CMC Materials (CCMP) 10-K 20 Nov 13 2013 FY Annual report Financial data

Document_and_Entity_Informatio

Document and Entity Information (USD $)	12 Months Ended
	Sep. 30, 2013	Oct. 31, 2013	Mar. 31, 2013
Document and Entity Information [Abstract]	'	'	'
Entity Registrant Name	'CABOT MICROELECTRONICS CORP	'	'
Entity Central Index Key	'0001102934	'	'
Current Fiscal Year End Date	'--09-30	'	'
Entity Well-known Seasoned Issuer	'Yes	'	'
Entity Voluntary Filers	'No	'	'
Entity Current Reporting Status	'Yes	'	'
Entity Filer Category	'Large Accelerated Filer	'	'
Entity Public Float	'	'	$787,314,700
Entity Common Stock, Shares Outstanding	'	23,584,873	'
Document Fiscal Year Focus	'2013	'	'
Document Fiscal Period Focus	'FY	'	'
Document Type	'10-K	'	'
Amendment Flag	'false	'	'
Document Period End Date	30-Sep-13	'	'

CONSOLIDATED_STATEMENTS_OF_INC

CONSOLIDATED STATEMENTS OF INCOME (USD $)	3 Months Ended								12 Months Ended
In Thousands, except Share data, unless otherwise specified	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2011	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2011
CONSOLIDATED STATEMENTS OF INCOME [Abstract]	'	'	'	'	'	'	'	'	'	'	'
Revenue	$116,266	$109,968	$100,364	$106,533	$110,621	$115,678	$99,236	$102,122	$433,131	$427,657	$445,442
Cost of goods sold	57,143	55,359	52,019	56,494	56,883	60,462	53,442	52,843	221,015	223,630	231,336
Gross profit	59,123	54,609	48,345	50,039	53,738	55,216	45,794	49,279	212,116	204,027	214,106
Operating expenses:	'	'	'	'	'	'	'	'	'	'	'
Research, development and technical	15,835	15,149	15,073	15,316	15,401	15,415	14,071	13,755	61,373	58,642	58,035
Selling and marketing	7,360	6,470	7,046	7,109	7,288	7,458	7,434	7,336	27,985	29,516	29,758
General and administrative	12,270	10,776	12,287	10,954	10,572	10,695	15,177	12,901	46,287	49,345	45,928
Total operating expenses	35,465	32,395	34,406	33,379	33,261	33,568	36,682	33,992	135,645	137,503	133,721
Operating income (loss)	23,658	22,214	13,939	16,660	20,477	21,648	9,112	15,287	76,471	66,524	80,385
Interest expense	911	907	872	953	961	955	354	39	3,643	2,309	155
Other income (expense), net	-173	248	463	854	-681	-864	97	104	1,392	-1,344	-1,318
Income (loss) before income taxes	22,574	21,555	13,530	16,561	18,835	19,829	8,855	15,352	74,220	62,871	78,912
Provision for income taxes	5,805	6,062	4,110	6,858	7,196	6,587	3,325	4,937	22,835	22,045	27,250
Net income (loss)	$16,769	$15,493	$9,420	$9,703	$11,639	$13,242	$5,530	$10,415	$51,385	$40,826	$51,662
Basic earnings per share (in dollars per share)	$0.72	$0.68	$0.41	$0.42	$0.51	$0.57	$0.24	$0.46	$2.22	$1.81	$2.26
Weighted average basic shares outstanding (in shares)	23,041,000	22,951,000	22,974,000	22,845,000	22,920,000	23,120,000	22,768,000	22,508,000	22,924,056	22,506,408	22,895,568
Diluted earnings per share (in dollars per share)	$0.69	$0.65	$0.40	$0.41	$0.49	$0.55	$0.23	$0.45	$2.14	$1.75	$2.20
Weighted average diluted shares outstanding (in shares)	23,994,000	23,776,000	23,871,000	23,658,000	23,706,000	23,939,000	23,780,000	22,926,000	23,760,066	23,280,298	23,434,604
Dividends per share (in dollars per share)	$0	$0	$0	$0	$0	$0	$15	$0	$0	$15	$0

CONSOLIDATED_STATEMENTS_OF_COM

CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2011
CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME [Abstract]	'	'	'
Net income	$51,385	$40,826	$51,662
Other comprehensive income (loss), net of tax [Abstract]	'	'	'
Foreign currency translation adjustments	-13,037	6,876	5,490
Minimum pension liability adjustment	7	-537	99
Other comprehensive income (loss), net of tax	-13,030	6,339	5,589
Comprehensive income	$38,355	$47,165	$57,251

CONSOLIDATED_BALANCE_SHEETS

CONSOLIDATED BALANCE SHEETS (USD $)	Sep. 30, 2013	Sep. 30, 2012
In Thousands, unless otherwise specified
Current assets:	'	'
Cash and cash equivalents	$226,029	$178,459
Accounts receivable, less allowance for doubtful accounts of $1,532 at September 30, 2013, and $4,757 at September 30, 2012	54,640	53,506
Inventories	63,786	66,472
Prepaid expenses and other current assets	13,598	12,608
Deferred income taxes	7,659	6,843
Total current assets	365,712	317,888
Property, plant and equipment, net	111,985	125,020
Goodwill	44,306	44,620
Other intangible assets, net	9,785	12,473
Deferred income taxes	10,291	5,879
Other long-term assets	12,427	11,945
Total assets	554,506	517,825
Current liabilities:	'	'
Accounts payable	16,663	19,542
Current portion of long-term debt	10,938	10,937
Capital lease obligations	0	2
Accrued expenses, income taxes payable and other current liabilities	39,899	32,738
Total current liabilities	67,500	63,219
Long-term debt, net of current portion	150,937	161,875
Deferred income taxes	1,559	2,017
Capital lease obligations, net of current portion	0	19
Other long-term liabilities	7,433	7,104
Total liabilities	227,429	234,234
Commitments and contingencies (Note 16)	'	'
Stockholders' equity:	'	'
Common Stock: Authorized: 200,000,000 shares, $0.001 par value; Issued: 30,213,577 shares at September 30, 2013, and 28,864,527 shares at September 30, 2012	30	29
Capital in excess of par value of common stock	376,206	329,782
Retained earnings	180,826	129,441
Accumulated other comprehensive income	17,436	30,466
Treasury stock at cost, 6,866,675 shares at September 30, 2013, and 5,682,288 shares at September 30, 2012	-247,421	-206,127
Total stockholders' equity	327,077	283,591
Total liabilities and stockholders' equity	$554,506	$517,825

CONSOLIDATED_BALANCE_SHEETS_Pa

CONSOLIDATED BALANCE SHEETS (Parenthetical) (USD $)	Sep. 30, 2013	Sep. 30, 2012
In Thousands, except Share data, unless otherwise specified
Current assets:	'	'
Allowance for doubtful accounts	$1,532	$4,757
Stockholders' equity:	'	'
Common stock: Authorized (in shares)	200,000,000	200,000,000
Common stock: par value (in dollars per share)	$0.00	$0.00
Common stock: Issued (in shares)	30,213,577	28,864,527
Treasury stock at cost, shares (in shares)	6,866,675	5,682,288

CONSOLIDATED_STATEMENTS_OF_CAS

CONSOLIDATED STATEMENTS OF CASH FLOWS (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2011
Cash flows from operating activities:	'	'	'
Net income	$51,385	$40,826	$51,662
Adjustments to reconcile net income to net cash provided by operating activities:	'	'	'
Depreciation and amortization	20,457	23,545	23,992
Provision for doubtful accounts	173	3,771	-18
Share-based compensation expense	13,350	13,306	12,646
Deferred income tax expense (benefit)	-3,118	-3,523	4,934
Non-cash foreign exchange (gain)/ loss	3,832	748	-212
Loss on disposal of property, plant and equipment	551	247	140
Impairment of property, plant and equipment	160	968	198
Other	-2,175	-925	-723
Changes in operating assets and liabilities:	'	'	'
Accounts receivable	-5,936	-4,622	6,623
Inventories	-1,683	-10,228	-2,816
Prepaid expenses and other assets	-2,087	432	-658
Accounts payable	-1,359	2,026	-1,021
Accrued expenses, income taxes payable and other liabilities	11,933	-164	-1,181
Net cash provided by operating activities	85,483	66,407	93,566
Cash flows from investing activities:	'	'	'
Additions to property, plant and equipment	-14,633	-19,586	-28,052
Proceeds from the sale of property, plant and equipment	20	8	41
Purchase of intangible assets	0	-155	-200
Proceeds from the sale of investments	25	50	25
Net cash used in investing activities	-14,588	-19,683	-28,186
Cash flows from financing activities:	'	'	'
Dividends paid	0	-347,140	0
Issuance of long-term debt	0	175,000	0
Repayment of long-term debt	-10,937	-2,188	0
Repurchases of common stock	-41,294	-34,537	-55,499
Net proceeds from issuance of stock	30,905	36,497	38,051
Tax benefits associated with share-based compensation expense	1,148	636	830
Principal payments under capital lease obligations	-21	-11	-1,296
Net cash used in financing activities	-20,199	-171,743	-17,914
Effect of exchange rate changes on cash	-3,126	932	916
Increase (decrease) in cash	47,570	-124,087	48,382
Cash and cash equivalents at beginning of year	178,459	302,546	254,164
Cash and cash equivalents at end of year	226,029	178,459	302,546
Supplemental disclosure of cash flow information:	'	'	'
Cash paid for income taxes	17,661	22,701	19,788
Cash paid for interest	3,643	2,336	158
Supplemental disclosure of non-cash investing and financing activities:	'	'	'
Purchases of property, plant and equipment in accrued liabilities and accounts payable at the end of period	1,232	1,894	6,322
Issuance of restricted stock	5,926	6,374	6,774
Assets acquired under capital lease	$0	$20	$0

CONSOLIDATED_STATEMENT_OF_CHAN

CONSOLIDATED STATEMENT OF CHANGES IN STOCKHOLDER'S EQUITY (USD $)	Total	Common Stock [Member]	Capital In Excess Of Par [Member]	Retained Earnings [Member]	Accumulated Other Comprehensive Income [Member]	Treasury Stock [Member]
In Thousands
Balance at Sep. 30, 2010	$514,343	$26	$228,103	$383,767	$18,538	($116,091)
Share-based compensation expense	12,646	'	12,646	'	'	'
Repurchases of common stock under share repurchase plans, at cost	-54,106	'	'	'	'	-54,106
Repurchases of common stock - other, at cost	-1,393	'	'	'	'	-1,393
Exercise of stock options	35,955	2	35,953	'	'	'
Issuance of Cabot Microelectronics restricted stock under deposit share plan	145	'	145	'	'	'
Issuance of Cabot Microelectronics stock under Employee Stock Purchase Plan	1,951	'	1,951	'	'	'
Tax deduction for the exercise of stock options granted prior to adoption of ASC 718	262	'	262	'	'	'
Deferred tax effect of long-term incentives	-700	'	-700	'	'	'
Net income	51,662	'	'	51,662	'	'
Foreign currency translation adjustment	5,490	'	'	'	5,490	'
Minimum pension liability adjustment	99	'	'	'	99	'
Balance at Sep. 30, 2011	566,354	28	278,360	435,429	24,127	-171,590
Share based compensation expense, net of compensation related to dividends on unvested restricted stock	12,980	'	12,980	'	'	'
Repurchases of common stock under share repurchase plans, at cost	-33,026	'	'	'	'	-33,026
Repurchases of common stock - other, at cost	-1,511	'	'	'	'	-1,511
Exercise of stock options	34,107	1	34,106	'	'	'
Issuance of Cabot Microelectronics restricted stock under deposit share plan	155	'	155	'	'	'
Issuance of Cabot Microelectronics stock under Employee Stock Purchase Plan	2,228	'	2,228	'	'	'
Dividends paid, net of expected forfeitures of unvested restricted stock	-346,814	'	'	-346,814	'	'
Tax deduction for the exercise of stock options granted prior to adoption of ASC 718	498	'	498	'	'	'
Tax deduction for the dividend paid on unvested restricted stock, net of expected forfeitures	1,455	'	1,455	'	'	'
Net income	40,826	'	'	40,826	'	'
Foreign currency translation adjustment	6,876	'	'	'	6,876	'
Minimum pension liability adjustment	-537	'	'	'	-537	'
Balance at Sep. 30, 2012	283,591	29	329,782	129,441	30,466	-206,127
Share-based compensation expense	13,350	'	13,350	'	'	'
Repurchases of common stock under share repurchase plans, at cost	-40,000	'	'	'	'	-40,000
Repurchases of common stock - other, at cost	-1,294	'	'	'	'	-1,294
Exercise of stock options	28,526	1	28,525	'	'	'
Issuance of Cabot Microelectronics restricted stock under deposit share plan	154	'	154	'	'	'
Issuance of Cabot Microelectronics stock under Employee Stock Purchase Plan	2,226	'	2,226	'	'	'
Tax deduction for the exercise of stock options granted prior to adoption of ASC 718	2,169	'	2,169	'	'	'
Net income	51,385	'	'	51,385	'	'
Foreign currency translation adjustment	-13,037	'	'	'	-13,037	'
Minimum pension liability adjustment	7	'	'	'	7	'
Balance at Sep. 30, 2013	$327,077	$30	$376,206	$180,826	$17,436	($247,421)

BACKGROUND_AND_BASIS_OF_PRESEN

BACKGROUND AND BASIS OF PRESENTATION	12 Months Ended
	Sep. 30, 2013
BACKGROUND AND BASIS OF PRESENTATION [Abstract]	'
BACKGROUND AND BASIS OF PRESENTATION	'
	1. BACKGROUND AND BASIS OF PRESENTATION
	Cabot Microelectronics Corporation ("Cabot Microelectronics'', "the Company'', "us'', "we'' or "our'') supplies high-performance polishing slurries and pads used in the manufacture of advanced integrated circuit (IC) devices within the semiconductor industry, in a process called chemical mechanical planarization (CMP).  CMP polishes surfaces at an atomic level, thereby enabling IC device manufacturers to produce smaller, faster and more complex IC devices with fewer defects.    We develop, produce and sell CMP slurries for polishing many of the conducting and insulating materials used in IC devices, and also for polishing the disk substrates and magnetic heads used in hard disk drives.  We also develop, manufacture and sell CMP polishing pads, which are used in conjunction with slurries in the CMP process.  We also pursue other demanding surface modification applications through our Engineered Surface Finishes (ESF) business where we believe we can leverage our expertise in CMP consumables for the semiconductor industry to develop products for demanding polishing applications in other industries.
	The audited consolidated financial statements have been prepared by us pursuant to the rules of the Securities and Exchange Commission (SEC) and accounting principles generally accepted in the United States of America.  We operate predominantly in one industry segment - the development, manufacture, and sale of CMP consumables.  Reclassifications of prior period amounts have been made to separate interest expense from other income (expense) to conform to the current period presentation.
	Results of Operations
	The results of operations for the fiscal year ended September 30, 2013 include certain adjustments to correct prior period amounts, which we determined to be immaterial to the prior periods to which they relate.  These adjustments included the correction of a foreign deferred tax asset recorded in the first quarter of fiscal 2013 and the correction of additional historical tax accounting recorded in the fourth quarter of fiscal 2013.  The correction of the foreign tax asset related to the reversal of a $1,686 deferred tax asset for cumulative net operating losses (NOLs) associated with our facility in South Korea since its opening in fiscal year 2011, as these NOLs are expected to be consumed during periods a tax holiday is in effect.  Additional tax accounting related corrections resulted in a reduction of income tax expense of $381 and adjustments to the Consolidated Balance Sheet including: an increase of $775 in deferred tax assets; an increase of $775 in additional paid-in capital; a decrease of $299 in income taxes payable; and a decrease of $82 in deferred tax liabilities.  Collectively, these adjustments reduced net income for fiscal 2013 by $1,305 and diluted earnings per share by approximately $0.05.
	The results of operations for the fiscal year ended September 30, 2012 include certain adjustments to correct prior period amounts, which we have determined to be immaterial to the current period and the prior periods to which they relate.  These adjustments included the correction of historical tax accounting related to the acquisition of Epoch Material Co., Ltd. (Epoch) in fiscal 2009 and the correction of prior period remeasurement of certain foreign cash balances into their functional currency amounts, which were recorded in the third quarter of fiscal 2012, and the correction of additional historical tax accounting recorded in the fourth quarter of fiscal 2012.  The correction of tax accounting related to the Epoch acquisition resulted in additional income tax expense of $172 in the Consolidated Statement of Income and adjustments to the Consolidated Balance Sheet including: an increase of $2,172 in cumulative translation adjustment within accumulated other comprehensive income (CTA); an increase of $1,712 in goodwill; and a decrease of $288 in deferred tax liabilities.  The correction of the historical remeasurement of certain foreign cash balances resulted in $333 of additional expense ($222, net of tax) included in other income (expense) on the Consolidated Statement of Income.  Additional tax accounting related corrections resulted in additional income tax expense of $801 and adjustments to the Consolidated Balance Sheet including: a decrease of $1,104 in deferred tax liabilities; a decrease of $64 in deferred tax assets; a decrease of $891 in income tax receivable; and an increase of $950 in CTA.  Collectively, these adjustments reduced net income for fiscal 2012 by $1,195 and diluted earnings per share by approximately $0.05.
	The results of operations for the fiscal year ended September 30, 2011 include certain adjustments to correct prior period amounts, which we have determined to be immaterial to the current period and the prior periods to which they relate.  Adjustments in fiscal 2011 listed below related to: (1) $1,474 ($1,014, net of tax) in employer-paid fringe benefits for required contributions to our 401(k) Plan, Supplemental Employee Retirement Plan, and non-United States statutory pension plans as a result of our annual payment pursuant to our fiscal 2010 annual incentive cash bonus program (AIP); (2) income tax expense of $671 recorded for certain compensation in fiscal 2008 through 2010 for which a previous tax benefit should not have been recorded; (3) the reversal of a $497 deferred tax asset regarding certain share-based compensation expense which is not subject to such tax treatment; (4) our under-accrual of $290 ($199, net of tax) for payments made pursuant to the AIP as a result of the calculation of results against goals under the AIP; and (5) other immaterial corrections to deferred tax assets and liabilities that reduced our income tax expense by $101.  Collectively, these adjustments reduced net income for fiscal 2011 by $2,280 and diluted earnings per share by approximately $0.10.

