP) which permitted eligible employees to purchase shares of the Company’s common stock through payroll deductions. As approved by the Board of Directors, effective August 1, 2010, shares under the ESPP were purchased at a price equal to 85% of the lesser of the fair market value of the Company’s common stock as of the first day or the last day of each six -month offering period. The offering periods under the ESPP commenced on approximately February 1 and August 1 of each year. The ESPP terminated pursuant to its terms on February 2, 2015, therefore at June 30, 2015 , no shares were available for future issuance under the ESPP. Stock-Based Compensation The following table outlines the effects of total stock-based compensation including expense related to SARs. Three Months Ended Nine Months Ended 2015 2014 2015 2014 (In thousands) Stock-based compensation Cost of sales $ 26 $ 50 $ 124 $ 154 Research and development 650 694 2,146 2,119 Selling, general and administrative 1,867 1,017 4,294 3,156 Total stock-based compensation 2,543 1,761 6,564 5,429 Tax effect on stock-based compensation (688 ) (330 ) (1,520 ) (1,018 ) Net effect on net income $ 1,855 $ 1,431 $ 5,044 $ 4,411 Compensation related to SARs included in total stock-based compensation $ 1,374 $ 222 $ 2,605 $ 844 As of June 30, 2015 , there was approximately $7.7 million of total unrecognized stock-based compensation expense related to awards under the Company’s stock-based benefit plans that will be recognized over a weighted-average period of approximately 2.18 years. Future awards will add to this total whereas quarterly amortization and the vesting of existing awards will reduce this total. As of June 30, 2015 , there was approximately $10.5 million of total unrecognized stock-based compensation expense related to SARs that will be recognized over a weighted-average period of approximately 2.86 years. Future SAR grants will add to this total whereas quarterly amortization and the vesting of SARs will reduce this total. In addition, because SARs are settled with cash, the fair value of SARs must be revalued on a quarterly basis which will likely impact the amount of expense in future periods. The Company uses the Black-Scholes option pricing model to estimate the fair value of the options and SARs granted and rights to acquire stock granted under the ESPP. The weighted average estimated fair values of stock option grants and rights granted under the ESPP, as well as the weighted average assumptions used in calculating these values during the three and nine month periods ended June 30, 2015 and 2014 were based on estimates at the date of grant as follows: Three Months Ended Nine Months Ended 2015 2014 2015 2014 Options Weighted-average fair value of grants $ — $ 6.13 $ 4.11 $ 4.70 Expected term in years — 4.42 4.27 4.42 Estimated volatility — % 51 % 38 % 51 % Risk-free interest rate — % 1.21 % 1.25 % 1.04 % Dividend yield — % — % 1.66 % — % ESPP Weighted-average fair value of grants $ — $ — $ — $ 2.66 Expected term in years — — — 0.49 Estimated volatility — % — % — % 27 % Risk-free interest rate — % — % — % 0.41 % Dividend yield — % — % — % — % The Company issues RSUs from time to time. The estimated fair value of RSU awards is calculated based on the market price of the Company’s common stock on the date of grant. The weighted average grant date fair value of RSUs granted in the three and nine months ended June 30, 2015 was $18.70 per share and $13.59 per share, respectively. The weighted average grant date fair value of RSUs granted in the three and nine months ended June 30, 2014 was $14.45 per share and $11.62 per share, respectively. A summary of the Company’s stock option activity and related information for the nine months ended June 30, 2015 follows (number of shares and aggregate intrinsic value are presented in thousands): Number of Shares Weighted-Average Exercise Price Weighted-Average Remaining Contractual Term in Years Aggregate Intrinsic Value Outstanding at September 30, 2014 4,240 $ 8.10 Granted 85 $ 14.83 Exercised (1,190 ) $ 7.67 $ 11,883 Cancelled/Expired (47 ) $ 10.84 Outstanding at June 30, 2015 3,088 $ 8.40 3.40 $ 42,421 Exercisable at June 30, 2015 2,192 $ 7.50 2.85 $ 32,077 Vested and expected to vest after June 30, 2015 3,057 $ 8.38 3.39 $ 42,082 A summary of the Company’s RSU activity and related information for the nine months ended June 30, 2015 under the 2007 Plan follows (number of shares and aggregate intrinsic value are presented in thousands): Number of Shares Weighted-Average Grant Date Fair Value Aggregate Intrinsic Value Outstanding at September 30, 2014 262 $ 9.91 Granted 230 $ 13.59 Vested (110 ) $ 9.43 $ 1,546 Forfeited (3 ) $ 13.22 Outstanding at June 30, 2015 379 $ 12.26 $ 8,385 A summary of the Company’s SAR activity and related information for the nine months ended June 30, 2015 under the 2007 Plan follows (number of shares and aggregate intrinsic value are presented in thousands): Number of Shares Weighted-Average Exercise Price Weighted-Average Remaining Contractual Term in Years Aggregate Intrinsic Value Outstanding at September 30, 2014 747 $ 10.96 Granted 682 $ 13.55 Exercised (107 ) $ 13.55 $ 895 Cancelled/Expired (27 ) $ 12.17 Outstanding at June 30, 2015 1,295 $ 12.25 5.85 $ 12,811 Exercisable at June 30, 2015 247 $ 11.36 5.51 $ 2,662

Concentrations

Concentrations	9 Months Ended
	Jun. 30, 2015
Risks and Uncertainties [Abstract]
Concentrations	Concentrations In the three and nine months ended June 30, 2015 , revenue from the Company's largest distributor accounted for approximately 18% and 16% , respectively, of the Company's total net sales. In the three and nine months ended June 30, 2015 , revenue from the Company's second largest distributor accounted for approximately 11% and 13% , respectively, of the Company's total net sales. In the three and nine months ended June 30, 2014 , revenue from the Company's largest distributor accounted for approximately 20% and 18% , respectively, of the Company's total net sales. In the three and nine months ended June 30, 2014 , revenue from the Company's second largest distributor accounted for approximately 12% and 13% , respectively, of the Company's total net sales.

Inventories

Inventories	9 Months Ended
	Jun. 30, 2015
Inventory Disclosure [Abstract]
Inventories	Inventories The following is a summary of inventories by major category: June 30, September 30, (In thousands) Purchased components $ 25,001 $ 21,677 Work-in-process 22,959 27,058 Finished goods 39,481 36,358 $ 87,441 $ 85,093 During the three and nine months ended June 30, 2015 , the Company recorded inventory write-downs of $1.5 million and $4.7 million , respectively. During the three and nine months ended June 30, 2014 , the Company recorded inventory write-downs of $2.1 million and $4.3 million , respectively. The inventory write-downs were predominantly for excess and obsolescence and lower of cost or market issues on certain of the Company's products.