SUMMARY_OF_SIGNIFICANT_ACCOUNT

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES	12 Months Ended
	Sep. 30, 2013
SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES [Abstract]	'
SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES	'
	2.SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES
	PRINCIPLES OF CONSOLIDATION
	The consolidated financial statements include the accounts of Cabot Microelectronics and its subsidiaries.  All intercompany transactions and balances between the companies have been eliminated as of September 30, 2013.
	USE OF ESTIMATES
	The preparation of financial statements and related disclosures in conformity with accounting principles generally accepted in the United States of America requires management to make judgments, assumptions and estimates that affect the amounts reported in the consolidated financial statements and accompanying notes.  The accounting estimates that require management's most difficult and subjective judgments include, but are not limited to, those estimates related to bad debt expense, warranty obligations, inventory valuation, valuation and classification of auction rate securities, impairment of long-lived assets and investments, business combinations, goodwill, other intangible assets, share-based compensation, income taxes and contingencies.  We base our estimates on historical experience, current conditions and on various other assumptions that we believe are reasonable under the circumstances.  However, future events are subject to change and estimates and judgments routinely require adjustment.  Actual results may differ from these estimates under different assumptions or conditions.
	CASH, CASH EQUIVALENTS AND SHORT-TERM INVESTMENTS
	We consider investments in all highly liquid financial instruments with original maturities of three months or less to be cash equivalents.  Short-term investments include securities generally having maturities of 90 days to one year.  We did not own any securities that were considered short-term as of September 30, 2013 or 2012.  See Note 3 for a more detailed discussion of other financial instruments.
	ACCOUNTS RECEIVABLE AND ALLOWANCE FOR DOUBTFUL ACCOUNTS
	Trade accounts receivable are recorded at the invoiced amount and do not bear interest.  We maintain an allowance for doubtful accounts for estimated losses resulting from the potential inability of our customers to make required payments.  Our allowance for doubtful accounts is based on historical collection experience, adjusted for any specific known conditions or circumstances such as customer bankruptcies and increased risk due to economic conditions.  Uncollectible account balances are charged against the allowance when we believe that it is probable that the receivable will not be recovered.
	Accounts receivable, net of allowances for doubtful accounts, was $54,640 as of September 30, 2013 and $53,506 as of September 30, 2012.  In fiscal 2012, we recorded $3,727 in bad debt expense for Elpida Memory, Inc. (Elpida), a significant customer in Japan that filed bankruptcy protection in February 2012.  Elpida has paid the Company on a current basis for all shipments made subsequent to its bankruptcy filing, and pursuant to its bankruptcy plan, will pay us approximately 17% of the balance owed over a period of seven years.    Consequently, we charged off approximately 83% of the Elpida accounts receivable balance against the related allowance for doubtful accounts during the fourth quarter of fiscal 2013.  Amounts charged to expense are recorded in general and administrative expenses.  A portion of our receivables and the related allowance for doubtful accounts is denominated in foreign currencies, so they are subject to forein exchange fluctuations which are included in the table below under the deductions and adjustments.
	Our allowance for doubtful accounts changed during the fiscal year ended September 30, 2013 as follows:		$	4,757
	Balance as of September 30, 2012
	Amounts charged to expense			173
	Deductions and adjustments			(3,398	)
	Balance as of September 30, 2013		$	1,532
	CONCENTRATION OF CREDIT RISK
	Financial instruments that subject us to concentrations of credit risk consist principally of accounts receivable.  We perform ongoing credit evaluations of our customers' financial conditions and generally do not require collateral to secure accounts receivable.  Our exposure to credit risk associated with nonpayment is affected principally by conditions or occurrences within the semiconductor industry and global economy.  Prior to the Elpida bankruptcy in fiscal 2012, we had not experienced significant losses relating to accounts receivable from individual customers or groups of customers.
	Customers who represented more than 10% of revenue are as follows:
			Year Ended September 30,
			2013			2012			2011
	Taiwan Semiconductor Manufacturing Co. (TSMC)			21	%		18	%		17	%
	Samsung			13	%		13	%		10	%
	TSMC accounted for 16.7% and 17.1% of net accounts receivable at September 30, 2013 and 2012, respectively.  Samsung accounted for 11.8% and 12.1% of net accounts receivable at September 30, 2013 and 2012, respectively.
	FAIR VALUES OF FINANCIAL INSTRUMENTS
	The recorded amounts of cash, accounts receivable, and accounts payable approximate their fair values due to their short-term, highly liquid characteristics.  The fair value of our long-term auction rate securities (ARS) is determined through discounted cash flow analyses.  See Note 3 for a more detailed discussion of the fair value of financial instruments.
	INVENTORIES
	Inventories are stated at the lower of cost, determined on the first-in, first-out (FIFO) basis, or market.  Finished goods and work in process inventories include material, labor and manufacturing overhead costs.  We regularly review and write down the value of inventory as required for estimated obsolescence or lack of marketability.  An inventory reserve is maintained based upon a historical percentage of actual inventories written off and applied against inventory value at the end of the period, adjusted for known conditions and circumstances.
	PROPERTY, PLANT AND EQUIPMENT
	Property, plant and equipment are recorded at cost.  Depreciation is based on the following estimated useful lives of the assets using the straight-line method:
	Buildings	15-25 years
	Machinery and equipment	3-10 years
	Furniture and fixtures	5-10 years
	Information systems	3-5 years
	Assets under capital leases	Lesser of term of lease or estimated useful life
	Expenditures for repairs and maintenance are charged to expense as incurred.  Expenditures for major renewals and betterments are capitalized and depreciated over the remaining useful lives.  As assets are retired or sold, the related cost and accumulated depreciation are removed from the accounts and any resulting gain or loss is included in the results of operations.  We capitalize the costs related to the design and development of software used for internal purposes; however, these costs are not material.
	IMPAIRMENT OF LONG-LIVED ASSETS
	Reviews are regularly performed to determine whether facts and circumstances exist that indicate the carrying amount of assets may not be recoverable or the useful life is shorter than originally estimated.  Asset recoverability assessment begins by comparing the projected undiscounted cash flows associated with the related asset or group of assets over their remaining lives against their respective carrying amounts.  Impairment, if any, is based on the excess of the carrying amount over the fair value of those assets.  If assets are determined to be recoverable, but their useful lives are shorter than originally estimated, the net book value of the asset is depreciated over the newly determined remaining useful life.
	GOODWILL AND INTANGIBLE ASSETS
	We amortize intangible assets with finite lives over their estimated useful lives, which range from one to ten and one half  years.  Intangible assets with finite lives are reviewed for impairment using a process similar to that used to evaluate other long-lived assets.  Goodwill and indefinite lived intangible assets are not amortized and are tested annually in the fourth fiscal quarter or more frequently if indicators of potential impairment exist, using a fair-value-based approach.  The recoverability of goodwill is measured at the reporting unit level, which is defined as either an operating segment or one level below an operating segment, referred to as a component.  A component is a reporting unit when the component constitutes a business for which discreet financial information is available and segment management regularly reviews the operating results of the component.  Components may be combined into one reporting unit when they have similar economic characteristics.  We had three reporting units to which we allocated goodwill and intangible assets as of September 30, 2013.  Goodwill impairment testing requires a comparison of the fair value of each reporting unit to the carrying value.  If the carrying value exceeds fair value, goodwill is considered impaired.  The amount of the impairment is the difference between the carrying value of goodwill and the "implied" fair value.  The fair value of the reporting unit may be determined using a discounted cash flow analysis of our projected future results.  An entity has the option to assess qualitative factors to determine if the two-step impairment test must be performed.  We elected to perform a discounted cash flow analysis in fiscal 2013 when we performed our annual impairment review of goodwill.  An entity also has the option to assess qualitative factors in its impairment review of indefinite-lived intangible assets.  However, we elected to use the royalty savings method in fiscal 2013 when we performed our impairment review of our indefinite-lived intangible assets.  We determined that goodwill and other intangible assets were not impaired as of September 30, 2013.
	WARRANTY RESERVE
	We maintain a warranty reserve that reflects management's best estimate of the cost to replace product that does not meet our specifications and customers' performance requirements.  The warranty reserve is based upon a historical product return rate, adjusted for any specific known conditions or circumstances.  Adjustments to the warranty reserve are recorded in cost of goods sold.
	FOREIGN CURRENCY TRANSLATION
	Certain operating activities in Asia and Europe are denominated in local currency, considered to be the functional currency.  Assets and liabilities of these operations are translated using exchange rates in effect at the end of the year, and revenue and costs are translated using weighted-average exchange rates for the year.  The related translation adjustments are reported in comprehensive income in stockholders' equity.
	FOREIGN EXCHANGE MANAGEMENT
	We transact business in various foreign currencies, primarily the Japanese yen, the New Taiwan dollar and Korean won.  Our exposure to foreign currency exchange risks has not been significant because a large portion of our business is denominated in U.S. dollars.  However, there was a significant weakening of the Japanese yen against the U.S. dollar during fiscal 2013, which had some positive impact on our results of operations.  Periodically we enter into forward foreign exchange contracts in an effort to mitigate the risks associated with currency fluctuations on certain foreign currency balance sheet exposures.  Our foreign exchange contracts do not qualify for hedge accounting under the accounting rules for derivative instruments.  See Note 10 for a more detailed discussion of derivative financial instruments.
	INTERCOMPANY LOAN ACCOUNTING
	We maintain intercompany loan agreements with our wholly-owned subsidiary, Nihon Cabot Microelectronics K.K. ("the K.K."), under which we provided funds to the K.K. to finance the purchase of certain assets from our former Japanese branch at the time of the establishment of this subsidiary, for the purchase of land adjacent to our Geino, Japan, facility, for the construction of our Asia Pacific technology center, and for the purchase of a 300 millimeter polishing tool and related metrology equipment, all of which are part of the K.K., as well as for general business purposes.  Since settlement of the notes is expected in the foreseeable future, and our subsidiary has been consistently making timely payments on the loans, the loans are considered foreign-currency transactions.  Therefore the associated foreign exchange gains and losses are recognized as other income or expense rather than being deferred in the cumulative translation account in other comprehensive income.
	We also maintain intercompany loan agreements between some of our wholly-owned foreign subsidiaries, including from Cabot Microelectronics Singapore Pte. Ltd. and Epoch Material Co., Ltd. in Taiwan to Hanguk Cabot Microelectronics, LLC in South Korea.  These loans have provided funds for the construction and operation of our research, development and manufacturing facility in South Korea.  These loans are also considered foreign currency transactions and are accounted for in the same manner as our intercompany loans to the K.K.
	PURCHASE COMMITMENTS
	We have entered into unconditional purchase obligations, which include noncancelable purchase commitments and take-or-pay arrangements with suppliers.  We review our agreements and make an assessment of the likelihood of a shortfall in purchases and determine if it is necessary to record a liability.
	REVENUE RECOGNITION
	Revenue from CMP consumable products is recognized when title is transferred to the customer, assuming all revenue recognition criteria are met.  Title transfer generally occurs upon shipment to the customer or when inventory held on consignment is consumed by the customer, subject to the terms and conditions of the particular customer arrangement.  We have consignment agreements with a number of our customers that require, at a minimum, monthly consumption reports that enable us to record revenue and inventory usage in the appropriate period.
	We market our products through distributors in a few areas of the world.  We recognize revenue upon shipment and when title is transferred to the distributor.  We do not have any arrangements with distributors that include payment terms, rights of return, or rights of exchange outside the normal course of business, or any other significant matters that we believe would impact the timing of revenue recognition.
	Within our Engineered Surface Finishes (ESF) business, sales of equipment are recorded as revenue upon delivery and customer acceptance.  Amounts allocated to installation and training are deferred until those services are provided and are not material.
	Revenues are reported net of any value-added tax or other such tax assessed by a governmental authority on our revenue-producing activities.
	SHIPPING AND HANDLING
	Costs related to shipping and handling are included in cost of goods sold.
	RESEARCH, DEVELOPMENT AND TECHNICAL
	Research, development and technical costs are expensed as incurred and consist primarily of staffing costs, materials and supplies, depreciation, utilities and other facilities costs.
	INCOME TAXES
	Current income taxes are determined based on estimated taxes payable or refundable on tax returns for the current year.  Deferred income taxes are determined using enacted tax rates for the effect of temporary differences between the book and tax bases of recorded assets and liabilities.  The effect on deferred tax assets and liabilities of a change in tax rates is recognized in income in the period that includes the enactment date.  Provisions are made for both U.S. and any foreign deferred income tax liability or benefit.  We recognize the tax benefit of an uncertain tax position only if it is more likely than not that the tax position will be sustained by the taxing authorities, based on the technical merits of the position.  In fiscal 2012 and 2011, we elected to permanently reinvest the earnings of certain of our foreign subsidiaries outside the U.S. rather than repatriating the earnings to the U.S.  In fiscal 2013, we elected to permanently reinvest the earnings of all of our foreign subsidiaries.  See Note 15 for additional information on income taxes.
	SHARE-BASED COMPENSATION
	We record share-based compensation expense for all share-based awards, including stock option grants, restricted stock and restricted stock unit awards and employee stock purchases.  We calculate share-based compensation expense using the straight-line approach based on awards ultimately expected to vest, which requires the use of an estimated forfeiture rate.  Our estimated forfeiture rate is primarily based on historical experience, but may be revised in future periods if actual forfeitures differ from the estimate.  We use the Black-Scholes option-pricing model to estimate the grant date fair value of our stock options and employee stock purchase plan purchases.  This model requires the input of highly subjective assumptions, including the price volatility of the underlying stock, the expected term of our stock options and the risk-free interest rate.  We estimate the expected volatility of our stock options based on a combination of our stock's historical volatility and the implied volatilities from actively-traded options on our stock.  We calculate the expected term of our stock options using historical stock option exercise data, and we add a slight premium to this expected term for employees who meet the definition of retirement eligible pursuant to their grants during the contractual term of the grant.  The risk-free rate is derived from the U.S. Treasury yield curve in effect at the time of grant.
The fair value of our restricted stock and restricted stock unit awards represents the closing price of our common stock on the date of award.
For additional information regarding our share-based compensation plans, refer to Note 11.
EARNINGS PER SHARE
Basic earnings per share (EPS) is calculated by dividing net income available to common stockholders by the weighted-average number of common shares outstanding during the period, excluding the effects of unvested restricted stock awards with a right to receive non-forfeitable dividends, which are considered participating securities as prescribed by the two class method under ASC Topic 260, Earnings Per Share (ASC 260).  Diluted EPS is calculated in a similar manner, but the weighted-average number of common shares outstanding during the period is increased to include the weighted-average dilutive effect of "in-the-money" stock options and unvested restricted stock shares using the treasury stock method.
COMPREHENSIVE INCOME
Comprehensive income primarily differs from net income due to foreign currency translation adjustments.
EFFECTS OF RECENT ACCOUNTING PRONOUNCEMENTS
In June 2011, the FASB issued ASU No. 2011-05, "Comprehensive Income (Topic 220) – Presentation of Comprehensive Income" (ASU 2011-05).  The provisions of ASU 2011-05 require an entity to present the total of comprehensive income, the components of net income, and the components of other comprehensive income either in a single continuous statement of comprehensive income or in two separate but consecutive statements.  If two separate statements are presented, the statement of other comprehensive income should immediately follow the statement of net income.  ASU 2011-05 became effective for us in the quarter ended December 31, 2012.  The adoption of ASU 2011-05 changed the way we present comprehensive income as we now present comprehensive income in a separate statement immediately following the statement of net income rather than the prior annual presentation of comprehensive income within the statement of equity and quarterly presentation of comprehensive income within the footnotes to the financial statements.
In February 2013, the FASB issued ASU No. 2013-02, "Comprehensive Income (Topic 220) – Reporting of Amounts Reclassified Out of Accumulated Other Comprehensive Income" (ASU 2013-02).  The provisions of ASU 2013-02 require an entity to provide information about the amounts reclassified out of accumulated other comprehensive income by component.  An entity is also required to present, either on the face of the statement where net income is presented or in the notes, significant amounts reclassified by the respective line items of net income if the amount reclassified is required under U.S. GAAP to be reclassified to net income in its entirety in the same reporting period.  For other amounts not required by U.S. GAAP to be reclassified to net income in their entirety, an entity is required to cross reference to other disclosures required under U.S. GAAP.  ASU 2013-02 became effective for us in the quarter ended March 31, 2013.  The adoption of ASU 2013-02 had no material impact on our financial statements as we did not have any material reclassification adjustments out of accumulated other comprehensive income.
In July 2013, the FASB issued ASU No. 2013-11, "Income Taxes (Topic 740) – Presentation of an Unrecognized Tax Benefit When a Net Operating Loss Carryforward, a Similar Tax Loss, or a Tax Credit Carryforward Exists" (ASU 2013-11).  The provisions of ASU 2013-11 require an entity to present an unrecognized tax benefit, or a portion of an unrecognized tax benefit, as a reduction to a deferred tax asset for a net operating loss carryforward, a similar tax loss, or a tax credit carryforward when the related deferred tax asset is available to be utilized.  ASU 2013-11 is effective for us beginning October 1, 2014.  We do not expect the adoption of ASU 2013-11 will have a material impact on our financial statements.

FAIR_VALUE_OF_FINANCIAL_INSTRU

FAIR VALUE OF FINANCIAL INSTRUMENTS	12 Months Ended
	Sep. 30, 2013
FAIR VALUE OF FINANCIAL INSTRUMENTS [Abstract]	'
FAIR VALUE OF FINANCIAL INSTRUMENTS	'
	3. FAIR VALUE OF FINANCIAL INSTRUMENTS
	Fair value is defined as the price that would be received from the sale of an asset or paid to transfer a liability (an exit price) in the principal or most advantageous market for the asset or liability in an orderly transaction between market participants on the measurement date.  The FASB established a three-level hierarchy for disclosure based on the extent and level of judgment used to estimate fair value.  Level 1 inputs consist of valuations based on quoted market prices in active markets for identical assets or liabilities.  Level 2 inputs consist of valuations based on quoted prices for similar assets or liabilities, quoted prices for identical assets or liabilities in an inactive market, or other observable inputs.  Level 3 inputs consist of valuations based on unobservable inputs that are supported by little or no market activity.
	The following tables present financial instruments, other than long-term debt, that we measured at fair value on a recurring basis at September 30, 2013 and 2012.  See Note 9 for a detailed discussion of our long-term debt.  We have chosen to not measure any of our other financial instruments at fair value as we believe their carrying value approximates their fair value.  We have classified the following assets in accordance with the fair value hierarchy set forth in the applicable standards.  In instances where the inputs used to measure the fair value of an asset fall into more than one level of the hierarchy, we have classified them based on the lowest level input that is significant to the determination of the fair value.
		Level 1			Level 2		Level 3		Total
	30-Sep-13								Fair Value
	Cash and cash equivalents	$	226,029		$	-	$	-	$	226,029
	Auction rate securities (ARS)		-			-		7,966		7,966
	Other long-term investments		1,375			-		-		1,375
	Total	$	227,404		$	-	$	7,966	$	235,370
		Level 1			Level 2		Level 3		Total
	30-Sep-12								Fair Value
	Cash and cash equivalents	$	178,459		$	-	$	-	$	178,459
	Auction rate securities (ARS)		-			-		7,991		7,991
	Other long-term investments		1,082			-		-		1,082
	Total	$	179,541		$	-	$	7,991	$	187,532
	Our cash and cash equivalents consist of various bank accounts used to support our operations and investments in institutional money-market funds which are traded in active markets.  The ARS and other long-term investments are included in other long-term assets on our Consolidated Balance Sheet.  The fair value of our long-term ARS is determined through two discounted cash flow analyses, one using a discount rate based on a market index comprised of tax exempt variable rate demand obligations and one using a discount rate based on the LIBOR swap curve, adding a risk factor to reflect current liquidity issues in the ARS market.  Our other long-term investments represent the fair value of investments under the Cabot Microelectronics Supplemental Employee Retirement Plan (SERP), which is a nonqualified supplemental savings plan.  The fair value of the investments is determined through quoted market prices within actively traded markets.  Although the investments are allocated to individual participants and investment decisions are made solely by those participants, the SERP has been deemed a nonqualified plan.  Consequently, the Company owns the assets and the related liability for disbursement until such time a participant makes a qualifying withdrawal.  The long-term asset and long-term liability were adjusted to $1,375 in the fourth quarter of fiscal 2013 to reflect their fair value as of September 30, 2013.
	We applied accounting standards regarding the classification and valuation of financial instruments to the valuation of our investment in ARS at September 30, 2013 and 2012.  Our ARS investments at September 30, 2013 consisted of two tax exempt municipal debt securities with a total par value of $8,200.  The ARS market began to experience illiquidity in early 2008, and this illiquidity continues.  Despite this lack of liquidity, there have been no defaults in payment of the underlying securities and interest income on these holdings continues to be received on scheduled interest payment dates.  Our ARS, when purchased, were generally issued by A-rated municipalities.  Although the credit ratings of both municipalities have been downgraded since our original investment, the ARS are credit enhanced with bond insurance and currently carry a credit rating of AA- by Standard and Poors.
	Since an active market for ARS does not currently exist, we determine the fair value of these investments using a Level 3 discounted cash flow analysis and also consider other factors such as the reduced liquidity in the ARS market and nature of the insurance backing.  Key inputs to our discounted cash flow model include projected cash flows from interest and principal payments and the weighted probabilities of improved liquidity or debt refinancing by the issuer.  We also incorporate certain Level 2 market indices into the discounted cash flow analysis, including published rates such as the LIBOR rate, the LIBOR swap curve and a municipal swap index published by the Securities Industry and Financial Markets Association.
	The following table presents a reconciliation of the activity in fiscal 2013 for fair value measurements using level 3 inputs:
	Balance as of September 30, 2012	$	7,991
	Sales of ARS		(25	)
	Balance as of September 30, 2013	$	7,966
	Based on our fair value assessment, we determined that one ARS continues to be impaired as of September 30, 2013.  This security has a fair value of $3,016 (par value $3,250).  We assessed the impairment in accordance with the applicable standards and determined that the impairment was due to the lack of liquidity in the ARS market rather than to credit risk.  We have maintained the $234 temporary impairment that we previously recorded.  We believe that this ARS is not permanently impaired because in the event of default in payment by the issuer, we expect the insurance provider would pay interest and principal following the original repayment schedule, we successfully monetized at par value $25 of this security during our fiscal quarter ended March 31, 2013 and we do not intend to sell the security nor do we believe we will be required to sell the security before the value recovers, which may be at maturity.  We determined that the fair value of the other ARS was not impaired as of September 30, 2013.  In November 2011, the municipality that issued our impaired ARS filed for bankruptcy protection.  We considered these developments, in light of the continued insurance backing, and have concluded the impairment we have maintained remains adequate and temporary.  See Note 7 for more information on these investments.

INVENTORIES

INVENTORIES	12 Months Ended
	Sep. 30, 2013
INVENTORIES [Abstract]	'
INVENTORIES	'
	4. INVENTORIES
	Inventories consisted of the following:
		September 30,
		2013		2012
	Raw materials	$	38,004	$	34,591
	Work in process		5,001		6,333
	Finished goods		20,781		25,548
	Total	$	63,786	$	66,472
	The increase in our raw materials balance at September 30, 2013 was primarily due to raw material purchases associated with a new supply agreement with an existing supplier.  The decrease in our finished goods balance at September 30, 2013 was primarily due to the increase is sales we experienced during the fourth quarter of fiscal 2013.

PROPERTY_PLANT_AND_EQUIPMENT

PROPERTY, PLANT AND EQUIPMENT	12 Months Ended
	Sep. 30, 2013
PROPERTY, PLANT AND EQUIPMENT [Abstract]	'
PROPERTY, PLANT AND EQUIPMENT	'
	5. PROPERTY, PLANT AND EQUIPMENT
	Property, plant and equipment consisted of the following:
		September 30,
		2013			2012
	Land	$	18,914		$	21,566
	Buildings		97,542			101,627
	Machinery and equipment		175,406			181,117
	Furniture and fixtures		6,234			6,417
	Information systems		26,208			25,346
	Capital leases		-			66
	Construction in progress		5,072			4,890
	Total property, plant and equipment		329,376			341,029
	Less: accumulated depreciation and amortization of assets under capital leases		(217,391	)		(216,009	)
	Net property, plant and equipment	$	111,985		$	125,020
	Depreciation expense, including amortization of assets recorded under capital leases, was $17,835, $20,863 and $21,271 for the years ended September 30, 2013, 2012 and 2011, respectively.
	In fiscal 2012, we recorded $968 in impairment expense primarily related to the decision to write-off certain operational assets at one of our foreign locations in accordance with the applicable accounting standards for the impairment and disposal of long-lived assets.  Of this amount, $842 and $126 was included in cost of goods sold and selling and marketing expense, respectively.  Impairment expense for fiscal 2013 and 2011 was not material.

GOODWILL_AND_OTHER_INTANGIBLE_

GOODWILL AND OTHER INTANGIBLE ASSETS	12 Months Ended
	Sep. 30, 2013
GOODWILL AND OTHER INTANGIBLE ASSETS [Abstract]	'
GOODWILL AND OTHER INTANGIBLE ASSETS	'
	6.  GOODWILL AND OTHER INTANGIBLE ASSETS
	Goodwill was $44,306 and $44,620 as of September 30, 2013 and 2012, respectively.  The decrease in goodwill was due to foreign exchange fluctuations of the New Taiwan dollar.
	The components of other intangible assets are as follows:
		30-Sep-13				30-Sep-12
		Gross Carrying		Accumulated		Gross Carrying		Accumulated
		Amount		Amortization		Amount		Amortization
	Other intangible assets subject to amortization:
	Product technology	$	8,362	$	5,853	$	8,387	$	4,902
	Acquired patents and licenses		8,270		7,196		8,270		6,775
	Trade secrets and know-how		2,550		2,550		2,550		2,550
	Customer relationships, distribution rights and other		12,496		7,484		12,586		6,283
	Total other intangible assets subject to amortization		31,678		23,083		31,793		20,510
	Total other intangible assets not subject to amortization*		1,190				1,190
	Total other intangible assets	$	32,868	$	23,083	$	32,983	$	20,510
	* Total other intangible assets not subject to amortization primarily consist of trade names.
	In fiscal 2013, other intangible assets decreased by $115 due to foreign exchange fluctuations of the New Taiwan dollar.  In fiscal 2012, we acquired $155 in other intangible assets, and other intangible assets increased by $553 due to foreign exchange fluctuations of the New Taiwan dollar.
	.
	Amortization expense was $2,622, $2,682 and $2,720 for fiscal 2013, 2012 and 2011, respectively.  Estimated future amortization expense for the five succeeding fiscal years is as follows:
		Estimated Amortization
		Expense
	Fiscal Year
	2014	$	2,497
	2015		2,429
	2016		2,009
	2017		1,177
	2018		466
	Goodwill and indefinite-lived intangible assets are tested for impairment annually in the fourth fiscal quarter or more frequently if indicators of potential impairment exist, using a fair-value-based approach.  The recoverability of goodwill is measured at the reporting unit level, which is defined as either an operating segment or one level below an operating segment.  Prior to fiscal 2011, we determined the fair value of our reporting units using a discounted cash flow analysis ("step one") of our projected future results.  Effective September 30, 2011, we adopted new accounting pronouncements related to our goodwill impairment analysis.  The new accounting guidance allows an entity to first assess qualitative factors to determine if it is more likely than not that the fair value of a reporting unit is less than its carrying amount ("step zero" assessment).  In fiscal 2012 and 2011, we used this guidance in our annual impairment analysis for goodwill.  In fiscal 2012, we adopted new accounting pronouncements related to our impairment review of indefinite-lived intangible assets, which allows a qualitative assessment of factors used in the impairment review.  We chose to refresh our step one analysis in fiscal 2013 for both goodwill impairment and for indefinite-lived intangible asset impairment.  Changes in economic and operating conditions that occur after the annual impairment analysis or an interim impairment analysis that impact our assumptions may result in future impairment charges.  As a result of the review performed in the fourth quarter of fiscal 2013, we determined that there was no impairment of our goodwill and intangible assets as of September 30, 2013.

OTHER_LONGTERM_ASSETS

OTHER LONG-TERM ASSETS	12 Months Ended
	Sep. 30, 2013
OTHER LONG-TERM ASSETS [Abstract]	'
OTHER LONG-TERM ASSETS	'
	7.  OTHER LONG-TERM ASSETS
	Other long-term assets consisted of the following:
		September 30,
		2013		2012
	Auction rate securities	$	7,966	$	7,991
	Other long-term assets		3,086		2,872
	Other long-term investments		1,375		1,082
	Total	$	12,427	$	11,945
	As discussed in Note 3 of this Form 10-K, the two ARS that we owned as of September 30, 2013 are classified as long-term investments.  The securities are credit enhanced with bond insurance to an AA- credit rating and all interest payments continue to be received on a timely basis.  Although we believe these securities will ultimately be collected in full, we believe that it is not likely that we will be able to monetize the securities in our next business cycle, which for us is generally one year.  We maintain a $234 pretax reduction ($151 net of tax) in fair value on one of the ARS that we first recognized in fiscal 2008.  We continue to believe this decline in fair value is temporary based on: (1) the nature of the underlying debt; (2) the presence of bond insurance; (3) the fact that all interest payments have been received; (4) our successful monetization of $25 of this ARS during the quarter ended March 31, 2013; and (5) our intention not to sell the security nor be required to sell the security until the value recovers, which may be at maturity, given our current cash position, our expected future cash flow, and our unused debt capacity.
	As discussed in Note 3 of this Form 10-K, we recorded a long-term asset and a corresponding long-term liability of $1,375 representing the fair value of our SERP investments as of September 30, 2013.

ACCRUED_EXPENSES_INCOME_TAXES_

ACCRUED EXPENSES, INCOME TAXES PAYABLE AND OTHER CURRENT LIABILITIES	12 Months Ended
	Sep. 30, 2013
ACCRUED EXPENSES, INCOME TAXES PAYABLE AND OTHER CURRENT LIABILITIES [Abstract]	'
ACCRUED EXPENSES, INCOME TAXES PAYABLE AND OTHER CURRENT LIABILITIES	'
	8.  ACCRUED EXPENSES, INCOME TAXES PAYABLE AND OTHER CURRENT LIABILITIES
	Accrued expenses, income taxes payable and other current liabilities consisted of the following:
		September 30,
		2013		2012
	Accrued compensation	$	24,601	$	18,532
	Goods and services received, not yet invoiced		4,681		3,478
	Deferred revenue and customer advances		458		3,341
	Warranty accrual		324		359
	Income taxes payable		6,931		2,843
	Taxes, other than income taxes		951		1,041
	Other		1,953		3,144
	Total	$	39,899	$	32,738
	The increase in accrued compensation was primarily related to accruals of our fiscal 2013 AIP.