Other Current Assets and Other

Other Current Assets and Other Assets	9 Months Ended
	Jun. 30, 2015
Other Assets [Abstract]
Other Current Assets and Other Assets	Other Current Assets and Other Assets Other current assets consisted of the following: June 30, September 30, (In thousands) Prepayments for Powerchip lease related assets $ 11,173 $ — Other current assets 17,106 17,033 $ 28,279 $ 17,033 Other assets consisted of the following: June 30, September 30, (In thousands) Restricted assets $ 651 $ 499 Other investment 1,358 1,436 Nanya private placement shares 10,428 10,645 Technology licenses, net 15,339 10,644 Powerchip lease related assets 24,904 — Other 1,165 1,145 $ 53,845 $ 24,369 The Company has various deposits including deposits with suppliers for purchase guarantees and for customs clearance. These deposits are included in restricted assets. The Company accounts for the private placement shares it acquired in Nanya on the cost-basis as these securities are restricted and the restrictions do not terminate within one year of the reporting date. From time to time, the Company licenses patents or other intellectual property rights from third parties. The technology licenses are being amortized over their estimated useful lives ranging from three to fifteen years. On April 20, 2015, the Company entered into Equipment Lease Agreements ( Lease Agreements) with Powerchip Technology Corporation (Powerchip). Under the Lease Agreements, the Company will purchase and then lease up to an aggregate of $73.5 million in semiconductor manufacturing equipment to Powerchip whereby Powerchip will acquire ownership of the equipment at the end of the lease period, and the Company will obtain access to certain manufacturing capacity and technology at Powerchip. As of June 30, 2015 , the Company had purchased $24.9 million of equipment related to the Powerchip lease. The Lease Agreements provide for a term of approximately six years, each ending December 31, 2021. Beginning in 2019 and continuing through 2021, Powerchip will make quarterly payments to the Company in an aggregate amount of approximately $82.1 million (the Quarterly Payments). Until such time as all Quarterly Payments have been made, the Company shall own, and continue to own, all equipment subject to the Lease Agreements. In addition to making the Quarterly Payments, Powerchip shall provide the Company with manufacturing capacity to produce a specified number of wafers each month beginning in 2015 through 2021. The Company has an option to renew such manufacturing arrangement for an additional three years. In March 2012, the Company made an equity investment of $2.0 million in a private technology company headquartered in Hong Kong. At June 30, 2015, the Company's ownership interest in such company was approximately 25% . This investment is accounted for under the equity method and the Company's results include its percentage share of such company's results of operations in interest and other income (expense), net.

Purchased Intangible Assets

Purchased Intangible Assets	9 Months Ended
	Jun. 30, 2015
Goodwill and Intangible Assets Disclosure [Abstract]
Purchased Intangible Assets	Purchased Intangible Assets The following tables present details of the Company’s total purchased intangible assets: Gross Accumulated Amortization Net (In thousands) June 30, 2015 Developed technology $ 5,330 $ 3,096 $ 2,234 Customer relationships 3,340 1,554 1,786 Other 450 419 31 Total $ 9,120 $ 5,069 $ 4,051 September 30, 2014 Developed technology $ 5,330 $ 2,584 $ 2,746 Customer relationships 3,340 1,137 2,203 Other 450 306 144 Total $ 9,120 $ 4,027 $ 5,093 The following table presents details of the amortization expense of purchased intangible assets as reported in the consolidated statements of income: Three Months Ended Nine Months Ended 2015 2014 2015 2014 (In thousands) Reported as: Cost of sales $ 171 $ 191 $ 512 $ 656 Operating expenses 177 177 530 530 Total $ 348 $ 368 $ 1,042 $ 1,186 The following table presents the estimated future amortization expense of the Company’s purchased intangible assets at June 30, 2015 (in thousands). The weighted-average remaining amortization period for developed technology, customer relationships and other intangibles is 3.29 years, 3.21 years and 0.21 years, respectively. If the Company acquires additional purchased intangible assets in the future, its future amortization may be increased by those assets. Fiscal year Remainder of 2015 $ 341 2016 1,238 2017 1,238 2018 1,195 2019 39 Thereafter — Total $ 4,051

Borrowings

Borrowings	9 Months Ended
	Jun. 30, 2015
Debt Disclosure [Abstract]
Borrowings	Borrowings In December 2012, the Company obtained a bank loan in the amount of $4.9 million (the Loan), to partially finance the $6.5 million purchase price of approximately 2.85 acres of land and a 55,612 square foot building located at 1623 Buckeye Drive, Milpitas, California for its corporate headquarters. The Loan has a maturity date of November 30, 2017 and is secured by the property and an assignment of all leases and rents relating to the property. The Loan is subject to customary events of default, including defaults in the payment of principal and interest. The Loan bears an interest rate of one percent above LIBOR adjusted on a monthly basis. The interest rate on the Loan was 1.25% at June 30, 2015. Principal payments due under the Loan are as follows (in thousands): Fiscal year Remainder of 2015 $ 49 2016 195 2017 195 2018 3,949 2019 — Thereafter — Total $ 4,388

Accumulated Other Comprehensive

Accumulated Other Comprehensive Loss	9 Months Ended
	Jun. 30, 2015
Stockholders' Equity Note [Abstract]
Accumulated Other Comprehensive Loss	Accumulated Other Comprehensive Loss The components of accumulated other comprehensive loss, net of tax, were as follows (in thousands): June 30, September 30, Accumulated foreign currency translation adjustments $ (2,120 ) $ 1,051 Accumulated net retirement plan transition asset (liability) (net of tax of $124 and $124, respectively) (36 ) 8 Accumulated net retirement plan actuarial losses (net of tax of $477 and $477, respectively) (2,016 ) (2,103 ) Total accumulated other comprehensive loss $ (4,172 ) $ (1,044 ) The significant amounts reclassified out of accumulated other comprehensive loss into the consolidated condensed statements of income, with presentation location, during the three and nine months ended June 30, 2015 and June 30, 2014 were as follows: Three Months Ended Nine Months Ended 2015 2014 2015 2014 (In thousands) Comprehensive Income Components Amount Reclassified from Accumulated Other Comprehensive Loss Location Unrealized holding gains on available-for -sale investments $ — $ 1,616 $ — $ 9,618 Gain on the sale of investments — (592 ) — (3,589 ) Provision for income taxes $ — $ 1,024 $ — $ 6,029

Income Taxes

Income Taxes	9 Months Ended
	Jun. 30, 2015
Income Tax Disclosure [Abstract]
Income Taxes	Income Taxes The income tax provision includes U.S. federal, state and local, and foreign income taxes and is based on the application of a forecasted annual income tax rate applied to the current quarter's year-to-date pre-tax income for fiscal 2015 . In determining the estimated annual effective income tax rate, the Company analyzes various factors, including projections of the Company's annual earnings, taxing jurisdictions in which the earnings will be generated, the impact of state and local income taxes, the Company's ability to use tax credits and net operating loss carryforwards, and available tax planning alternatives. Discrete items, including the effect of changes in tax laws, tax rates, and certain circumstances with respect to valuation allowances or other unusual or non-recurring tax adjustments are reflected in the period in which they occur as an addition to, or reduction from, the income tax provision, rather than being included in the estimated annual effective income tax rate. For the three and nine months ended June 30, 2015 , the Company recorded income tax expense (benefit) of $(0.5) million and $1.1 million , respectively, that represents an effective tax rate of approximately 104% and 21% , respectively. The differences between the recorded provision for income taxes and the tax provision, based on the federal statutory rate of 35% , were primarily attributable to the differential in foreign tax rates, non-deductible stock-based compensation expense and certain foreign losses not benefited. For the three and nine months ended June 30, 2014 , the Company recorded income tax expense of $2.4 million and $6.9 million , respectively, that represents an effective tax rate of approximately 28% and 25% , respectively. The difference between the recorded provision for income taxes and the tax provision, based on the federal statutory rate of 35% , was primarily attributable to the differential in foreign tax rates and non-deductible stock-based compensation expense. As of June 30, 2015 , the Company had unrecognized tax positions that would impact its effective tax rate, if realized.

Per Share Data

Per Share Data	9 Months Ended
	Jun. 30, 2015
Earnings Per Share [Abstract]
Per Share Data	Per Share Data The following table sets forth the computation of basic and diluted net income per share (in thousands, except per share amounts): Three Months Ended Nine Months Ended 2015 2014 2015 2014 Numerator for basic and diluted net income per share: Net income attributable to ISSI $ 16 $ 6,186 $ 4,318 $ 20,433 Denominator for basic net income per share: Weighted average common shares outstanding 31,950 30,312 31,495 29,816 Dilutive stock options and awards 1,902 1,651 1,805 1,521 Denominator for diluted net income per share 33,852 31,963 33,300 31,337 Basic net income per share $ — $ 0.20 $ 0.14 $ 0.69 Diluted net income per share $ — $ 0.19 $ 0.13 $ 0.65 For the three months and nine months ended June 30, 2015 , stock options and awards for 46,000 shares and 100,000 shares, respectively, were excluded from diluted earnings per share by the application of the treasury stock method. For the three months and nine months ended June 30, 2014 , stock options and awards for 686,000 shares and 1,070,000 shares, respectively, were excluded from diluted earnings per share by the application of the treasury stock method.

Common Stock Repurchase Program

Common Stock Repurchase Program	9 Months Ended
	Jun. 30, 2015
Common Stock Repurchase Program [Abstract]
Common Stock Repurchase Program	Common Stock Repurchase Program In the nine month period ended June 30, 2015 , the Company did not repurchase any shares of its common stock in the open market. As of June 30, 2015 , the Company had repurchased and retired an aggregate of 14,179,711 shares of common stock at a cost of approximately $88.5 million since September 2007. As of June 30, 2015 , $19.8 million remained available under the Company's existing share repurchase authorization. However, under the terms of the Merger Agreement, the Company is currently prohibited from repurchasing any shares of its common stock. The Company issues RSUs as part of its equity incentive plan. For a portion of the RSUs granted, the number of shares issued on the date the RSUs vest is net of the statutory withholding requirements that the Company pays on behalf of its employees. During the nine months ended June 30, 2015 , the Company withheld 36,891 shares to satisfy approximately $0.5 million of employee tax obligations. Although the shares withheld are not issued, they are treated as common stock repurchases for accounting purposes, as they reduce the number of shares that would have been issued upon vesting.

Commitments and Contingencies

Commitments and Contingencies	9 Months Ended
	Jun. 30, 2015
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	Commitments and Contingencies Legal Matters In the semiconductor industry, it is not unusual for companies to receive notices alleging infringement of patents or other intellectual property rights of others. The Company has been, and from time to time expects to be, notified of claims that it may be infringing patents, maskwork rights or copyrights owned by third parties. If it appears necessary or desirable, the Company may seek licenses under patents that it is alleged to be infringing. Although patent holders commonly offer such licenses, licenses may not be offered and the terms of any offered licenses may not be acceptable to the Company. The failure to obtain a license under a key patent or intellectual property right from a third party for technology used by the Company could cause it to incur substantial liabilities and to suspend the manufacture of the products utilizing the invention or to attempt to develop non-infringing products, any of which could materially and adversely affect the Company’s business and operating results. Furthermore, there can be no assurance that the Company will not become involved in protracted litigation regarding its alleged infringement of third party intellectual property rights or litigation to assert and protect its patents or other intellectual property rights. Any litigation relating to patent infringement or other intellectual property matters could result in substantial cost and diversion of the Company’s resources. GSI Technology Inc. v. Integrated Silicon Solution, Inc., et al. On October 2, 2013, GSI Technology Inc. (GSI) filed a Second Amended Complaint in a lawsuit filed earlier in 2013 solely against defendant United Memories, Inc. in the United States District Court for the Northern District of California. GSI named the Company as a new, second defendant in the Second Amended Complaint. On April 18, 2014, the Court granted the Company's motion to dismiss that complaint in part, leaving claims against the Company for Unfair Competition under California Business & Professions Code 17200, misappropriation of trade secrets, and intentional interference with prospective economic advantage. In the remaining portion of the complaint, GSI alleged that the Company acted together with United Memories, Inc. to harm GSI in connection with a bid requested by Cisco Systems, Inc. and misappropriated alleged GSI trade secrets. GSI seeks damages and injunctive relief. The Company filed an answer on June 2, 2014 and asserted a declaratory relief counterclaim against GSI. Before the Company was named as a defendant, the Court denied motions by GSI against United Memories, Inc. for temporary and preliminary injunctive relief. The Court issued a revised case management order on January 7, 2015 with a scheduled trial date of October 26, 2015. Motions for summary judgment, including a motion filed by the Company, were heard on June 30, 2015 and are currently pending before the Court. The Company believes it has meritorious defenses to the claims alleged by GSI and intends to defend this suit vigorously. However, there can be no assurance as to the outcome of this matter or any future litigation. Legal Proceedings Regarding our Pending Acquisition Beginning on April 1, 2015, three purported stockholder class action complaints were filed in the Superior Court of the State of California in the County of Santa Clara on behalf of a putative class of ISSI stockholders and naming as defendants ISSI’s Board of Directors and Uphill: Richard Wilson III v. Jimmy S.M. Lee, et al. , Case No. 1-15-CV-278815 (filed April 1, 2015); Matthew Sciabacucchi v. Jimmy S.M. Lee, et al. , Case No. 1-15-CV-278812 (filed April 1, 2015); and Kathy Guerra v. Scott D. Howarth, et al. , Case No. 1-15-CV-279142 (filed April 8, 2015) (the “ Guerra Action”). On May 5, 2015, the actions were consolidated to form In re Integrated Silicon Solution, Inc. Stockholder Litigation , Lead Case No. 1-15-cv-278812, and plaintiffs designated the complaint filed in the Guerra Action as the operative complaint. The operative complaint generally alleges that, in connection with the proposed acquisition of ISSI by Uphill, the ISSI directors breached their fiduciary duties owed to ISSI’s stockholders by, among other things, purportedly failing to take steps to maximize the value of ISSI to ISSI’s stockholders and agreeing to allegedly preclusive deal protection devices in the Merger Agreement. The operative complaint also alleges that the ISSI directors breached their fiduciary duties by allegedly failing to disclose material information to ISSI stockholders. The operative complaint further generally alleges that Uphill aided and abetted the ISSI directors in the alleged breaches of their fiduciary duties. The operative complaint seeks, among other things, an order enjoining the defendants from consummating the proposed transaction, or alternatively, in the event that the proposed transaction is consummated, an order rescinding it. A case management conference is currently scheduled for October 2, 2015. Other Legal Proceedings In the ordinary course of its business, the Company has been involved in a limited number of other legal actions, both as plaintiff and defendant, and could incur uninsured liability in any one or more of them. Although the outcome of these actions is not presently determinable, the Company believes that the ultimate resolution of these matters will not have a material adverse effect on its financial position, cash flows or results of operations. However, no assurances can be given with respect to the extent or outcome of any such litigation in the future. Commitments to Wafer Fabrication Facilities and Contract Manufacturers The Company issues purchase orders for wafers to various wafer foundries. These purchase orders are generally considered to be cancelable. However, to the degree that the wafers have entered into work-in-process at the foundry, as a matter of practice, it becomes increasingly difficult to cancel the purchase order. As of June 30, 2015 , the Company had approximately $20.9 million of purchase orders for which the related wafers had been entered into wafer work-in-process (i.e., manufacturing had begun).

Geographic and Segment Informat

Geographic and Segment Information	9 Months Ended
	Jun. 30, 2015
Segment Reporting [Abstract]
Geographic and Segment Information	Geographic and Segment Information The Company has one operating segment, which is to design, develop, and market high-performance SRAM, DRAM, and other semiconductor products. The following table summarizes the Company’s operations in different geographic areas: Three Months Ended Nine Months Ended 2015 2014 2015 2014 (In thousands) Net sales United States $ 10,148 $ 9,571 $ 30,254 $ 28,449 China 8,392 9,838 27,149 32,689 Hong Kong 15,049 16,456 43,444 45,499 Japan 7,753 5,916 20,371 16,569 Korea 3,289 4,000 11,112 10,544 Taiwan 10,416 12,344 32,186 35,099 Other Asia Pacific countries 5,332 6,435 16,858 18,390 Europe 20,608 19,587 60,138 56,207 Other 253 687 742 1,379 Total net sales $ 81,240 $ 84,834 $ 242,254 $ 244,825 June 30, September 30, (In thousands) Long-lived assets United States $ 11,171 $ 11,174 Hong Kong 10 14 China 13,956 12,908 Taiwan 32,909 34,751 $ 58,046 $ 58,847 Revenues are attributed to countries based on the customers' ship-to location. Long-lived assets by geographic area are those assets used in the Company’s operations in each area.