DEBT

DEBT	12 Months Ended
	Sep. 30, 2013
DEBT [Abstract]	'
DEBT	'
	9. DEBT
	On February 13, 2012, we entered into a credit agreement (the "Credit Agreement") among the Company, as Borrower, Bank of America, N.A., as administrative agent, swing line lender and an L/C issuer, Bank of America Merrill Lynch and J.P. Morgan Securities LLC, as joint lead arrangers and joint book managers, JPMorgan Chase Bank, N.A., as syndication agent, and Wells Fargo Bank, N.A. as documentation agent.  The Credit Agreement provided us with a $175,000 term loan (the "Term Loan"), which we drew on February 27, 2012 to fund approximately half of the special cash dividend we paid to our stockholders on March 1, 2012, and a $100,000 revolving credit facility (the "Revolving Credit Facility"), which remains undrawn, with sub-limits for multicurrency borrowings, letters of credit and swing-line loans.  The Term Loan and the Revolving Credit Facility are referred to as the "Credit Facilities."  The Credit Agreement provides for an uncommitted accordion feature that allows us to request the existing lenders or, if necessary, third-party financial institutions to provide additional capacity in the Revolving Credit Facility, in an amount not to exceed $75,000.  The Term Loan has periodic scheduled principal repayments; however, we may prepay the loan without penalty.  The Credit Facilities are scheduled to expire on February 13, 2017.
	Borrowings under the Credit Facilities (other than in respect of swing-line loans) bear interest at a rate per annum equal to the "Applicable Rate" (as defined below) plus, at our option, either (1) a LIBOR rate determined by reference to the cost of funds for deposits in the relevant currency for the interest period relevant to such borrowing or (2) the "Base Rate", which is the highest of (x) the prime rate of Bank of America, N.A., (y) the federal funds rate plus 1/2 of 1.00% and (z) the one-month LIBOR rate plus 1.00%.  The initial Applicable Rate for borrowings under the Credit Facilities was 1.75% with respect to LIBOR borrowings and 0.25% with respect to Base Rate borrowings, with such Applicable Rate subject to adjustment based on our consolidated leverage ratio.  Swing-line loans bear interest at the Base Rate plus the Applicable Rate for Base Rate loans under the Revolving Credit Facility.  In addition to paying interest on outstanding principal under the Credit Agreement, we pay a commitment fee to the lenders under the Revolving Credit Facility in respect of the unutilized commitments thereunder at a rate ranging from 0.25% to 0.35%, based on our consolidated leverage ratio.  Interest expense and commitment fees are paid according to the relevant interest period and no less frequently than at the end of each calendar quarter.  We paid $2,658 in customary arrangement fees, upfront fees and administration fees, of which $537 and $1,273 remains in prepaid expenses and other current assets and other long-term assets, respectively, on our Consolidated Balance Sheet as of September 30, 2013.  We must also pay letter of credit fees as necessary.  We may voluntarily prepay the Credit Facilities without premium or penalty, subject to customary "breakage" fees and reemployment costs in the case of LIBOR borrowings.  All obligations under the Credit Agreement are guaranteed by each of our existing and future direct and indirect domestic subsidiaries (the "Guarantors").  The obligations under the Credit Agreement and guarantees of those obligations are secured, subject to certain exceptions, by first priority liens and security interests in the assets of the Company and its domestic subsidiaries.
	The Credit Agreement contains covenants that restrict the ability of the Company and its subsidiaries to take certain actions, including, among other things and subject to certain significant exceptions: creating liens, incurring indebtedness, making investments, engaging in mergers, selling property, paying dividends or amending organizational documents.  The Credit Agreement requires us to comply with certain financial ratio maintenance covenants, including a maximum consolidated leverage ratio of 2.75 to 1.00 through June 30, 2014 and a minimum consolidated fixed charge coverage ratio of 1.25 to 1.00.  The maximum consolidated leverage ratio decreases to 2.50 to 1.00 from July 1, 2014 through the termination of the Credit Agreement.  As of September 30, 2013, our consolidated leverage ratio was 1.47 to 1.00 and our consolidated fixed charge coverage ratio was 4.90 to 1.00.  The Credit Agreement also contains customary affirmative covenants and events of default.  We believe we are in compliance with these covenants.
	At September 30, 2013, we believe the fair value of the Term Loan using level 2 inputs approximates its carrying value of $161,875 as the loan bears a floating market rate of interest.  As of September 30, 2013, $10,938 of the debt outstanding is classified as short term.
	Principal repayments of the Term Loan are generally made on the last calendar day of each quarter if that day is considered to be a business day.
	As of September 30, 2013, scheduled principal repayments of the Term Loan were as follows:
		Principal Repayments
	Fiscal Year
	2014	$	10,938
	2015		15,312
	2016		21,875
	2017		113,750
	Total	$	161,875

DERIVATIVE_FINANCIAL_INSTRUMEN

DERIVATIVE FINANCIAL INSTRUMENTS	12 Months Ended
	Sep. 30, 2013
DERIVATIVE FINANCIAL INSTRUMENTS [Abstract]	'
DERIVATIVE FINANCIAL INSTRUMENTS	'
	10.DERIVATIVE FINANCIAL INSTRUMENTS
	Periodically we enter into forward foreign exchange contracts in an effort to mitigate the risks associated with currency fluctuations on certain foreign currency balance sheet exposures.  Our foreign exchange contracts do not qualify for hedge accounting; therefore, the gains and losses resulting from the impact of currency exchange rate movements on our forward foreign exchange contracts are recognized as other income or expense in the accompanying consolidated income statements in the period in which the exchange rates change.  We do not use derivative financial instruments for trading or speculative purposes.  In addition, all derivatives, whether designated in hedging relationships or not, are required to be recorded on the balance sheet at fair value.  At September 30, 2013, we had one forward foreign exchange contract selling Japanese Yen related to intercompany notes with one of our subsidiaries in Japan and for the purpose of hedging the risk associated with a net transactional exposure in Japanese Yen.
	The fair value of our derivative instrument included in the Consolidated Balance Sheet, which was determined using Level 2 inputs, was as follows:
			Asset Derivatives				Liability Derivatives
	Derivatives not designated as hedging instruments		Fair Value at September 30, 2013		Fair Value at September 30, 2012		Fair Value at September 30, 2013			Fair Value at September 30, 2012
		Balance Sheet Location
	Foreign exchange contracts	Prepaid expenses and other current assets	$	60	$	38	$	-		$	-
		Accrued expenses and other current liabilities	$	-	$	-	$	-		$	-
	The following table summarizes the effect of our derivative instrument on our Consolidated Statement of Income for the fiscal years ended September 30, 2013, 2012 and 2011:
			Gain (Loss) Recognized in Statement of Income
			Fiscal Year Ended
	Derivatives not designated as hedging instruments	Statement of Income Location	30-Sep-13		30-Sep-12		30-Sep-11
	Foreign exchange contracts	Other income (expense), net	$	252	$	154	$	(806	)

SHAREBASED_COMPENSATION_PLANS

SHARE-BASED COMPENSATION PLANS	12 Months Ended
	Sep. 30, 2013
SHARE-BASED COMPENSATION PLANS [Abstract]	'
SHARE-BASED COMPENSATION PLANS	'
	11. SHARE-BASED COMPENSATION PLANS
	EQUITY INCENTIVE PLAN AND OMNIBUS INCENTIVE PLAN
	In March 2004, our stockholders approved our Second Amended and Restated Cabot Microelectronics Corporation 2000 Equity Incentive Plan (the "EIP"), as amended and restated September 23, 2008.  On March 6, 2012, our stockholders approved the 2012 Omnibus Incentive Plan (the "OIP"), which is the successor plan to the EIP.  As of such time, all share-based awards have been made from the OIP, and the EIP is no longer available for any awards.  The OIP is administered by the Compensation Committee of the Board of Directors and is intended to provide management with the flexibility to attract, retain and reward our employees, directors, consultants and advisors.  The OIP allows for the granting of six types of equity incentive awards: stock options, restricted stock, restricted stock units, stock appreciation rights (SARs), performance-based awards and substitute awards.  The OIP also provides for cash incentive awards to be made.  Substitute awards under the OIP are those awards that, in connection with an acquisition, may be granted to employees, directors, consultants or advisors of the acquired company, in substitution for equity incentives held by them in the seller or the acquired company.  No SARs, performance awards, or substitute awards have been granted to date under either plan.  No awards of any type have been granted to date to consultants or advisors under either plan.  The OIP authorizes up to 4,934,444 shares of stock to be granted thereunder, including up to 2,030,952 shares of stock in the aggregate of awards other than options or SARs, and up to 2,538,690 incentive stock options.  The 4,934,444 shares of stock represents 2,901,360 shares of newly authorized shares and 2,033,084 shares previously available under the EIP.  In addition, shares that become available from awards under the EIP and the OIP because of events such as forfeitures, cancellations or expirations, or because shares subject to an award are withheld to satisfy tax withholding obligations, will also be available for issuance under the OIP.  Shares issued under our share-based compensation plans are issued from new shares rather than from treasury shares.
	On March 2, 2012, we completed a leveraged recapitalization pursuant to which we paid a special cash dividend of $15 per share to our stockholders.  In conjunction with this recapitalization, the EIP and the OIP required us to proportionally adjust the shares available for issuance under them.  The number of shares available under the plans was increased by multiplying the number by a factor of 1.45068, representing the ratio of the official NASDAQ closing price of $51.92 per share on March 1, 2012, the dividend payment date, to the official NASDAQ opening price of $35.79 per share on March 2, 2012, the ex-dividend date.  The number of authorized shares in the OIP noted above includes the effects of this proportional adjustment.
	Non-qualified stock options issued under the OIP, as they were under the EIP, are generally time-based and provide for a ten-year term, with options generally vesting equally over a four-year period, with first vesting on the first anniversary of the award date.  Beginning in March 2011, non-qualified stock options granted to non-employee directors on an annual basis vest 100% on the first anniversary of the award date.  Compensation expense related to our stock option awards was $6,878, $6,802 and $6,871 in fiscal 2013, 2012 and 2011, respectively.  For additional information on our accounting for share-based compensation, see Note 2 to the consolidated financial statements.  Under the OIP, as under the EIP, employees may also be granted ISOs to purchase common stock at not less than the fair value on the date of the grant.  No ISOs have been granted to date under either plan.
	Under the OIP, as under the EIP, employees and non-employees may be awarded shares of restricted stock or restricted stock units, which generally vest over a four-year period, with first vesting on the anniversary of the grant date.  Beginning in March 2011, restricted stock units granted to non-employee directors on an annual basis vest 100% on the first anniversary of the award date.  In general, shares of restricted stock and restricted stock units may not be sold, assigned, transferred, pledged, disposed of or otherwise encumbered.  Holders of restricted stock, and restricted stock units, if specified in the award agreements, have all the rights of stockholders, including voting and dividend rights, subject to the above restrictions, although the current holders of restricted stock units do not have such rights.  Restricted shares under the OIP, as under the EIP, also may be purchased and placed "on deposit" by executive officers pursuant to the 2001 Deposit Share Program.  Shares purchased under this Deposit Share Program receive a 50% match in restricted shares ("Award Shares").  These Award Shares vest at the end of a three-year period, and are subject to forfeiture upon early withdrawal of the deposit shares.  Compensation expense related to our restricted stock and restricted stock unit awards and restricted shares matched at 50% pursuant to the Deposit Share Program was $5,793, $5,674 and $5,184 for fiscal 2013, 2012 and 2011, respectively.
	EMPLOYEE STOCK PURCHASE PLAN
	In March 2008, our stockholders approved our 2007 Cabot Microelectronics Employee Stock Purchase Plan (the "ESPP"), which amended the ESPP for the primary purpose of increasing the authorized shares of common stock to be purchased under the ESPP from 475,000 designated shares to 975,000 shares.  The ESPP required us to proportionally adjust the cumulative number of shares designated under the plan to reflect the effect of the leveraged recapitalization with a special cash dividend.  The cumulative number of shares designated under the ESPP was increased by a factor of 1.45068 representing the ratio of the official NASDAQ closing price of $51.92 per share on the dividend payment date, to the official NASDAQ opening price of $35.79 per share on the ex-dividend date.  As of September 30, 2013, a total of 730,023 shares are available for purchase under the ESPP.  The ESPP allows all full-time, and certain part-time, employees of our Company and its subsidiaries to purchase shares of our common stock through payroll deductions.  Employees can elect to have up to 10% of their annual earnings withheld to purchase our stock, subject to a maximum number of shares that a participant may purchase and a maximum dollar expenditure in any six-month offering period, and certain other criteria.  The provisions of the ESPP allow shares to be purchased at a price no less than the lower of 85% of the closing price at the beginning or end of each semi-annual stock purchase period.  A total of 84,602, 70,645, and 61,364 shares were issued under the ESPP during fiscal 2013, 2012 and 2011, respectively.  Compensation expense related to the ESPP was $584, $735 and $508 in fiscal 2013, 2012 and 2011, respectively.
	DIRECTORS' DEFERRED COMPENSATION PLAN
	The Directors' Deferred Compensation Plan (DDCP), as amended and restated September 23, 2008, became effective in March 2001 and applies only to our non-employee directors.  The cumulative number of shares deferred under the plan was 74,469 and 71,781 as of September 30, 2013 and 2012, respectively.  The DDCP required us to proportionally adjust the cumulative number of shares deferred under the plan to reflect the effect of the leveraged recapitalization with a special cash dividend.  The cumulative number of shares deferred under the DDCP was increased by a factor of 1.45068 representing the ratio of the official NASDAQ closing price of $51.92 per share on the dividend payment date, to the official NASDAQ opening price of $35.79 per share on the ex-dividend date.  Compensation expense related to the DDCP was $95, $95 and $83 for fiscal 2013, 2012 and 2011, respectively.
	ACCOUNTING FOR SHARE-BASED COMPENSATION
	We record share-based compensation expense for all share-based awards, including stock option grants, restricted stock and restricted stock unit awards and employee stock purchase plan purchases.  We calculate share-based compensation expense using the straight-line approach based on awards ultimately expected to vest, which requires the use of an estimated forfeiture rate.  Our estimated forfeiture rate is primarily based on historical experience, but may be revised in future periods if actual forfeitures differ from the estimate.  We use the Black-Scholes option-pricing model to estimate the grant date fair value of our stock options and employee stock purchase plan purchases.  This model requires the input of highly subjective assumptions, including the price volatility of the underlying stock, the expected term of our stock options and the risk-free interest rate.  We estimate the expected volatility of our stock options based on a combination of our stock's historical volatility and the implied volatilities from actively-traded options on our stock.  We calculate the expected term of our stock options using historical stock option exercise data, and we add a slight premium to this expected term for employees who meet the definition of retirement eligible pursuant to their grants during the contractual term of the grant.  The risk-free rate is derived from the U.S. Treasury yield curve in effect at the time of grant.
	The fair value of our share-based awards, as shown below, was estimated using the Black-Scholes model with the following weighted-average assumptions, excluding the effect of our leveraged recapitalization:
		Year Ended September 30,
		2013			2012			2011
	Stock Options
	Weighted-average grant date fair value	$	12.13		$	15.66		$	16.49
	Expected term (in years)		6.37			6.38			6.28
	Expected volatility		36	%		38	%		36	%
	Risk-free rate of return		0.9	%		1.3	%		2.1	%
	Dividend yield		-			-			-
	ESPP
	Weighted-average grant date fair value	$	7.41		$	8.78		$	9.05
	Expected term (in years)		0.5			0.5			0.5
	Expected volatility		25	%		36	%		28	%
	Risk-free rate of return		0.1	%		0.1	%		0.2	%
	Dividend yield		-			-			-
	The Black-Scholes model is primarily used in estimating the fair value of short-lived exchange traded options that have no vesting restrictions and are fully transferable.  Because employee stock options and employee stock purchase plan purchases have certain characteristics that are significantly different from traded options, and because changes in the subjective assumptions can materially affect the estimated value, our use of the Black-Scholes model for estimating the fair value of stock options and employee stock purchases may not provide an accurate measure.  Although the value of our stock options and employee stock purchase plan purchases are determined in accordance with applicable accounting standards using an option-pricing model, those values may not be indicative of the fair values observed in a willing buyer/willing seller market transaction.
	The fair value of our restricted stock and restricted stock unit awards represents the closing price of our common stock on the date of award.  Share-based compensation expense related to restricted stock and restricted stock unit awards is recorded net of expected forfeitures.
	SHARE-BASED COMPENSATION EXPENSE
	Total share-based compensation expense for the years ended September 30, 2013, 2012 and 2011, is as follows:
		Year Ended September 30, 2013,
	Income statement classifications:	2013			2012			2011
	Cost of goods sold	$	1,707		$	1,541		$	1,221
	Research, development and technical		1,301			1,105			1,060
	Selling and marketing		1,367			1,392			1,124
	General and administrative		8,975			9,268			9,241
	Tax benefit		(4,581	)		(4,118	)		(4,060	)
	Total share-based compensation expense, net of tax	$	8,769		$	9,188		$	8,586
	Our non-employee directors received annual equity awards in March 2013 at the time of our Annual Meeting of Stockholders, pursuant to the OIP.  The award agreements for non-employee directors provide for immediate vesting of the award at the time of termination of service for any reason other than by reason of Cause, Death, Disability or a Change in Control, as defined in the OIP, if at such time the non-employee director has completed an equivalent of at least two full terms as a director of the Company, as defined in the Company's bylaws.  Five of the Company's non-employee directors had completed at least two full terms of service as of the date of the March 2013 award.  Consequently, the requisite service period for the award has already been satisfied and we recorded the fair value of $755 of the awards to these five directors to share-based compensation expense in the fiscal quarter ended March 31, 2013 rather than recording that expense over the one-year vesting period stated in the award agreement, as is done for the other three non-employee directors.
	STOCK OPTION ACTIVITY
	In fiscal 2012, as required by the EIP, the exercise prices and the number of outstanding non-qualified stock options (NQSOs) were adjusted to reflect the leveraged recapitalization with a special cash dividend.  The exercise prices of outstanding NQSOs were reduced by multiplying them by a factor of 0.68933, representing the ratio of the official opening price of our common stock on the NASDAQ stock market of $35.79 per share on the ex-dividend date, to the official closing price of our common stock on the NASDAQ stock market of $51.92 per share on the last trading day immediately prior to the ex-dividend date.  The number of outstanding NQSOs was increased by multiplying the number by a factor of 1.45068, representing the ratio of the official NASDAQ closing price of $51.92 per share on the dividend payment date to the official NASDAQ opening price of $35.79 per share on the ex-dividend date.  This adjustment did not result in additional share-based compensation expense in the period as the fair value of the outstanding NQSOs immediately following the payment of the special cash dividend was equal to the fair value immediately prior to such distribution.
	A summary of stock option activity under the EIP and OIP as of September 30, 2013, and changes during the fiscal 2013 are presented below:
								Weighted
								Average
					Weighted			Remaining			Aggregate
					Average			Contractual			Intrinsic
		Stock			Exercise			Term			Value
		Options			Price			(in years)			(in thousands)
	Outstanding at September 30, 2012		5,133,626		$	26.75
	Granted		533,424			32.89
	Exercised		(1,071,750	)		26.61
	Forfeited or canceled		(321,413	)		34.72
	Outstanding at September 30, 2013		4,273,887		$	26.95			5.2		$	49,410
	Exercisable at September 30, 2013		2,881,901		$	25.82			3.7		$	36,568
	Expected to vest after September 30, 2013		1,321,760		$	29.53			8.2		$	11,870
	The aggregate intrinsic value in the table above represents the total pretax intrinsic value (i.e., for all in-the-money stock options, the difference between our closing stock price of $38.51 per share on the last trading day of fiscal 2013 and the exercise price, multiplied by the number of shares) that would have been received by the option holders had all option holders exercised their options on the last trading day of fiscal 2013.  The total intrinsic value of options exercised was $9,847, $6,879 and $13,135 for fiscal 2013, 2012 and 2011, respectively.
	The total cash received from options exercised was $28,525, $34,107 and $35,955 for fiscal 2013, 2012 and 2011, respectively.  The actual tax benefit realized for the tax deductions from options exercised was $3,394, $2,239 and $4,401 for fiscal 2013, 2012 and 2011, respectively.  The total fair value of stock options vested during fiscal years 2013, 2012 and 2011 was $6,681, $6,796 and $6,321, respectively.  As of September 30, 2013, there was $9,697 of total unrecognized share-based compensation expense related to unvested stock options granted under the EIP and OIP.  That cost is expected to be recognized over a weighted-average period of 2.4 years.
	RESTRICTED STOCK AND RESTRICTED STOCK UNITS
	Similarly, the EIP required that we adjust the number of outstanding restricted stock units (RSUs) as a result of the leveraged recapitalization with a special cash dividend.  The number of outstanding RSUs was increased by multiplying the number by a factor of 1.45068, representing the ratio of the official NASDAQ closing price of $51.92 per share on the dividend payment date to the official NASDAQ opening price of $35.79 per share on the ex-dividend date.  This adjustment did not result in additional share-based compensation expense in the period as the fair value of the outstanding RSUs immediately following the payment of the special cash dividend was equal to the fair value immediately prior to such distribution.
	A summary of the status of the restricted stock awards and restricted stock unit awards outstanding that were granted under the EIP and OIP as of September 30, 2013, and changes during fiscal 2013, are presented below:
		Restricted			Weighted
		Stock			Average
	Awards and			Grant Date
	Units			Fair Value
Nonvested at September 30, 2012		394,124		$	34.15
Granted		184,581			32.94
Vested		(174,362	)		31.3
Forfeited		(7,914	)		34.23
Nonvested at September 30, 2013		396,429		$	34.84
As of September 30, 2013, there was $8,521 of total unrecognized share-based compensation expense related to nonvested restricted stock awards and restricted stock units under the EIP and OIP.  That cost is expected to be recognized over a weighted-average period of 2.5 years.  The total fair value of restricted stock awards and restricted stock units vested during fiscal years 2013, 2012 and 2011 was $5,457, $5,784 and $4,452, respectively.