Related Party Transactions

Related Party Transactions	9 Months Ended
	Jun. 30, 2015
Related Party Transactions [Abstract]
Related Party Transactions	Related Party Transactions The Company sells semiconductor products to Chrontel International Ltd. (Chrontel). Jimmy S.M. Lee, the Company’s Executive Chairman, has been a director of Chrontel since July 1995. Sales to Chrontel were $0 and $144,000 during the three and nine months ended June 30, 2015 , respectively. Sales to Chrontel were $80,000 and $162,000 during the three months and nine months ended June 30, 2014 , respectively. Accounts receivable from Chrontel were approximately $0 and $59,000 at June 30, 2015 and September 30, 2014 , respectively.

Basis of Presentation (Policies

Basis of Presentation (Policies)	9 Months Ended
	Jun. 30, 2015
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Basis of Presentation	The accompanying unaudited condensed consolidated financial statements include the accounts of Integrated Silicon Solution, Inc. (the Company or ISSI) and its majority owned subsidiaries, after elimination of all significant intercompany accounts and transactions. These financial statements have been prepared in accordance with accounting principles generally accepted in the United States of America (U.S. GAAP) for interim financial information and with Rule 10-01 of Regulation S-X. Accordingly, they do not include all of the information and footnotes required by accounting principles generally accepted in the United States for complete financial statements. In the opinion of management, all adjustments (which are of a normal, recurring nature) considered necessary for fair presentation have been included.
Impact of Recently Adopted Accounting Standards and Accounting Pronouncements	Impact of Recently Adopted Accounting Standards On October 1, 2014, the Company adopted the following accounting standards, which did not have any impact on its consolidated results of operations during such period or its financial condition at the end of such period: Liabilities In February 2013, the Financial Accounting Standards Board (FASB) issued guidance for the recognition, measurement and disclosure of obligations resulting from joint and several liability arrangements for which the total amount of the obligation within the scope of the guidance is fixed at the reporting date. Examples of obligations include debt arrangements, other contractual obligations, settled litigation and judicial rulings. The guidance requires an entity to measure such obligations as the sum of the amount that the reporting entity agreed to pay on the basis of its arrangement among its co-obligors in addition to amounts the reporting entity expects to pay on behalf of its co-obligors. Foreign Currency Matters In March 2013, the FASB issued guidance on when foreign currency translation adjustments should be released to net income. When a parent entity ceases to have a controlling financial interest in a subsidiary or group of assets that is a business within a foreign entity, the parent is required to release any related cumulative translation adjustment into net income. Accordingly, the cumulative translation adjustment should be released into net income only if the sale or transfer results in the complete or substantially complete liquidation of the foreign entity in which the subsidiary or group of assets had resided. Accounting Pronouncements The following issued accounting pronouncements are not yet effective for the Company as of June 30, 2015. Revenue from Contracts with Customers In May 2014, the FASB amended the existing accounting standards for revenue recognition. The new guidance establishes principles for recognizing revenue upon the transfer of promised goods or services to customers, in an amount that reflects the expected consideration received in exchange for those goods or services. The guidance becomes effective for the Company beginning in the first quarter of fiscal 2019. Early adoption is not permitted. The new revenue standard may be applied retrospectively to each prior period presented or retrospectively with the cumulative effect recognized as of the date of adoption. The Company has not yet selected a transition method nor has the Company determined the impact of adopting the new revenue standard on its consolidated financial statements.

Fair Value Measurements (Tables

Fair Value Measurements (Tables)	9 Months Ended
	Jun. 30, 2015
Fair Value Disclosures [Abstract]
Available-for-sale securities	Available-for-sale marketable securities consisted of the following: June 30, 2015 Amortized Cost Gross Unrealized Holding Gains Gross Unrealized Holding Losses Fair Value (In thousands) Available-for-sale Level 1: Money market instruments $ 9,327 $ — $ — $ 9,327 Certificates of deposit 13,840 — — 13,840 Total 23,167 — — 23,167 Less: Amounts included in cash and cash equivalents (21,720 ) — — (21,720 ) $ 1,447 $ — $ — $ 1,447 September 30, 2014 Amortized Cost Gross Unrealized Holding Gains Gross Unrealized Holding Losses Fair Value (In thousands) Available-for-sale Level 1: Money market instruments $ 22,519 $ — $ — $ 22,519 Certificates of deposit 20,679 — — 20,679 Total 43,198 — — 43,198 Less: Amounts included in cash, cash equivalents and restricted cash (41,721 ) — — (41,721 ) $ 1,477 $ — $ — $ 1,477

Stock-based Compensation (Table

Stock-based Compensation (Tables)	9 Months Ended
	Jun. 30, 2015
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Schedule of total stock-based compensation	The following table outlines the effects of total stock-based compensation including expense related to SARs. Three Months Ended Nine Months Ended 2015 2014 2015 2014 (In thousands) Stock-based compensation Cost of sales $ 26 $ 50 $ 124 $ 154 Research and development 650 694 2,146 2,119 Selling, general and administrative 1,867 1,017 4,294 3,156 Total stock-based compensation 2,543 1,761 6,564 5,429 Tax effect on stock-based compensation (688 ) (330 ) (1,520 ) (1,018 ) Net effect on net income $ 1,855 $ 1,431 $ 5,044 $ 4,411 Compensation related to SARs included in total stock-based compensation $ 1,374 $ 222 $ 2,605 $ 844
Weighted average estimated fair values of option grants and rights and weighted average assumptions used in calculating values	The weighted average estimated fair values of stock option grants and rights granted under the ESPP, as well as the weighted average assumptions used in calculating these values during the three and nine month periods ended June 30, 2015 and 2014 were based on estimates at the date of grant as follows: Three Months Ended Nine Months Ended 2015 2014 2015 2014 Options Weighted-average fair value of grants $ — $ 6.13 $ 4.11 $ 4.70 Expected term in years — 4.42 4.27 4.42 Estimated volatility — % 51 % 38 % 51 % Risk-free interest rate — % 1.21 % 1.25 % 1.04 % Dividend yield — % — % 1.66 % — % ESPP Weighted-average fair value of grants $ — $ — $ — $ 2.66 Expected term in years — — — 0.49 Estimated volatility — % — % — % 27 % Risk-free interest rate — % — % — % 0.41 % Dividend yield — % — % — % — %
Summary of stock option activity and related information	A summary of the Company’s stock option activity and related information for the nine months ended June 30, 2015 follows (number of shares and aggregate intrinsic value are presented in thousands): Number of Shares Weighted-Average Exercise Price Weighted-Average Remaining Contractual Term in Years Aggregate Intrinsic Value Outstanding at September 30, 2014 4,240 $ 8.10 Granted 85 $ 14.83 Exercised (1,190 ) $ 7.67 $ 11,883 Cancelled/Expired (47 ) $ 10.84 Outstanding at June 30, 2015 3,088 $ 8.40 3.40 $ 42,421 Exercisable at June 30, 2015 2,192 $ 7.50 2.85 $ 32,077 Vested and expected to vest after June 30, 2015 3,057 $ 8.38 3.39 $ 42,082
Schedule of RSU activity and related information	A summary of the Company’s RSU activity and related information for the nine months ended June 30, 2015 under the 2007 Plan follows (number of shares and aggregate intrinsic value are presented in thousands): Number of Shares Weighted-Average Grant Date Fair Value Aggregate Intrinsic Value Outstanding at September 30, 2014 262 $ 9.91 Granted 230 $ 13.59 Vested (110 ) $ 9.43 $ 1,546 Forfeited (3 ) $ 13.22 Outstanding at June 30, 2015 379 $ 12.26 $ 8,385
Summary of SAR activity and related information	A summary of the Company’s SAR activity and related information for the nine months ended June 30, 2015 under the 2007 Plan follows (number of shares and aggregate intrinsic value are presented in thousands): Number of Shares Weighted-Average Exercise Price Weighted-Average Remaining Contractual Term in Years Aggregate Intrinsic Value Outstanding at September 30, 2014 747 $ 10.96 Granted 682 $ 13.55 Exercised (107 ) $ 13.55 $ 895 Cancelled/Expired (27 ) $ 12.17 Outstanding at June 30, 2015 1,295 $ 12.25 5.85 $ 12,811 Exercisable at June 30, 2015 247 $ 11.36 5.51 $ 2,662

Inventories (Tables)

Inventories (Tables)	9 Months Ended
	Jun. 30, 2015
Inventory Disclosure [Abstract]
Schedule of inventories by major category	The following is a summary of inventories by major category: June 30, September 30, (In thousands) Purchased components $ 25,001 $ 21,677 Work-in-process 22,959 27,058 Finished goods 39,481 36,358 $ 87,441 $ 85,093

Other Current Assets and Othe28

Other Current Assets and Other Assets (Tables)	9 Months Ended
	Jun. 30, 2015
Other Assets [Abstract]
Schedule of other current assets	Other current assets consisted of the following: June 30, September 30, (In thousands) Prepayments for Powerchip lease related assets $ 11,173 $ — Other current assets 17,106 17,033 $ 28,279 $ 17,033
Schedule of other assets	Other assets consisted of the following: June 30, September 30, (In thousands) Restricted assets $ 651 $ 499 Other investment 1,358 1,436 Nanya private placement shares 10,428 10,645 Technology licenses, net 15,339 10,644 Powerchip lease related assets 24,904 — Other 1,165 1,145 $ 53,845 $ 24,369

Purchased Intangible Assets (Ta

Purchased Intangible Assets (Tables)	9 Months Ended
	Jun. 30, 2015
Goodwill and Intangible Assets Disclosure [Abstract]
Schedule of total purchased intangible assets	The following tables present details of the Company’s total purchased intangible assets: Gross Accumulated Amortization Net (In thousands) June 30, 2015 Developed technology $ 5,330 $ 3,096 $ 2,234 Customer relationships 3,340 1,554 1,786 Other 450 419 31 Total $ 9,120 $ 5,069 $ 4,051 September 30, 2014 Developed technology $ 5,330 $ 2,584 $ 2,746 Customer relationships 3,340 1,137 2,203 Other 450 306 144 Total $ 9,120 $ 4,027 $ 5,093
Schedule of amortization expense of purchased intangible assets as reported in the consolidated statements of income	The following table presents details of the amortization expense of purchased intangible assets as reported in the consolidated statements of income: Three Months Ended Nine Months Ended 2015 2014 2015 2014 (In thousands) Reported as: Cost of sales $ 171 $ 191 $ 512 $ 656 Operating expenses 177 177 530 530 Total $ 348 $ 368 $ 1,042 $ 1,186
Schedule of estimated future amortization expense of purchased intangible assets	The following table presents the estimated future amortization expense of the Company’s purchased intangible assets at June 30, 2015 (in thousands). The weighted-average remaining amortization period for developed technology, customer relationships and other intangibles is 3.29 years, 3.21 years and 0.21 years, respectively. If the Company acquires additional purchased intangible assets in the future, its future amortization may be increased by those assets. Fiscal year Remainder of 2015 $ 341 2016 1,238 2017 1,238 2018 1,195 2019 39 Thereafter — Total $ 4,051

Borrowings (Tables)

Borrowings (Tables)	9 Months Ended
	Jun. 30, 2015
Debt Disclosure [Abstract]
Schedule of principal payments due	Principal payments due under the Loan are as follows (in thousands): Fiscal year Remainder of 2015 $ 49 2016 195 2017 195 2018 3,949 2019 — Thereafter — Total $ 4,388

Accumulated Other Comprehensi31

Accumulated Other Comprehensive Loss (Tables)	9 Months Ended
	Jun. 30, 2015
Stockholders' Equity Note [Abstract]
Components of accumulated other comprehensive loss, net of tax	The components of accumulated other comprehensive loss, net of tax, were as follows (in thousands): June 30, September 30, Accumulated foreign currency translation adjustments $ (2,120 ) $ 1,051 Accumulated net retirement plan transition asset (liability) (net of tax of $124 and $124, respectively) (36 ) 8 Accumulated net retirement plan actuarial losses (net of tax of $477 and $477, respectively) (2,016 ) (2,103 ) Total accumulated other comprehensive loss $ (4,172 ) $ (1,044 )
Significant amounts reclassified out of accumulated other comprehensive loss	The significant amounts reclassified out of accumulated other comprehensive loss into the consolidated condensed statements of income, with presentation location, during the three and nine months ended June 30, 2015 and June 30, 2014 were as follows: Three Months Ended Nine Months Ended 2015 2014 2015 2014 (In thousands) Comprehensive Income Components Amount Reclassified from Accumulated Other Comprehensive Loss Location Unrealized holding gains on available-for -sale investments $ — $ 1,616 $ — $ 9,618 Gain on the sale of investments — (592 ) — (3,589 ) Provision for income taxes $ — $ 1,024 $ — $ 6,029

Per Share Data (Tables)

Per Share Data (Tables)	9 Months Ended
	Jun. 30, 2015
Earnings Per Share [Abstract]
Computation of basic and diluted net income per share	The following table sets forth the computation of basic and diluted net income per share (in thousands, except per share amounts): Three Months Ended Nine Months Ended 2015 2014 2015 2014 Numerator for basic and diluted net income per share: Net income attributable to ISSI $ 16 $ 6,186 $ 4,318 $ 20,433 Denominator for basic net income per share: Weighted average common shares outstanding 31,950 30,312 31,495 29,816 Dilutive stock options and awards 1,902 1,651 1,805 1,521 Denominator for diluted net income per share 33,852 31,963 33,300 31,337 Basic net income per share $ — $ 0.20 $ 0.14 $ 0.69 Diluted net income per share $ — $ 0.19 $ 0.13 $ 0.65

Geographic and Segment Inform33

Geographic and Segment Information (Tables)	9 Months Ended
	Jun. 30, 2015
Segment Reporting [Abstract]
Summary of operations in different geographic areas	The following table summarizes the Company’s operations in different geographic areas: Three Months Ended Nine Months Ended 2015 2014 2015 2014 (In thousands) Net sales United States $ 10,148 $ 9,571 $ 30,254 $ 28,449 China 8,392 9,838 27,149 32,689 Hong Kong 15,049 16,456 43,444 45,499 Japan 7,753 5,916 20,371 16,569 Korea 3,289 4,000 11,112 10,544 Taiwan 10,416 12,344 32,186 35,099 Other Asia Pacific countries 5,332 6,435 16,858 18,390 Europe 20,608 19,587 60,138 56,207 Other 253 687 742 1,379 Total net sales $ 81,240 $ 84,834 $ 242,254 $ 244,825
Schedule of long lived assets in different geographic areas	June 30, September 30, (In thousands) Long-lived assets United States $ 11,171 $ 11,174 Hong Kong 10 14 China 13,956 12,908 Taiwan 32,909 34,751 $ 58,046 $ 58,847