SAVINGS_PLAN

SAVINGS PLAN	12 Months Ended
	Sep. 30, 2013
SAVINGS PLAN [Abstract]	'
SAVINGS PLAN	'
	12.  SAVINGS PLAN
	Effective in May 2000, we adopted the Cabot Microelectronics Corporation 401(k) Plan (the "401(k) Plan"), which is a qualified defined contribution plan, covering all eligible U.S. employees meeting certain minimum age and eligibility requirements, as defined by the 401(k) Plan.  Participants may make elective contributions of up to 60% of their eligible compensation.  All amounts contributed by participants and earnings on these contributions are fully vested at all times.  The 401(k) Plan provides for matching and fixed non-elective contributions by the Company.  Under the 401(k) Plan, the Company will match 100% of the first four percent of the participant's eligible compensation and 50% of the next two percent of the participant's eligible compensation that is contributed, subject to limitations required by government regulations.  Under the 401(k) Plan, all U.S. employees, even those who do not contribute to the 401(k) Plan, receive a contribution by the Company in an amount equal to four percent of eligible compensation, and thus are participants in the 401(k) Plan.  Participants are 100% vested in all Company contributions at all times.  The Company's expense for the 401(k) Plan totaled $4,057, $4,210 and $4,201 for the fiscal years ended September 30, 2013, 2012 and 2011, respectively.

OTHER_INCOME_EXPENSE_NET

OTHER INCOME (EXPENSE), NET	12 Months Ended
	Sep. 30, 2013
OTHER INCOME (EXPENSE), NET [Abstract]	'
OTHER INCOME (EXPENSE), NET	'
	13.  OTHER INCOME (EXPENSE), NET
	Other income (expense), net, consisted of the following:
		Year Ended September 30,
		2013		2012			2011
	Interest income	$	145	$	146		$	238
	Other income (expense)		1,247		(1,490	)		(1,556	)
	Total other income (expense), net	$	1,392	$	(1,344	)	$	(1,318	)
	Other income (expense) primarily represents the gains and losses recorded on transactions denominated in foreign currencies.  The increase in other income in fiscal 2013 was due to the impact of foreign currency fluctuations on monetary assets and liabilities denominated in currencies other than the functional currency, primarily related to the weakening of the Japanese yen against the U.S. dollar, net of the gains and losses incurred on forward foreign exchange contracts discussed in Note 10 of this Form 10-K.  Other expense in fiscal 2012 was consistent with other expense recorded in fiscal 2011.

STOCKHOLDERS_EQUITY

STOCKHOLDERS' EQUITY	12 Months Ended
	Sep. 30, 2013
STOCKHOLDERS EQUITY [Abstract]	'
STOCKHOLDERS EQUITY	'
	14.   STOCKHOLDERS' EQUITY
	The following is a summary of our capital stock activity over the past three years:
		Number of Shares
		Common	Treasury
		Stock	Stock
	30-Sep-10	26,384,715	3,446,069
	Exercise of stock options	1,085,965
	Restricted stock under EIP, net of forfeitures	115,069
	Restricted stock under Deposit Share Plan	5,223
	Common stock under ESPP	61,364
	Repurchases of common stock under share repurchase plans		1,235,668
	Repurchases of common stock – other		33,840
	30-Sep-11	27,652,336	4,715,577
	Exercise of stock options	976,645
	Restricted stock under EIP, net of forfeitures	159,879
	Restricted stock under Deposit Share Plan, net of forfeitures	5,022
	Common stock under ESPP	70,645
	Repurchases of common stock under share repurchase plans		929,407
	Repurchases of common stock – other		37,304
	30-Sep-12	28,864,527	5,682,288
	Exercise of stock options	1,071,750
	Restricted stock under EIP and OIP, net of forfeitures	185,925
	Restricted stock under Deposit Share Plan, net of forfeitures	6,773
	Common stock under ESPP	84,602
	Repurchases of common stock under share repurchase plans		1,144,836
	Repurchases of common stock – other		39,551
	30-Sep-13	30,213,577	6,866,675
	COMMON STOCK
	Each share of common stock, including those awarded as restricted stock, but not restricted stock units, entitles the holder to one vote on all matters submitted to a vote of Cabot Microelectronics' stockholders.  Common stockholders are entitled to receive ratably the dividends, if any, as may be declared by the Board of Directors.  The number of authorized shares of common stock is 200,000,000 shares.
	SHARE REPURCHASES
	In November 2010, our Board of Directors authorized a share repurchase program for up to $125,000 of our outstanding common stock, which became effective on the authorization date.  As of December 13, 2011, we had $82,869 remaining under this share repurchase program.  In conjunction with our capital management initiative that we announced in December 2011, on December 13, 2011, our Board of Directors authorized an increase in the amount available under our share repurchase program up to $150,000.  We repurchased 1,144,836 shares for $40,000 during fiscal 2013, 929,407 shares for $33,026 during fiscal 2012, and 671,100 shares for $29,105 during fiscal 2011 under this expanded program.  As of September 30, 2013, $90,000 remains outstanding under our share repurchase program.  In fiscal 2011, we also repurchased 564,568 shares for $25,000 under a prior share repurchase program, which was completed during the quarter ended March 31, 2011.  Shares are repurchased from time to time, depending on market conditions, in open market transactions, at management's discretion.  To date, we have funded share repurchases under our share repurchase program from our existing cash balance, and anticipate we will continue to do so.  The program, which became effective on the authorization date, may be suspended or terminated at any time, at the Company's discretion.  For additional information on share repurchases, see Part II, Item 5. "Market for Registrant's Common Equity, Related Stockholder Matters and Issuer Purchases of Equity Securities".
	Separate from this share repurchase program, a total of 39,551, 37,304 and 33,840 shares were purchased during fiscal 2013, 2012 and 2011, respectively, pursuant to the terms of our EIP and OIP as shares withheld from award recipients to cover payroll taxes on the vesting of shares of restricted stock granted under the EIP and OIP.

INCOME_TAXES

INCOME TAXES	12 Months Ended
	Sep. 30, 2013
INCOME TAXES [Abstract]	'
INCOME TAXES	'
	15. INCOME TAXES
	Income before income taxes was as follows:
		Year Ended September 30,
		2013			2012			2011
	Domestic	$	40,045		$	55,555		$	54,886
	Foreign		34,175			7,316			24,026
	Total	$	74,220		$	62,871		$	78,912
	Taxes on income consisted of the following:
		Year Ended September 30,
		2013			2012			2011
	U.S. federal and state:
	Current	$	17,649		$	19,975		$	15,700
	Deferred		(3,576	)		(308	)		6,194
	Total	$	14,073		$	19,667		$	21,894
	Foreign:
	Current	$	8,304		$	5,593		$	6,616
	Deferred		458			(3,215	)		(1,260	)
	Total		8,762			2,378			5,356
	Total U.S. and foreign	$	22,835		$	22,045		$	27,250
	The provision for income taxes at our effective tax rate differed from the statutory rate as follows:
		Year Ended September 30,
		2013			2012			2011
	Federal statutory rate		35	%		35	%		35	%
	U.S. benefits from research and experimentation activities		-2	%		-0.5	%		-2	%
	State taxes, net of federal effect		0.3	%		0.2	%		0.6	%
	Foreign income at other than U.S. rates		-3.1	%		-1.9	%		-2.8	%
	Change in valuation allowance		1.4	%		1.1	%		0	%
	Executive compensation		0.2	%		0.8	%		1.4	%
	Share-based compensation		0.1	%		0.7	%		3.3	%
	Adjustment of prior amounts		-0.2	%		-0.2	%		0	%
	Domestic production deduction		-0.2	%		-0.5	%		-0.8	%
	Tax-exempt interest income		0	%		0	%		-0.1	%
	Other, net		-0.7	%		0.4	%		-0.1	%
	Provision for income taxes		30.8	%		35.1	%		34.5	%
	In fiscal  2012 and 2011, we elected to permanently reinvest the earnings of certain of our foreign subsidiaries outside the U.S. rather than repatriating the earnings to the U.S.  In fiscal 2013, we elected to permanently reinvest the earnings of all of our foreign subsidiaries.  We have not provided deferred taxes on approximately $60.3 million of undistributed earnings of such subsidiaries.  These earnings could become subject to additional income tax if they are remitted as dividends to the U.S. parent company, loaned to the U.S. parent company, or upon sale of subsidiary stock.  Determination of the amount of unrecognized deferred tax liability related to these earnings is not practicable.
	The decrease in our effective tax rate in fiscal 2013 was primarily due to the reinstatement of the U.S. research and experimentation tax credit, retroactively effective January 1, 2012, as the American Taxpayer Relief Act of 2012 was signed into law on January 2, 2013, and a $1,810 decrease in income tax expense related to our election to permanently reinvest the earnings of our subsidiaries in Japan and South Korea.  We recorded a $947 discrete income tax benefit related to fiscal 2012 research and experimentation expenses in the second quarter of fiscal 2013 and we recorded an additional $1,518 in tax benefits for full fiscal year 2013.  These decreases were partially offset by the recognition of a $1,686 foreign tax adjustment related to our net operating losses associated with our facility in South Korea, as discussed in footnote 1 of this 10-K under the heading "Results of Operations", and the recognition of a $1,015 valuation allowance on a deferred tax asset related to a past equity investment in an entity that was legally dissolved during the quarter ended March 31, 2013.  As also discussed in Note 1 of this 10-K under the heading "Results of Operations", income tax expense in fiscal 2012 included $973 of non-material adjustments to correct various prior period amounts and income tax expense in fiscal 2011 included $671 of adjustments to executive compensation in fiscal 2008 through 2010 and a $497 reversal of a deferred tax asset for certain share-based compensation expense.
	The accounting guidance regarding uncertainty in income taxes prescribes a threshold for the financial statement recognition and measurement of tax positions taken or expected to be taken on a tax return.  Under these standards, we may recognize the tax benefit of an uncertain tax position only if it is more likely than not that the tax position will be sustained by the taxing authorities, based on the technical merits of the position.
	The following table presents the changes in the balance of gross unrecognized tax benefits during the last three fiscal years:
	Balance September 30, 2010	$	173
	Additions for tax positions relating to the current fiscal year		123
	Additions for tax positions relating to prior fiscal years		307
	Settlements with taxing authorities		-
	Lapse of statute of limitations		-
	Balance September 30, 2011		603
	Additions for tax positions relating to the current fiscal year		51
	Additions for tax positions relating to prior fiscal years		114
	Settlements with taxing authorities		(353	)
	Lapse of statute of limitations		(132	)
	Balance September 30, 2012		283
	Additions for tax positions relating to the current fiscal year		228
	Additions for tax positions relating to prior fiscal years		247
	Settlements with taxing authorities		-
	Lapse of statute of limitations		-
	Balance September 30, 2013	$	758
	We recognize interest and penalties related to uncertain tax positions as income tax expense in our financial statements.  Interest and penalties accrued on our Consolidated Balance Sheet were $60 and $4 at September 30, 2013 and 2012, respectively, and interest and penalties charged to expense in fiscal years 2013, 2012 and 2011 were not material.
	We believe the tax periods open to examination by the U.S. federal government include fiscal years 2010 through 2013.  We believe the tax periods open to examination by U.S. state and local governments include fiscal years 2009 through 2013 and the tax periods open to examination by foreign jurisdictions include fiscal years 2009 through 2013.  We do not anticipate a significant change to the total amount of unrecognized tax benefits within the next 12 months.
	Significant components of net deferred tax assets and liabilities were as follows:
		September 30,
		2013			2012
	Deferred tax assets:
	Employee benefits	$	3,892		$	4,035
	Inventory		3,138			2,930
	Bad debt reserve		515			1,708
Share-based compensation expense		13,907			12,659
Net operating losses		759			2,292
Other		2,723			2,656
Valuation allowance		(2,288	)		(1,378	)
Total deferred tax assets	$	22,646		$	24,902
Deferred tax liabilities:
Translation adjustment	$	3,247		$	7,966
Depreciation and amortization		2,046			3,776
Unremitted foreign earnings		-			1,810
Other		962			645
Total deferred tax liabilities	$	6,255		$	14,197
As of September 30, 2013, the Company had foreign and state net operating loss carryforwards (NOLs) of $5,375 and $449, respectively, which will expire beginning in fiscal year 2017 through fiscal year 2032, for which we have recorded a $1,649 gross valuation allowance.  As of September 30, 2013, the Company had $1,827 in state tax credit carryforwards, for which we have recorded a $942 gross valuation allowance.  As of September 30, 2013, the Company had a capital loss carryforward of $2,849, for which we have recorded a $1,015 valuation allowance, as noted above.
The Company has been awarded a tax holiday in South Korea with respect to its manufacturing and distribution operations.  This arrangement allowas for a 0% tax in fiscal years 2013, 2014 and 2015, and a tax at 50% of the local statutory rate in effect for fiscal years 2016 and 2017.  This tax holiday reduced our fiscal 2013 income tax provision by approximately $467.