Basis of Presentation (Details)

Basis of Presentation (Details) - USD ($) $ / shares in Units, $ in Thousands	1 Months Ended	9 Months Ended		12 Months Ended
	May. 31, 2013	Jun. 30, 2015	Jun. 30, 2014	Sep. 30, 2014	Sep. 30, 2015	Mar. 12, 2015	Sep. 14, 2012
Business Acquisition [Line Items]
Original offer price per share of outstanding shares						$ 19.25
Additional interest acquired		$ 0	$ 199
Chingis Technology Corporation
Business Acquisition [Line Items]
Percentage of interests acquired							94.10%
Percentage of additional voting interests acquired	4.80%			1.10%
Additional interest acquired	$ 1,600			$ 400
Percentage ownership of Chingis		100.00%
Scenario, Forecast
Business Acquisition [Line Items]
Acquisition price per share of outstanding shares					$ 23

Fair Value Measurements (Market

Fair Value Measurements (Marketable Equity and Cash Equivalents (Classified as Available-for-sale) and Cost Method Investments) (Details) - Fair Value, Inputs, Level 1 - USD ($) $ in Thousands	Jun. 30, 2015	Sep. 30, 2014
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	$ 23,167	$ 43,198
Gross Unrealized Holding Gains	0	0
Gross Unrealized Holding Losses	0	0
Fair Value	23,167	43,198
Money market instruments
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	9,327	22,519
Gross Unrealized Holding Gains	0	0
Gross Unrealized Holding Losses	0	0
Fair Value	9,327	22,519
Certificates of deposit
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	13,840	20,679
Gross Unrealized Holding Gains	0	0
Gross Unrealized Holding Losses	0	0
Fair Value	13,840	20,679
Cash and Cash Equivalents
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	21,720
Gross Unrealized Holding Gains	0
Gross Unrealized Holding Losses	0
Fair Value	21,720
Cash and Cash Equivalents and Restricted Cash
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost		41,721
Gross Unrealized Holding Gains		0
Gross Unrealized Holding Losses		0
Fair Value		41,721
Short-term Investments
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	1,447	1,477
Gross Unrealized Holding Gains	0	0
Gross Unrealized Holding Losses	0	0
Fair Value	$ 1,447	$ 1,477

Fair Value Measurements (Narrat

Fair Value Measurements (Narrative) (Details) - USD ($) $ in Millions	Jun. 30, 2015	Sep. 30, 2014
Foreign
Segment Reporting Information [Line Items]
Cash and cash equivalents, and short-term investments	$ 55.4	$ 71.9
China
Segment Reporting Information [Line Items]
Cash and cash equivalents, and short-term investments	$ 1.6

Stock-based Compensation (Narra

Stock-based Compensation (Narrative) (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended		9 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares available for future grant under the 2007 Plan	1,530,000		1,530,000
Vesting period			4 years
1995 Employee Stock Purchase Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Percentage discount from fair market value for shares purchased under the Employee Stock Purchase Plan			85.00%
Offering period			6 months
Shares available for future issuance under the Employee Stock Purchase Plan	0		0
Prior to October 1 2005
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Option expiration period			10 years
After October 1 2005
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Option expiration period			7 years
Minimum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Option Cliff vesting period			6 months
Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Option Cliff vesting period			1 year
Restricted Stock Units (RSUs)
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Weighted-average fair value of grants	$ 18.70	$ 14.45	$ 13.59	$ 11.62
Restricted Stock Units (RSUs) | Minimum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period			2 years
Restricted Stock Units (RSUs) | Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period			4 years
SARS
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period			4 years
Option expiration period			7 years
Total unrecognized stock-based compensation expense	$ 10.5		$ 10.5
Nonvested awards, total compensation cost not yet recognized, period for recognition			2 years 10 months 10 days
SARS | Minimum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Option Cliff vesting period			6 months
SARS | Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Option Cliff vesting period			1 year
Options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total unrecognized stock-based compensation expense	$ 7.7		$ 7.7
Nonvested awards, total compensation cost not yet recognized, period for recognition			2 years 2 months 5 days

Stock-based Compensation (Sched

Stock-based Compensation (Schedule of Employee Service Share-based Compensation, Allocation of Recognized Period Costs) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Allocated share-based compensation expense	$ 2,543	$ 1,761	$ 6,564	$ 5,429
Tax effect on stock-based compensation	(688)	(330)	(1,520)	(1,018)
Net effect on net income	1,855	1,431	5,044	4,411
SARS
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Net effect on net income	1,374	222	2,605	844
Cost of sales
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Allocated share-based compensation expense	26	50	124	154
Research and development
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Allocated share-based compensation expense	650	694	2,146	2,119
Selling, general and administrative
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Allocated share-based compensation expense	$ 1,867	$ 1,017	$ 4,294	$ 3,156

Stock-based Compensation (Share

Stock-based Compensation (Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Weighted Average Grant Date Fair Value) (Details) - $ / shares	3 Months Ended		9 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Weighted-average fair value of grants	$ 0	$ 6.13	$ 4.11	$ 4.70
Expected term in years		4 years 5 months 1 day	4 years 3 months 7 days	4 years 5 months 1 day
Estimated volatility	0.00%	51.00%	38.00%	51.00%
Risk-free interest rate	0.00%	1.21%	1.25%	1.04%
Dividend yield	0.00%	0.00%	1.66%	0.00%
ESPP
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Weighted-average fair value of grants	$ 0	$ 0	$ 0	$ 2.66
Expected term in years				5 months 27 days
Estimated volatility	0.00%	0.00%	0.00%	27.00%
Risk-free interest rate	0.00%	0.00%	0.00%	0.41%
Dividend yield	0.00%	0.00%	0.00%	0.00%

Stock-based Compensation (Sha40

Stock-based Compensation (Share-based Compensation Arrangement by Share-based Payment Award, Options, Vested and Expected to Vest, Outstanding and Exercisable) (Details) - Jun. 30, 2015 - Options - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	Total
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding [Roll Forward]
Outstanding at September 30, 2014	4,240
Granted	85
Exercised	(1,190)
Cancelled/Expired	(47)
Outstanding at June 30, 2015	3,088
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Exercise Price [Roll Forward]
Outstanding at September 30, 2014	$ 8.10
Granted	14.83
Exercised	7.67
Cancelled/Expired	10.84
Outstanding at June 30, 2015	$ 8.40
Aggregate Intrinsic Value, options exercised	$ 11,883
Weighted-Average Remaining Contractual Term in Years, Outstanding at June 30, 2015	3 years 4 months 24 days
Aggregate Intrinsic Value, Outstanding at June 30, 2015	$ 42,421
Number of Shares, Exercisable at June 30, 2015 (shares)	2,192
Weighted-Average Exercise Price, Exercisable at June 30, 2015	$ 7.50
Weighted-Average Remaining Contractual Term in Years, Exercisable at June 30, 2015	2 years 10 months 6 days
Aggregate Intrinsic Value, Exercisable at June 30, 2015	$ 32,077
Number of Shares, Vested and expected to vest after June 30, 2015 (shares)	3,057
Weighted-Average Exercise Price, Vested and expected to vest after June 30, 2015	$ 8.38
Weighted-Average Remaining Contractual Term in Years, Vested and expected to vest after June 30, 2015	3 years 4 months 21 days
Aggregate Intrinsic Value, Vested and expected to vest after June 30, 2015	$ 42,082