COMMITMENTS_AND_CONTINGENCIES

COMMITMENTS AND CONTINGENCIES	12 Months Ended
	Sep. 30, 2013
COMMITMENTS AND CONTINGENCIES [Abstract]	'
COMMITMENTS AND CONTINGENCIES	'
	16.  COMMITMENTS AND CONTINGENCIES
	LEGAL PROCEEDINGS
	While we are not involved in any legal proceedings that we believe will have a material impact on our consolidated financial position, results of operations or cash flows, we periodically become a party to legal proceedings in the ordinary course of business.
	PRODUCT WARRANTIES
	We maintain a warranty reserve that reflects management's best estimate of the cost to replace product that does not meet our specifications and customers' performance requirements, and costs related to such replacement.  The warranty reserve is based upon a historical product replacement rate, adjusted for any specific known conditions or circumstances.  Additions and deductions to the warranty reserve are recorded in cost of goods sold.
	Our warranty reserve requirements changed during fiscal 2013 as follows:
	Balance as of September 30, 2012	$	359
	Reserve for product warranty during the reporting period		874
	Settlement of warranty		(909	)
	Balance as of September 30, 2013	$	324
	INDEMNIFICATION
	In the normal course of business, we are a party to a variety of agreements pursuant to which we may be obligated to indemnify the other party with respect to certain matters.  Generally, these obligations arise in the context of agreements entered into by us, under which we customarily agree to hold the other party harmless against losses arising from items such as a breach of certain representations and covenants including title to assets sold, certain intellectual property rights and certain environmental matters.  These terms are common in the industries in which we conduct business.  In each of these circumstances, payment by us is subject to certain monetary and other limitations and is conditioned on the other party making an adverse claim pursuant to the procedures specified in the particular agreement, which typically allow us to challenge the other party's claims.
	We evaluate estimated losses for such indemnifications under the accounting standards related to contingencies and guarantees.  We consider such factors as the degree of probability of an unfavorable outcome and the ability to make a reasonable estimate of the amount of loss.  To date, we have not experienced material costs as a result of such obligations and, as of September 30, 2013, have not recorded any liabilities related to such indemnifications in our financial statements as we do not believe the likelihood of such obligations is probable.
	LEASE COMMITMENTS
	We lease certain vehicles, warehouse facilities, office space, machinery and equipment under cancelable and noncancelable leases, all of which expire within six years from now and may be renewed by us.  Rent expense under such arrangements during fiscal 2013, 2012 and 2011 totaled $2,594, $3,199 and $2,934, respectively.
	In December 2001 we entered into a fumed alumina supply agreement with Cabot Corporation under which we agreed to pay Cabot Corporation for the expansion of a fumed alumina manufacturing facility in Tuscola, Illinois.  The arrangement for the facility has been treated as a capital lease for accounting purposes and the present value of the minimum quarterly payments resulted in an initial $9,776 lease obligation and related leased asset.  The agreement expired in December 2011.
	Future minimum rental commitments under noncancelable leases as of September 30, 2013 are as follows:
	Fiscal Year	Operating
	2014	$	2,907
	2015		1,775
	2016		1,583
	2017		1,195
	2018		157
	Thereafter		450
		$	8,067
	PURCHASE OBLIGATIONS
	Purchase obligations include our take-or-pay arrangements with suppliers, and purchase orders and other obligations entered into in the normal course of business regarding the purchase of goods and services.
	Prior to January 1, 2013, we operated under a fumed silica supply agreement with Cabot Corporation, our former parent company which is not a related party, under which we were generally obligated to purchase at least 90% of our six-month volume forecast for certain of our slurry products, to purchase certain minimum quantities every six months, and to pay for the shortfall if we purchased less than these amounts.  This agreement expired on December 31, 2012.  We did not pay any shortfall under this agreement.  We entered into a new fumed silica supply agreement with Cabot Corporation that became effective as of January 1, 2013 with an initial term of four years.  This new agreement has revised pricing and requires us to purchase certain minimum quantities of fumed silica each year of the agreement, and to pay a shortfall if we purchase less than the minimum.  We also operated under a fumed alumina supply agreement with Cabot Corporation, which expired in April 2013, under which we were obligated to pay certain fixed, capital and variable costs, and had take-or-pay obligations.  We did not pay any shortfall under this agreement.  Purchase obligations include $110,576 of contractual commitments related to our Cabot Corporation agreements for fumed silica.
	POSTRETIREMENT OBLIGATIONS IN FOREIGN JURISDICTIONS
	We have unfunded defined benefit plans covering employees in certain foreign jurisdictions as required by local law.  Our plans in Japan, which represent the majority of our pension liability for such plans, had a projected benefit obligation of $4,843 and $5,641 as of September 30, 2013 and 2012, respectively, and an accumulated benefit obligation of $3,631 and $4,183 as of September 30, 2013 and 2012, respectively.  Key assumptions used in the actuarial measurement of the Japan pension liability include a weighted average discount rate of 1.75 % and an expected rate of compensation increase of 2.00 % at September 30, 2013 and 2012.  Total future Japan pension costs included in accumulated other comprehensive income are $665 and $672 at September 30, 2013 and 2012, respectively.  Benefit costs, consisting primarily of service costs, are recorded as fringe benefit expense under cost of goods sold and operating expenses in our Consolidated Statement of Income.  Benefit payments under all such unfunded plans to be paid over the next 10 years are expected to be immaterial.

EARNINGS_PER_SHARE

EARNINGS PER SHARE	12 Months Ended
	Sep. 30, 2013
EARNINGS PER SHARE [Abstract]	'
EARNINGS PER SHARE	'
	17. EARNINGS PER SHARE
	Basic earnings per share (EPS) is calculated by dividing net income available to common stockholders by the weighted-average number of common shares outstanding during the period, excluding the effects of unvested restricted stock awards with a right to receive non-forfeitable dividends, which are considered participating securities as prescribed by the two-class method under ASC 260.  Diluted EPS is calculated in a similar manner, but the weighted-average number of common shares outstanding during the period is increased to include the weighted-average dilutive effect of "in-the-money" stock options and unvested restricted stock shares using the treasury stock method.
	The standards of accounting for earnings per share require companies to provide a reconciliation of the numerator and denominator of the basic and diluted earnings per share computations.
	Basic and diluted earnings per share were calculated as follows:
		Year Ended September 30,
		2013			2012		2011
	Numerator:
	Net income	$	51,385		$	40,826	$	51,662
	Less: income attributable to participating securities		(494	)		-		-
	Net income available to common shareholders	$	50,891		$	40,826	$	51,662
	Denominator:
	Weighted-average common shares		22,924,056			22,506,408		22,895,568
	(Denominator for basic calculation)
	Weighted-average effect of dilutive securities:
	Share-based compensation		836,010			773,890		539,036
	Diluted weighted-average common shares		23,760,066			23,280,298		23,434,604
	(Denominator for diluted calculation)
	Earnings per share:
	Basic	$	2.22		$	1.81	$	2.26
	Diluted	$	2.14		$	1.75	$	2.2
	For the twelve months ended September 30, 2013, 2012, and 2011, approximately 1.5 million, 1.3 million and 1.3 million shares, respectively, attributable to outstanding stock options were excluded from the calculation of diluted earnings per share because the exercise price of the options was greater than the average market price of our common stock and, therefore, their inclusion would have been anti-dilutive.

FINANCIAL_INFORMATION_BY_INDUS

FINANCIAL INFORMATION BY INDUSTRY SEGMENT, GEOGRAPHIC AREA AND PRODUCT LINE	12 Months Ended
	Sep. 30, 2013
FINANCIAL INFORMATION BY INDUSTRY SEGMENT, GEOGRAPHIC AREA AND PRODUCT LINE [Abstract]	'
FINANCIAL INFORMATION BY INDUSTRY SEGMENT, GEOGRAPHIC AREA AND PRODUCT LINE	'
	18. FINANCIAL INFORMATION BY INDUSTRY SEGMENT, GEOGRAPHIC AREA AND PRODUCT LINE
	We operate predominantly in one industry segment – the development, manufacture, and sale of CMP consumables.  Revenues are attributed to the United States and foreign regions based upon the customer location and not the geographic location from which our products were shipped.
	Financial information by geographic area was as follows:
		Year Ended September 30,
		2013		2012		2011
	Revenue:
	United States	$	53,955	$	56,770	$	61,540
	Asia		347,797		342,958		356,074
	Europe		31,379		27,929		27,828
	Total	$	433,131	$	427,657	$	445,442
	Property, plant and equipment, net:
	United States	$	47,436	$	49,325	$	50,503
	Asia		64,546		75,690		80,280
	Europe		3		5		8
	Total	$	111,985	$	125,020	$	130,791
	The following table shows revenue from sales to customers in foreign countries that accounted for more than ten percent of our total revenue in fiscal 2013, 2012 and 2011:
		Year Ended September 30,
		2013		2012		2011
	Revenue:
	Taiwan	$	133,273	$	124,732	$	132,089
	South Korea		73,778		68,573		56,321
	Japan		*		56,488		57,889
	Singapore		*		*		47,441
	*  Denotes less than ten percent of total
	The following table shows net property, plant and equipment in foreign countries that accounted for more than ten percent of our total net property, plant and equipment in fiscal 2013, 2012 and 2011:
		Year Ended September 30,
		2013		2012		2011
	Property, plant and equipment, net:
	Japan	$	33,566	$	43,411	$	50,236
	Taiwan		17,212		18,397		17,577
	South Korea		12,591		12,580		*
	*  Denotes less than ten percent of total
	The following table shows revenue generated by product line in fiscal 2013, 2012 and 2011:
		Year Ended September 30,
		2013		2012		2011
	Revenue:
	Tungsten slurries	$	155,904	$	161,756	$	164,098
	Dielectric slurries		123,180		119,320		121,543
	Copper slurries		76,367		67,157		76,285
	Polishing pads		32,996		33,725		31,045
	Engineered Surface Finishes		23,999		24,878		24,685
	Data storage slurries		20,685		20,821		27,786
	Total	$	433,131	$	427,657	$	445,442
	In past years, we have referred to "Other Metals slurries" as "Copper slurries", which included slurries for polishing copper, barrier and aluminum.  To more accurately reflect development and changes within this product family, and in particular, growth in revenue for polishing aluminum, we now refer to this product family as "Other Metals slurries".

SELECTED_QUARTERLY_OPERATING_R

SELECTED QUARTERLY OPERATING RESULTS	12 Months Ended
	Sep. 30, 2013
SELECTED QUARTERLY INFORMATION [Abstract]	'
SELECTED QUARTERLY INFORMATION	'
	SELECTED QUARTERLY OPERATING RESULTS
	The following table presents our unaudited financial information for the eight quarterly periods ended September 30, 2013.  This unaudited financial information has been prepared in accordance with accounting principles generally accepted in the United States of America, applied on a basis consistent with the annual audited financial statements and in the opinion of management, include all necessary adjustments, which consist only of normal recurring adjustments necessary to present fairly the financial results for the periods.  The results for any quarter are not necessarily indicative of results for any future period.
	CABOT MICROELECTRONICS CORPORATION
	SELECTED QUARTERLY OPERATING RESULTS
	(Unaudited and in thousands, except per share amounts)
		Sept. 30,			June 30,		March 31,		Dec. 31,		Sept. 30,			June 30,			March 31,		Dec. 31,
		2013			2013		2013		2012		2012			2012			2012		2011
	Revenue	$	116,266		$	109,968	$	100,364	$	106,533	$	110,621		$	115,678		$	99,236	$	102,122
	Cost of goods sold		57,143			55,359		52,019		56,494		56,883			60,462			53,442		52,843
	Gross profit		59,123			54,609		48,345		50,039		53,738			55,216			45,794		49,279
	Operating expenses:
	Research, development and technical		15,835			15,149		15,073		15,316		15,401			15,415			14,071		13,755
	Selling and marketing		7,360			6,470		7,046		7,109		7,288			7,458			7,434		7,336
	General and administrative		12,270			10,776		12,287		10,954		10,572			10,695			15,177		12,901
	Total operating expenses		35,465			32,395		34,406		33,379		33,261			33,568			36,682		33,992
	Operating income		23,658			22,214		13,939		16,660		20,477			21,648			9,112		15,287
	Interest expense		911			907		872		953		961			955			354		39
	Other income (expense), net		(173	)		248		463		854		(681	)		(864	)		97		104
	Income before income taxes		22,574			21,555		13,530		16,561		18,835			19,829			8,855		15,352
	Provision for income taxes		5,805			6,062		4,110		6,858		7,196			6,587			3,325		4,937
	Net income	$	16,769		$	15,493	$	9,420	$	9,703	$	11,639		$	13,242		$	5,530	$	10,415
	Basic earnings per share	$	0.72		$	0.68	$	0.41	$	0.42	$	0.51		$	0.57		$	0.24	$	0.46
	Weighted average basic shares outstanding		23,041			22,951		22,974		22,845		22,920			23,120			22,768		22,508
	Diluted earnings per share	$	0.69		$	0.65	$	0.4	$	0.41	$	0.49		$	0.55		$	0.23	$	0.45
	Weighted average diluted shares outstanding		23,994			23,776		23,871		23,658		23,706			23,939			23,780		22,926
	Dividends per share	$	-		$	-	$	-	$	-	$	-		$	-		$	15	$	-