Stock-based Compensation (Restr

Stock-based Compensation (Restricted Stock and Restricted Stock Units Activity) (Details) - Restricted Stock Units (RSUs) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number of Shares [Roll Forward]
Outstanding at September 30, 2014			262
Granted			230
Vested			(110)
Forfeited			(3)
Outstanding at June 30, 2015	379		379
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value [Roll Forward]
Outstanding at September 30, 2014, Weighted-Average Grant Date Fair Value			$ 9.91
Weighted-average fair value of grants	$ 18.70	$ 14.45	13.59	$ 11.62
Weighted average grant date fair value, vested			9.43
Weighted average grant date fair value, forfeited			13.22
Outstanding at June 30, 2015, Weighted-Average Grant Date Fair Value	$ 12.26		$ 12.26
Aggregate Intrinsic Value, Vested			$ 1,546
Aggregate Intrinsic Value, Outstanding at June 30, 2015	$ 8,385		$ 8,385

Stock-based Compensation (Sch42

Stock-based Compensation (Schedule of SAR Activity) (Details) - Jun. 30, 2015 - SARS - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	Total
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number of Shares [Roll Forward]
Outstanding at September 30, 2014	747
Granted	682
Exercised	(107)
Cancelled/Expired	(27)
Outstanding at June 30, 2015	1,295
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Exercise Price [Roll Forward]
Outstanding at September 30, 2014	$ 10.96
Granted	13.55
Exercised	13.55
Cancelled/Expired	12.17
Outstanding at June 30, 2015	$ 12.25
Aggregate Intrinsic Value, exercised	$ 895
Weighted-Average Remaining Contractual Term in Years, Outstanding at June 30, 2015	5 years 10 months 6 days
Aggregate Intrinsic Value, Outstanding at June 30, 2015	$ 12,811
Number of Shares, Exercisable at June 30, 2015 (shares)	247
Weighted-Average Exercise Price, Exercisable at June 30, 2015	$ 11.36
Weighted-Average Remaining Contractual Term in Years, Exercisable at June 30, 2015	5 years 6 months 4 days
Aggregate Intrinsic Value, Exercisable at June 30, 2015	$ 2,662

Concentrations (Narrative) (Det

Concentrations (Narrative) (Details) - Sales Revenue, Goods, Net	3 Months Ended		9 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Largest Distributor
Concentration Risk [Line Items]
Concentration risk, largest customers	18.00%	20.00%	16.00%	18.00%
Second Largest Distributor
Concentration Risk [Line Items]
Concentration risk, largest customers	11.00%	12.00%	13.00%	13.00%

Inventories (Schedule of Invent

Inventories (Schedule of Inventory, Current by major category) (Details) - USD ($) $ in Thousands	Jun. 30, 2015	Sep. 30, 2014
Inventory Disclosure [Abstract]
Purchased components	$ 25,001	$ 21,677
Work-in-process	22,959	27,058
Finished goods	39,481	36,358
Inventories	$ 87,441	$ 85,093	[1]
[1]	Derived from audited financial statements.

Inventories (Narrative) (Detail

Inventories (Narrative) (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Inventory Disclosure [Abstract]
Inventory write-downs	$ 1.5	$ 2.1	$ 4.7	$ 4.3

Other Current Assets and Othe46

Other Current Assets and Other Assets (Schedule of Other Current Assets) (Details) - USD ($) $ in Thousands	Jun. 30, 2015	Sep. 30, 2014
Capital Leased Assets [Line Items]
Other current assets	$ 17,106	$ 17,033
Total other current assets	28,279	17,033	[1]
Powerchip Technology Corporation | Equipment Leased to Other Party
Capital Leased Assets [Line Items]
Prepayments for Powerchip lease related assets	$ 11,173	$ 0
[1]	Derived from audited financial statements.

Other Current Assets and Othe47

Other Current Assets and Other Assets (Schedule of Other Assets) (Details) - USD ($) $ in Thousands	Jun. 30, 2015	Sep. 30, 2014		Mar. 31, 2012
Finite-Lived Intangible Assets [Line Items]
Restricted assets	$ 651	$ 499
Other investment	1,358	1,436		$ 2,000
Nanya private placement shares	10,428	10,645
Other	1,165	1,145
Other assets	53,845	24,369	[1]
Technology licenses, net
Finite-Lived Intangible Assets [Line Items]
Technology licenses, net	15,339	10,644
Powerchip Technology Corporation | Equipment Leased to Other Party
Finite-Lived Intangible Assets [Line Items]
Powerchip lease related assets	$ 24,904	$ 0
[1]	Derived from audited financial statements.

Other Current Assets and Othe48

Other Current Assets and Other Assets (Narrative) (Details) - USD ($) $ in Thousands	Apr. 20, 2015	Jun. 30, 2015	Jun. 30, 2014	Sep. 30, 2014	Mar. 31, 2012
Entity Information [Line Items]
Termination period		1 year
Amount the company will purchase and then lease (up to aggregate of $73.5 million)		$ 20,574	$ 0
Other investment		$ 1,358		$ 1,436	$ 2,000
Hong Kong
Entity Information [Line Items]
Equity method investment ownership percentage		25.00%
Equipment Leased to Other Party | Powerchip Technology Corporation
Entity Information [Line Items]
Amount the company will purchase and then lease (up to aggregate of $73.5 million)	$ 73,500
Powerchip lease related assets		$ 24,904		$ 0
Term of lease agreements	6 years
Amount of quarterly payments	$ 82,100
Additional renewal period	3 years
Technology licenses, net | Minimum
Entity Information [Line Items]
Estimated useful lives		3 years
Technology licenses, net | Maximum
Entity Information [Line Items]
Estimated useful lives		15 years

Purchased Intangible Assets (Sc

Purchased Intangible Assets (Schedule of Finite-Lived Intangible Assets by Major Class) (Details) - USD ($) $ in Thousands	Jun. 30, 2015	Sep. 30, 2014
Finite-Lived Intangible Assets [Line Items]
Gross	$ 9,120	$ 9,120
Accumulated Amortization	5,069	4,027
Net	4,051
Total, Net	4,051	5,093	[1]
Developed technology
Finite-Lived Intangible Assets [Line Items]
Gross	5,330	5,330
Accumulated Amortization	3,096	2,584
Net	2,234	2,746
Customer relationships
Finite-Lived Intangible Assets [Line Items]
Gross	3,340	3,340
Accumulated Amortization	1,554	1,137
Net	1,786	2,203
Other
Finite-Lived Intangible Assets [Line Items]
Gross	450	450
Accumulated Amortization	419	306
Net	$ 31	$ 144
[1]	Derived from audited financial statements.

Purchased Intangible Assets (50

Purchased Intangible Assets (Schedule of Current Finite-Lived Intangible Asset Amortization Expense by Income Statement Line Item) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Schedule of Current Intangible Asset Amortization Expense By Income Statement Line Item [Line Items]
Amortization of intangibles	$ 348	$ 368	$ 1,042	$ 1,186
Cost of sales
Schedule of Current Intangible Asset Amortization Expense By Income Statement Line Item [Line Items]
Amortization of intangibles	171	191	512	656
Operating expenses
Schedule of Current Intangible Asset Amortization Expense By Income Statement Line Item [Line Items]
Amortization of intangibles	$ 177	$ 177	$ 530	$ 530

Purchased Intangible Assets (Na

Purchased Intangible Assets (Narrative) (Details)	9 Months Ended
	Jun. 30, 2015
Developed technology
Acquired Indefinite-lived Intangible Assets [Line Items]
Weighted average useful life for intangibles (years)	3 years 3 months 15 days
Customer relationships
Acquired Indefinite-lived Intangible Assets [Line Items]
Weighted average useful life for intangibles (years)	3 years 2 months 16 days
Other
Acquired Indefinite-lived Intangible Assets [Line Items]
Weighted average useful life for intangibles (years)	2 months 15 days