SCHEDULE_II_VALUATION_AND_QUAL

SCHEDULE II - VALUATION AND QUALIFYING ACCOUNTS	12 Months Ended
	Sep. 30, 2013
SCHEDULE II-VALUATION AND QUALIFYING ACCOUNTS [Abstract]	'
SCHEDULE II - VALUATION AND QUALIFYING ACCOUNTS	'
	SCHEDULE II - VALUATION AND QUALIFYING ACCOUNTS
	As discussed in more detail in Note 2 of the Notes to the Consolidated Financial Statements, in fiscal 2013, in relation to a customer bankruptcy and subsequent approved bankruptcy plan, we charged off an acounts receivable balance against its related allowance for doubtful accounts.  The following table sets forth activities in our allowance for doubtful accounts:
	Allowance For Doubtful Accounts	Balance At Beginning of Year		Amounts Charged To Expenses			Deductions and Adjustments			Balance At End Of Year
	Year ended:
	30-Sep-13	$	4,757	$	173		$	(3,398	)	$	1,532
	30-Sep-12		1,090		3,771			(104	)		4,757
	30-Sep-11		1,121		(18	)		(13	)		1,090
	We maintain a warranty reserve that reflects management's best estimate of the cost to replace product that does not meet our specifications and customers' performance requirements, and costs related to such replacement.  The warranty reserve is based upon a historical product replacement rate, adjusted for any specific known conditions or circumstances.  Additions and deductions to the warranty reserve are recorded in cost of goods sold.  Charges to expenses and deductions, shown below, represent the net change required to maintain an appropriate reserve.
	Warranty Reserves	Balance At Beginning of Year		Reserve For Product Warranty During the Reporting Period			Adjustments To Pre-existing Warranty Reserve			Settlement of Warranty			Balance At End Of Year
	Year ended:
	30-Sep-13	$	359	$	874		$	-		$	(909	)	$	324
	30-Sep-12		384		867			-			(892	)		359
	30-Sep-11		375		1,074			-			(1,065	)		384
	We have provided a valuation allowance on certain deferred tax assets.  The following table sets forth activities in our valuation allowance:
	Valuation Allowance	Balance At Beginning of Year		Amounts Charged To Expenses			Deductions and Adjustments			Balance At End Of Year
	Year ended:
	30-Sep-13	$	1,378	$	910		$	-		$	2,288
	30-Sep-12		-		1,378			-			1,378

SUMMARY_OF_SIGNIFICANT_ACCOUNT1

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Policies)	12 Months Ended
	Sep. 30, 2013
SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES [Abstract]	'
PRINCIPLES OF CONSOLIDATION	'
	PRINCIPLES OF CONSOLIDATION
	The consolidated financial statements include the accounts of Cabot Microelectronics and its subsidiaries.  All intercompany transactions and balances between the companies have been eliminated as of September 30, 2013.
USE OF ESTIMATES	'
	USE OF ESTIMATES
	The preparation of financial statements and related disclosures in conformity with accounting principles generally accepted in the United States of America requires management to make judgments, assumptions and estimates that affect the amounts reported in the consolidated financial statements and accompanying notes.  The accounting estimates that require management's most difficult and subjective judgments include, but are not limited to, those estimates related to bad debt expense, warranty obligations, inventory valuation, valuation and classification of auction rate securities, impairment of long-lived assets and investments, business combinations, goodwill, other intangible assets, share-based compensation, income taxes and contingencies.  We base our estimates on historical experience, current conditions and on various other assumptions that we believe are reasonable under the circumstances.  However, future events are subject to change and estimates and judgments routinely require adjustment.  Actual results may differ from these estimates under different assumptions or conditions.
CASH, CASH EQUIVALENTS AND SHORT-TERM INVESTMENTS	'
	CASH, CASH EQUIVALENTS AND SHORT-TERM INVESTMENTS
	We consider investments in all highly liquid financial instruments with original maturities of three months or less to be cash equivalents.  Short-term investments include securities generally having maturities of 90 days to one year.  We did not own any securities that were considered short-term as of September 30, 2013 or 2012.  See Note 3 for a more detailed discussion of other financial instruments.
ACCOUNTS RECEIVABLE AND ALLOWANCE FOR DOUBTFUL ACCOUNTS	'
	ACCOUNTS RECEIVABLE AND ALLOWANCE FOR DOUBTFUL ACCOUNTS
	Trade accounts receivable are recorded at the invoiced amount and do not bear interest.  We maintain an allowance for doubtful accounts for estimated losses resulting from the potential inability of our customers to make required payments.  Our allowance for doubtful accounts is based on historical collection experience, adjusted for any specific known conditions or circumstances such as customer bankruptcies and increased risk due to economic conditions.  Uncollectible account balances are charged against the allowance when we believe that it is probable that the receivable will not be recovered.
	Accounts receivable, net of allowances for doubtful accounts, was $54,640 as of September 30, 2013 and $53,506 as of September 30, 2012.  In fiscal 2012, we recorded $3,727 in bad debt expense for Elpida Memory, Inc. (Elpida), a significant customer in Japan that filed bankruptcy protection in February 2012.  Elpida has paid the Company on a current basis for all shipments made subsequent to its bankruptcy filing, and pursuant to its bankruptcy plan, will pay us approximately 17% of the balance owed over a period of seven years.    Consequently, we charged off approximately 83% of the Elpida accounts receivable balance against the related allowance for doubtful accounts during the fourth quarter of fiscal 2013.  Amounts charged to expense are recorded in general and administrative expenses.  A portion of our receivables and the related allowance for doubtful accounts is denominated in foreign currencies, so they are subject to forein exchange fluctuations which are included in the table below under the deductions and adjustments.
	Our allowance for doubtful accounts changed during the fiscal year ended September 30, 2013 as follows:		$	4,757
	Balance as of September 30, 2012
	Amounts charged to expense			173
	Deductions and adjustments			(3,398	)
	Balance as of September 30, 2013		$	1,532
CONCENTRATION OF CREDIT RISK	'
	CONCENTRATION OF CREDIT RISK
	Financial instruments that subject us to concentrations of credit risk consist principally of accounts receivable.  We perform ongoing credit evaluations of our customers' financial conditions and generally do not require collateral to secure accounts receivable.  Our exposure to credit risk associated with nonpayment is affected principally by conditions or occurrences within the semiconductor industry and global economy.  Prior to the Elpida bankruptcy in fiscal 2012, we had not experienced significant losses relating to accounts receivable from individual customers or groups of customers.
	Customers who represented more than 10% of revenue are as follows:
			Year Ended September 30,
			2013			2012			2011
	Taiwan Semiconductor Manufacturing Co. (TSMC)			21	%		18	%		17	%
	Samsung			13	%		13	%		10	%
	TSMC accounted for 16.7% and 17.1% of net accounts receivable at September 30, 2013 and 2012, respectively.  Samsung accounted for 11.8% and 12.1% of net accounts receivable at September 30, 2013 and 2012, respectively.
FAIR VALUES OF FINANCIAL INSTRUMENTS	'
	FAIR VALUES OF FINANCIAL INSTRUMENTS
	The recorded amounts of cash, accounts receivable, and accounts payable approximate their fair values due to their short-term, highly liquid characteristics.  The fair value of our long-term auction rate securities (ARS) is determined through discounted cash flow analyses.  See Note 3 for a more detailed discussion of the fair value of financial instruments.
INVENTORIES	'
	INVENTORIES
	Inventories are stated at the lower of cost, determined on the first-in, first-out (FIFO) basis, or market.  Finished goods and work in process inventories include material, labor and manufacturing overhead costs.  We regularly review and write down the value of inventory as required for estimated obsolescence or lack of marketability.  An inventory reserve is maintained based upon a historical percentage of actual inventories written off and applied against inventory value at the end of the period, adjusted for known conditions and circumstances.
PROPERTY, PLANT AND EQUIPMENT	'
	PROPERTY, PLANT AND EQUIPMENT
	Property, plant and equipment are recorded at cost.  Depreciation is based on the following estimated useful lives of the assets using the straight-line method:
	Buildings	15-25 years
	Machinery and equipment	3-10 years
	Furniture and fixtures	5-10 years
	Information systems	3-5 years
	Assets under capital leases	Lesser of term of lease or estimated useful life
	Expenditures for repairs and maintenance are charged to expense as incurred.  Expenditures for major renewals and betterments are capitalized and depreciated over the remaining useful lives.  As assets are retired or sold, the related cost and accumulated depreciation are removed from the accounts and any resulting gain or loss is included in the results of operations.  We capitalize the costs related to the design and development of software used for internal purposes; however, these costs are not material.
IMPAIRMENT OF LONG-LIVED ASSETS	'
	IMPAIRMENT OF LONG-LIVED ASSETS
	Reviews are regularly performed to determine whether facts and circumstances exist that indicate the carrying amount of assets may not be recoverable or the useful life is shorter than originally estimated.  Asset recoverability assessment begins by comparing the projected undiscounted cash flows associated with the related asset or group of assets over their remaining lives against their respective carrying amounts.  Impairment, if any, is based on the excess of the carrying amount over the fair value of those assets.  If assets are determined to be recoverable, but their useful lives are shorter than originally estimated, the net book value of the asset is depreciated over the newly determined remaining useful life.
GOODWILL AND INTANGIBLE ASSETS	'
	GOODWILL AND INTANGIBLE ASSETS
	We amortize intangible assets with finite lives over their estimated useful lives, which range from one to ten and one half  years.  Intangible assets with finite lives are reviewed for impairment using a process similar to that used to evaluate other long-lived assets.  Goodwill and indefinite lived intangible assets are not amortized and are tested annually in the fourth fiscal quarter or more frequently if indicators of potential impairment exist, using a fair-value-based approach.  The recoverability of goodwill is measured at the reporting unit level, which is defined as either an operating segment or one level below an operating segment, referred to as a component.  A component is a reporting unit when the component constitutes a business for which discreet financial information is available and segment management regularly reviews the operating results of the component.  Components may be combined into one reporting unit when they have similar economic characteristics.  We had three reporting units to which we allocated goodwill and intangible assets as of September 30, 2013.  Goodwill impairment testing requires a comparison of the fair value of each reporting unit to the carrying value.  If the carrying value exceeds fair value, goodwill is considered impaired.  The amount of the impairment is the difference between the carrying value of goodwill and the "implied" fair value.  The fair value of the reporting unit may be determined using a discounted cash flow analysis of our projected future results.  An entity has the option to assess qualitative factors to determine if the two-step impairment test must be performed.  We elected to perform a discounted cash flow analysis in fiscal 2013 when we performed our annual impairment review of goodwill.  An entity also has the option to assess qualitative factors in its impairment review of indefinite-lived intangible assets.  However, we elected to use the royalty savings method in fiscal 2013 when we performed our impairment review of our indefinite-lived intangible assets.  We determined that goodwill and other intangible assets were not impaired as of September 30, 2013.
WARRANTY RESERVE	'
	WARRANTY RESERVE
	We maintain a warranty reserve that reflects management's best estimate of the cost to replace product that does not meet our specifications and customers' performance requirements.  The warranty reserve is based upon a historical product return rate, adjusted for any specific known conditions or circumstances.  Adjustments to the warranty reserve are recorded in cost of goods sold.
FOREIGN CURRENCY TRANSLATION	'
	FOREIGN CURRENCY TRANSLATION
	Certain operating activities in Asia and Europe are denominated in local currency, considered to be the functional currency.  Assets and liabilities of these operations are translated using exchange rates in effect at the end of the year, and revenue and costs are translated using weighted-average exchange rates for the year.  The related translation adjustments are reported in comprehensive income in stockholders' equity.
FOREIGN EXCHANGE MANAGEMENT	'
	FOREIGN EXCHANGE MANAGEMENT
	We transact business in various foreign currencies, primarily the Japanese yen, the New Taiwan dollar and Korean won.  Our exposure to foreign currency exchange risks has not been significant because a large portion of our business is denominated in U.S. dollars.  However, there was a significant weakening of the Japanese yen against the U.S. dollar during fiscal 2013, which had some positive impact on our results of operations.  Periodically we enter into forward foreign exchange contracts in an effort to mitigate the risks associated with currency fluctuations on certain foreign currency balance sheet exposures.  Our foreign exchange contracts do not qualify for hedge accounting under the accounting rules for derivative instruments.  See Note 10 for a more detailed discussion of derivative financial instruments.
INTERCOMPANY LOAN ACCOUNTING	'
	INTERCOMPANY LOAN ACCOUNTING
	We maintain intercompany loan agreements with our wholly-owned subsidiary, Nihon Cabot Microelectronics K.K. ("the K.K."), under which we provided funds to the K.K. to finance the purchase of certain assets from our former Japanese branch at the time of the establishment of this subsidiary, for the purchase of land adjacent to our Geino, Japan, facility, for the construction of our Asia Pacific technology center, and for the purchase of a 300 millimeter polishing tool and related metrology equipment, all of which are part of the K.K., as well as for general business purposes.  Since settlement of the notes is expected in the foreseeable future, and our subsidiary has been consistently making timely payments on the loans, the loans are considered foreign-currency transactions.  Therefore the associated foreign exchange gains and losses are recognized as other income or expense rather than being deferred in the cumulative translation account in other comprehensive income.
	We also maintain intercompany loan agreements between some of our wholly-owned foreign subsidiaries, including from Cabot Microelectronics Singapore Pte. Ltd. and Epoch Material Co., Ltd. in Taiwan to Hanguk Cabot Microelectronics, LLC in South Korea.  These loans have provided funds for the construction and operation of our research, development and manufacturing facility in South Korea.  These loans are also considered foreign currency transactions and are accounted for in the same manner as our intercompany loans to the K.K.
PURCHASE COMMITMENTS	'
	PURCHASE COMMITMENTS
	We have entered into unconditional purchase obligations, which include noncancelable purchase commitments and take-or-pay arrangements with suppliers.  We review our agreements and make an assessment of the likelihood of a shortfall in purchases and determine if it is necessary to record a liability.
REVENUE RECOGNITION	'
	REVENUE RECOGNITION
	Revenue from CMP consumable products is recognized when title is transferred to the customer, assuming all revenue recognition criteria are met.  Title transfer generally occurs upon shipment to the customer or when inventory held on consignment is consumed by the customer, subject to the terms and conditions of the particular customer arrangement.  We have consignment agreements with a number of our customers that require, at a minimum, monthly consumption reports that enable us to record revenue and inventory usage in the appropriate period.
	We market our products through distributors in a few areas of the world.  We recognize revenue upon shipment and when title is transferred to the distributor.  We do not have any arrangements with distributors that include payment terms, rights of return, or rights of exchange outside the normal course of business, or any other significant matters that we believe would impact the timing of revenue recognition.
	Within our Engineered Surface Finishes (ESF) business, sales of equipment are recorded as revenue upon delivery and customer acceptance.  Amounts allocated to installation and training are deferred until those services are provided and are not material.
	Revenues are reported net of any value-added tax or other such tax assessed by a governmental authority on our revenue-producing activities.
SHIPPING AND HANDLING	'
	SHIPPING AND HANDLING
	Costs related to shipping and handling are included in cost of goods sold.
RESEARCH, DEVELOPMENT AND TECHNICAL	'
	RESEARCH, DEVELOPMENT AND TECHNICAL
	Research, development and technical costs are expensed as incurred and consist primarily of staffing costs, materials and supplies, depreciation, utilities and other facilities costs.
INCOME TAXES	'
	INCOME TAXES
	Current income taxes are determined based on estimated taxes payable or refundable on tax returns for the current year.  Deferred income taxes are determined using enacted tax rates for the effect of temporary differences between the book and tax bases of recorded assets and liabilities.  The effect on deferred tax assets and liabilities of a change in tax rates is recognized in income in the period that includes the enactment date.  Provisions are made for both U.S. and any foreign deferred income tax liability or benefit.  We recognize the tax benefit of an uncertain tax position only if it is more likely than not that the tax position will be sustained by the taxing authorities, based on the technical merits of the position.  In fiscal 2012 and 2011, we elected to permanently reinvest the earnings of certain of our foreign subsidiaries outside the U.S. rather than repatriating the earnings to the U.S.  In fiscal 2013, we elected to permanently reinvest the earnings of all of our foreign subsidiaries.  See Note 15 for additional information on income taxes.
SHARE-BASED COMPENSATION	'
	SHARE-BASED COMPENSATION
	We record share-based compensation expense for all share-based awards, including stock option grants, restricted stock and restricted stock unit awards and employee stock purchases.  We calculate share-based compensation expense using the straight-line approach based on awards ultimately expected to vest, which requires the use of an estimated forfeiture rate.  Our estimated forfeiture rate is primarily based on historical experience, but may be revised in future periods if actual forfeitures differ from the estimate.  We use the Black-Scholes option-pricing model to estimate the grant date fair value of our stock options and employee stock purchase plan purchases.  This model requires the input of highly subjective assumptions, including the price volatility of the underlying stock, the expected term of our stock options and the risk-free interest rate.  We estimate the expected volatility of our stock options based on a combination of our stock's historical volatility and the implied volatilities from actively-traded options on our stock.  We calculate the expected term of our stock options using historical stock option exercise data, and we add a slight premium to this expected term for employees who meet the definition of retirement eligible pursuant to their grants during the contractual term of the grant.  The risk-free rate is derived from the U.S. Treasury yield curve in effect at the time of grant.
	The fair value of our restricted stock and restricted stock unit awards represents the closing price of our common stock on the date of award.
	For additional information regarding our share-based compensation plans, refer to Note 11.
EARNINGS PER SHARE	'
	EARNINGS PER SHARE
	Basic earnings per share (EPS) is calculated by dividing net income available to common stockholders by the weighted-average number of common shares outstanding during the period, excluding the effects of unvested restricted stock awards with a right to receive non-forfeitable dividends, which are considered participating securities as prescribed by the two class method under ASC Topic 260, Earnings Per Share (ASC 260).  Diluted EPS is calculated in a similar manner, but the weighted-average number of common shares outstanding during the period is increased to include the weighted-average dilutive effect of "in-the-money" stock options and unvested restricted stock shares using the treasury stock method.
COMPREHENSIVE INCOME	'
	COMPREHENSIVE INCOME
	Comprehensive income primarily differs from net income due to foreign currency translation adjustments.