Purchased Intangible Assets (52

Purchased Intangible Assets (Schedule Finite-Lived Intangible Assets, Future Amortization Expense) (Details) $ in Thousands	Jun. 30, 2015USD ($)
Goodwill and Intangible Assets Disclosure [Abstract]
Remainder of 2015	$ 341
2,016	1,238
2,017	1,238
2,018	1,195
2,019	39
Thereafter	0
Net	$ 4,051

Borrowings (Narrative) (Details

Borrowings (Narrative) (Details) - Secured Debt $ in Millions	1 Months Ended
	Dec. 31, 2012USD ($)aft²	Jun. 30, 2015
Debt Instrument [Line Items]
Amount of bank loan	$ 4.9
Purchase price of headquarters	$ 6.5
Acres of land | a	2.85
Square footage of building | ft²	55,612
LIBOR
Debt Instrument [Line Items]
Interest rate spread above LIBOR	1.00%
LIBOR	LIBOR
Interest rate on loan at period end		1.25%

Borrowings (Schedule of Maturit

Borrowings (Schedule of Maturities of Debt) (Details) - Secured Debt $ in Thousands	Jun. 30, 2015USD ($)
Debt Instrument [Line Items]
Remainder of 2015	$ 49
2,016	195
2,017	195
2,018	3,949
2,019	0
Thereafter	0
Total	$ 4,388

Accumulated Other Comprehensi55

Accumulated Other Comprehensive Loss (Schedule of Accumulated Other Comprehensive Income (Loss)) (Details) - USD ($) $ in Thousands	Jun. 30, 2015	Sep. 30, 2014
Stockholders' Equity Note [Abstract]
Accumulated foreign currency translation adjustments	$ (2,120)	$ 1,051
Accumulated net retirement plan transition asset (liability) (net of tax of $124 and $124, respectively)	(36)	8
Accumulated net retirement plan actuarial losses (net of tax of $477 and $477, respectively)	(2,016)	(2,103)
Total accumulated other comprehensive loss	(4,172)	(1,044)	[1]
Accumulated net retirement plan transition asset, tax	124	124
Accumulated net retirement plan actuarial losses, tax	$ 477	$ 477
[1]	Derived from audited financial statements.

Accumulated Other Comprehensi56

Accumulated Other Comprehensive Loss (Schedule of Reclassification out of Accumulated Other Comprehensive Income) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Gain on sale of investments	$ 0	$ 2,140	$ 0	$ 11,300
Provision for income taxes	461	(2,388)	(1,147)	(6,941)
Consolidated net income	22	6,227	4,389	20,631
Amount Reclassified from Accumulated Other Comprehensive Loss | Unrealized holding gains on available-for-sale investments
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Gain on sale of investments	0	1,616	0	9,618
Provision for income taxes	0	(592)	0	(3,589)
Consolidated net income	$ 0	$ 1,024	$ 0	$ 6,029

Income Taxes (Narrative) (Detai

Income Taxes (Narrative) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Income Tax Disclosure [Abstract]
Income tax expense	$ (461)	$ 2,388	$ 1,147	$ 6,941
Effective tax rate	104.00%	28.00%	21.00%	25.00%
Federal statutory rate	35.00%	35.00%	35.00%	35.00%

Per Share Data (Calculation of

Per Share Data (Calculation of Basic and Diluted EPS) (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Earnings Per Share [Abstract]
Net income attributable to ISSI	$ 16	$ 6,186	$ 4,318	$ 20,433
Denominator for basic net income per share:
Weighted average common shares outstanding	31,950	30,312	31,495	29,816
Dilutive stock options and awards (in shares)	1,902	1,651	1,805	1,521
Denominator for diluted net income per share (in shares)	33,852	31,963	33,300	31,337
Basic net income per share (in dollars per share)	$ 0	$ 0.20	$ 0.14	$ 0.69
Diluted net income per share (in dollars per share)	$ 0	$ 0.19	$ 0.13	$ 0.65

Per Share Data (Narrative) (Det

Per Share Data (Narrative) (Details) - shares shares in Thousands	3 Months Ended		9 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Earnings Per Share [Abstract]
Stock options and awards excluded from diluted earnings per share (shares)	46	686	100	1,070

Common Stock Repurchase Progr60

Common Stock Repurchase Program (Narrative) (Details) - Jun. 30, 2015 - USD ($) $ in Millions	Total	Total
Common Stock Repurchase Program [Abstract]
Stock repurchased and retired during period (shares)		14,179,711
Stock repurchased and retired during period, value		$ 88.5
Stock repurchase program, remaining authorized repurchase amount	$ 19.8	$ 19.8
Shares paid for tax withholding for share based compensation (shares)	36,891
Payments related to tax withholding for share-based compensation	$ 0.5

Commitments and Contingencies (

Commitments and Contingencies (Narrative) (Details) $ in Millions	Jun. 30, 2015USD ($)	Apr. 01, 2015complaint
Loss Contingencies [Line Items]
Amount of purchase orders that had been entered into wafer work-in-process	$ 20.9
Stockholder Class Action Complaints | Pending Litigation
Loss Contingencies [Line Items]
Number of stockholder class action complaints | complaint		3

Geographic and Segment Inform62

Geographic and Segment Information (Narrative) (Details)	9 Months Ended
	Jun. 30, 2015Business_Segment
Segment Reporting [Abstract]
Number of operating segments	1

Geographic and Segment Inform63

Geographic and Segment Information (Schedule of Revenues, by Geographical Areas) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Revenues from External Customers and Long-Lived Assets [Line Items]
Net sales	$ 81,240	$ 84,834	$ 242,254	$ 244,825
United States
Revenues from External Customers and Long-Lived Assets [Line Items]
Net sales	10,148	9,571	30,254	28,449
China
Revenues from External Customers and Long-Lived Assets [Line Items]
Net sales	8,392	9,838	27,149	32,689
Hong Kong
Revenues from External Customers and Long-Lived Assets [Line Items]
Net sales	15,049	16,456	43,444	45,499
Japan
Revenues from External Customers and Long-Lived Assets [Line Items]
Net sales	7,753	5,916	20,371	16,569
Korea
Revenues from External Customers and Long-Lived Assets [Line Items]
Net sales	3,289	4,000	11,112	10,544
Taiwan
Revenues from External Customers and Long-Lived Assets [Line Items]
Net sales	10,416	12,344	32,186	35,099
Other Asia Pacific countries
Revenues from External Customers and Long-Lived Assets [Line Items]
Net sales	5,332	6,435	16,858	18,390
Europe
Revenues from External Customers and Long-Lived Assets [Line Items]
Net sales	20,608	19,587	60,138	56,207
Other
Revenues from External Customers and Long-Lived Assets [Line Items]
Net sales	$ 253	$ 687	$ 742	$ 1,379

Geographic and Segment Inform64

Geographic and Segment Information (Schedule of Long-Lived Assets, by Geographical Areas) (Details) - USD ($) $ in Thousands	Jun. 30, 2015	Sep. 30, 2014
Revenues from External Customers and Long-Lived Assets [Line Items]
Long-lived assets	$ 58,046	$ 58,847
United States
Revenues from External Customers and Long-Lived Assets [Line Items]
Long-lived assets	11,171	11,174
Hong Kong
Revenues from External Customers and Long-Lived Assets [Line Items]
Long-lived assets	10	14
China
Revenues from External Customers and Long-Lived Assets [Line Items]
Long-lived assets	13,956	12,908
Taiwan
Revenues from External Customers and Long-Lived Assets [Line Items]
Long-lived assets	$ 32,909	$ 34,751

Related Party Transactions (Nar

Related Party Transactions (Narrative) (Details) - Jimmy S.M. Lee, Executive Chairman - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014	Sep. 30, 2014
Related Party Transaction [Line Items]
Revenue from related parties	$ 0	$ 80	$ 144	$ 162
Accounts receivable, related parties	$ 0		$ 0		$ 59