SUMMARY_OF_SIGNIFICANT_ACCOUNT2

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Tables)	12 Months Ended
	Sep. 30, 2013
SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES [Abstract]	'
Schedule of Allowance for Doubtful Accounts	'
	Our allowance for doubtful accounts changed during the fiscal year ended September 30, 2013 as follows:		$	4,757
	Balance as of September 30, 2012
	Amounts charged to expense			173
	Deductions and adjustments			(3,398	)
	Balance as of September 30, 2013		$	1,532
Schedule of customers representing more than ten percent of total revenue	'
	Customers who represented more than 10% of revenue are as follows:
			Year Ended September 30,
			2013			2012			2011
	Taiwan Semiconductor Manufacturing Co. (TSMC)			21	%		18	%		17	%
	Samsung			13	%		13	%		10	%
Schedule of property, plant and equipment useful lives	'
	Property, plant and equipment are recorded at cost.  Depreciation is based on the following estimated useful lives of the assets using the straight-line method:
	Buildings	15-25 years
	Machinery and equipment	3-10 years
	Furniture and fixtures	5-10 years
	Information systems	3-5 years
	Assets under capital leases	Lesser of term of lease or estimated useful life

FAIR_VALUE_OF_FINANCIAL_INSTRU1

FAIR VALUE OF FINANCIAL INSTRUMENTS (Tables)	12 Months Ended
	Sep. 30, 2013
FAIR VALUE OF FINANCIAL INSTRUMENTS [Abstract]	'
Schedule of Fair Value of Financial Instruments	'
	The following tables present financial instruments, other than long-term debt, that we measured at fair value on a recurring basis at September 30, 2013 and 2012.  See Note 9 for a detailed discussion of our long-term debt.  We have chosen to not measure any of our other financial instruments at fair value as we believe their carrying value approximates their fair value.  We have classified the following assets in accordance with the fair value hierarchy set forth in the applicable standards.  In instances where the inputs used to measure the fair value of an asset fall into more than one level of the hierarchy, we have classified them based on the lowest level input that is significant to the determination of the fair value.
		Level 1			Level 2		Level 3		Total
	30-Sep-13								Fair Value
	Cash and cash equivalents	$	226,029		$	-	$	-	$	226,029
	Auction rate securities (ARS)		-			-		7,966		7,966
	Other long-term investments		1,375			-		-		1,375
	Total	$	227,404		$	-	$	7,966	$	235,370
		Level 1			Level 2		Level 3		Total
	30-Sep-12								Fair Value
	Cash and cash equivalents	$	178,459		$	-	$	-	$	178,459
	Auction rate securities (ARS)		-			-		7,991		7,991
	Other long-term investments		1,082			-		-		1,082
	Total	$	179,541		$	-	$	7,991	$	187,532
Schedule of Auction Rate Securities (ARS) Activity	'
	The following table presents a reconciliation of the activity in fiscal 2013 for fair value measurements using level 3 inputs:
	Balance as of September 30, 2012	$	7,991
	Sales of ARS		(25	)
	Balance as of September 30, 2013	$	7,966

INVENTORIES_Tables

INVENTORIES (Tables)	12 Months Ended
	Sep. 30, 2013
INVENTORIES [Abstract]	'
Schedule of inventories	'
	Inventories consisted of the following:
		September 30,
		2013		2012
	Raw materials	$	38,004	$	34,591
	Work in process		5,001		6,333
	Finished goods		20,781		25,548
	Total	$	63,786	$	66,472

PROPERTY_PLANT_AND_EQUIPMENT_T

PROPERTY, PLANT AND EQUIPMENT (Tables)	12 Months Ended
	Sep. 30, 2013
PROPERTY, PLANT AND EQUIPMENT [Abstract]	'
Schedule of Property, plant and equipment	'
	Property, plant and equipment consisted of the following:
		September 30,
		2013			2012
	Land	$	18,914		$	21,566
	Buildings		97,542			101,627
	Machinery and equipment		175,406			181,117
	Furniture and fixtures		6,234			6,417
	Information systems		26,208			25,346
	Capital leases		-			66
	Construction in progress		5,072			4,890
	Total property, plant and equipment		329,376			341,029
	Less: accumulated depreciation and amortization of assets under capital leases		(217,391	)		(216,009	)
	Net property, plant and equipment	$	111,985		$	125,020

GOODWILL_AND_OTHER_INTANGIBLE_1

GOODWILL AND OTHER INTANGIBLE ASSETS (Tables)	12 Months Ended
	Sep. 30, 2013
GOODWILL AND OTHER INTANGIBLE ASSETS [Abstract]	'
Components of other intangible assets	'
	The components of other intangible assets are as follows:
		30-Sep-13				30-Sep-12
		Gross Carrying		Accumulated		Gross Carrying		Accumulated
		Amount		Amortization		Amount		Amortization
	Other intangible assets subject to amortization:
	Product technology	$	8,362	$	5,853	$	8,387	$	4,902
	Acquired patents and licenses		8,270		7,196		8,270		6,775
	Trade secrets and know-how		2,550		2,550		2,550		2,550
	Customer relationships, distribution rights and other		12,496		7,484		12,586		6,283
	Total other intangible assets subject to amortization		31,678		23,083		31,793		20,510
	Total other intangible assets not subject to amortization*		1,190				1,190
	Total other intangible assets	$	32,868	$	23,083	$	32,983	$	20,510
	* Total other intangible assets not subject to amortization primarily consist of trade names.
Estimated future amortization expense for the succeeding five fiscal years	'
	Amortization expense was $2,622, $2,682 and $2,720 for fiscal 2013, 2012 and 2011, respectively.  Estimated future amortization expense for the five succeeding fiscal years is as follows:
		Estimated Amortization
		Expense
	Fiscal Year
	2014	$	2,497
	2015		2,429
	2016		2,009
	2017		1,177
	2018		466

OTHER_LONGTERM_ASSETS_Tables

OTHER LONG-TERM ASSETS (Tables)	12 Months Ended
	Sep. 30, 2013
OTHER LONG-TERM ASSETS [Abstract]	'
Schedule of other long term assets	'
	Other long-term assets consisted of the following:
		September 30,
		2013		2012
	Auction rate securities	$	7,966	$	7,991
	Other long-term assets		3,086		2,872
	Other long-term investments		1,375		1,082
	Total	$	12,427	$	11,945

ACCRUED_EXPENSES_INCOME_TAXES_1

ACCRUED EXPENSES, INCOME TAXES PAYABLE AND OTHER CURRENT LIABILITIES (Tables)	12 Months Ended
	Sep. 30, 2013
ACCRUED EXPENSES, INCOME TAXES PAYABLE AND OTHER CURRENT LIABILITIES [Abstract]	'
Schedule of accrued expenses, income taxes payable and other current liabilities	'
	Accrued expenses, income taxes payable and other current liabilities consisted of the following:
		September 30,
		2013		2012
	Accrued compensation	$	24,601	$	18,532
	Goods and services received, not yet invoiced		4,681		3,478
	Deferred revenue and customer advances		458		3,341
	Warranty accrual		324		359
	Income taxes payable		6,931		2,843
	Taxes, other than income taxes		951		1,041
	Other		1,953		3,144
	Total	$	39,899	$	32,738

DEBT_Tables

DEBT (Tables)	12 Months Ended
	Sep. 30, 2013
DEBT [Abstract]	'
Schedule of Maturities of Long-term Debt	'
	As of September 30, 2013, scheduled principal repayments of the Term Loan were as follows:
		Principal Repayments
	Fiscal Year
	2014	$	10,938
	2015		15,312
	2016		21,875
	2017		113,750
	Total	$	161,875

DERIVATIVE_FINANCIAL_INSTRUMEN1

DERIVATIVE FINANCIAL INSTRUMENTS (Tables)	12 Months Ended
	Sep. 30, 2013
DERIVATIVE FINANCIAL INSTRUMENTS [Abstract]	'
Schedule of Fair Value of Derivative Instruments in the Consolidated Balance Sheet	'
	The fair value of our derivative instrument included in the Consolidated Balance Sheet, which was determined using Level 2 inputs, was as follows:
			Asset Derivatives				Liability Derivatives
	Derivatives not designated as hedging instruments		Fair Value at September 30, 2013		Fair Value at September 30, 2012		Fair Value at September 30, 2013			Fair Value at September 30, 2012
		Balance Sheet Location
	Foreign exchange contracts	Prepaid expenses and other current assets	$	60	$	38	$	-		$	-
		Accrued expenses and other current liabilities	$	-	$	-	$	-		$	-
Schedule of the Effect of Derivative Instruments on the Consolidated Statement of Income	'
	The following table summarizes the effect of our derivative instrument on our Consolidated Statement of Income for the fiscal years ended September 30, 2013, 2012 and 2011:
			Gain (Loss) Recognized in Statement of Income
			Fiscal Year Ended
	Derivatives not designated as hedging instruments	Statement of Income Location	30-Sep-13		30-Sep-12		30-Sep-11
	Foreign exchange contracts	Other income (expense), net	$	252	$	154	$	(806	)

SHAREBASED_COMPENSATION_PLANS_

SHARE-BASED COMPENSATION PLANS (Tables)	12 Months Ended
	Sep. 30, 2013
SHARE-BASED COMPENSATION PLANS [Abstract]	'
Schedule of fair value assumptions and methodology	'
	The fair value of our share-based awards, as shown below, was estimated using the Black-Scholes model with the following weighted-average assumptions, excluding the effect of our leveraged recapitalization:
		Year Ended September 30,
		2013			2012			2011
	Stock Options
	Weighted-average grant date fair value	$	12.13		$	15.66		$	16.49
	Expected term (in years)		6.37			6.38			6.28
	Expected volatility		36	%		38	%		36	%
	Risk-free rate of return		0.9	%		1.3	%		2.1	%
	Dividend yield		-			-			-
	ESPP
	Weighted-average grant date fair value	$	7.41		$	8.78		$	9.05
	Expected term (in years)		0.5			0.5			0.5
	Expected volatility		25	%		36	%		28	%
	Risk-free rate of return		0.1	%		0.1	%		0.2	%
	Dividend yield		-			-			-
Share based compensation expense	'
	Total share-based compensation expense for the years ended September 30, 2013, 2012 and 2011, is as follows:
		Year Ended September 30, 2013,
	Income statement classifications:	2013			2012			2011
	Cost of goods sold	$	1,707		$	1,541		$	1,221
	Research, development and technical		1,301			1,105			1,060
	Selling and marketing		1,367			1,392			1,124
	General and administrative		8,975			9,268			9,241
	Tax benefit		(4,581	)		(4,118	)		(4,060	)
	Total share-based compensation expense, net of tax	$	8,769		$	9,188		$	8,586
Summary of stock option activity	'
	A summary of stock option activity under the EIP and OIP as of September 30, 2013, and changes during the fiscal 2013 are presented below:
								Weighted
								Average
					Weighted			Remaining			Aggregate
					Average			Contractual			Intrinsic
		Stock			Exercise			Term			Value
		Options			Price			(in years)			(in thousands)
	Outstanding at September 30, 2012		5,133,626		$	26.75
	Granted		533,424			32.89
	Exercised		(1,071,750	)		26.61
	Forfeited or canceled		(321,413	)		34.72
	Outstanding at September 30, 2013		4,273,887		$	26.95			5.2		$	49,410
	Exercisable at September 30, 2013		2,881,901		$	25.82			3.7		$	36,568
	Expected to vest after September 30, 2013		1,321,760		$	29.53			8.2		$	11,870
Summary of restricted stock awards and restricted stock unit awards	'
	A summary of the status of the restricted stock awards and restricted stock unit awards outstanding that were granted under the EIP and OIP as of September 30, 2013, and changes during fiscal 2013, are presented below:
		Restricted			Weighted
		Stock			Average
		Awards and			Grant Date
		Units			Fair Value
	Nonvested at September 30, 2012		394,124		$	34.15
	Granted		184,581			32.94
	Vested		(174,362	)		31.3
	Forfeited		(7,914	)		34.23
	Nonvested at September 30, 2013		396,429		$	34.84

OTHER_INCOME_EXPENSE_NET_Table

OTHER INCOME (EXPENSE), NET (Tables)	12 Months Ended
	Sep. 30, 2013
OTHER INCOME (EXPENSE), NET [Abstract]	'
Other income (expense), net	'
	Other income (expense), net, consisted of the following:
		Year Ended September 30,
		2013		2012			2011
	Interest income	$	145	$	146		$	238
	Other income (expense)		1,247		(1,490	)		(1,556	)
	Total other income (expense), net	$	1,392	$	(1,344	)	$	(1,318	)

STOCKHOLDERS_EQUITY_Tables

STOCKHOLDERS EQUITY (Tables)	12 Months Ended
	Sep. 30, 2013
STOCKHOLDERS EQUITY [Abstract]	'
Summary of capital stock activity	'
	The following is a summary of our capital stock activity over the past three years:
		Number of Shares
		Common	Treasury
		Stock	Stock
	30-Sep-10	26,384,715	3,446,069
	Exercise of stock options	1,085,965
	Restricted stock under EIP, net of forfeitures	115,069
	Restricted stock under Deposit Share Plan	5,223
	Common stock under ESPP	61,364
	Repurchases of common stock under share repurchase plans		1,235,668
	Repurchases of common stock – other		33,840
	30-Sep-11	27,652,336	4,715,577
	Exercise of stock options	976,645
	Restricted stock under EIP, net of forfeitures	159,879
	Restricted stock under Deposit Share Plan, net of forfeitures	5,022
	Common stock under ESPP	70,645
	Repurchases of common stock under share repurchase plans		929,407
	Repurchases of common stock – other		37,304
	30-Sep-12	28,864,527	5,682,288
	Exercise of stock options	1,071,750
	Restricted stock under EIP and OIP, net of forfeitures	185,925
	Restricted stock under Deposit Share Plan, net of forfeitures	6,773
	Common stock under ESPP	84,602
	Repurchases of common stock under share repurchase plans		1,144,836
	Repurchases of common stock – other		39,551
	30-Sep-13	30,213,577	6,866,675

INCOME_TAXES_Tables

INCOME TAXES (Tables)	12 Months Ended
	Sep. 30, 2013
INCOME TAXES [Abstract]	'
Schedule of income before income taxes	'
	Income before income taxes was as follows:
		Year Ended September 30,
		2013			2012			2011
	Domestic	$	40,045		$	55,555		$	54,886
	Foreign		34,175			7,316			24,026
	Total	$	74,220		$	62,871		$	78,912
Schedule of taxes on income by jurisdiction	'
	Taxes on income consisted of the following:
		Year Ended September 30,
		2013			2012			2011
	U.S. federal and state:
	Current	$	17,649		$	19,975		$	15,700
	Deferred		(3,576	)		(308	)		6,194
	Total	$	14,073		$	19,667		$	21,894
	Foreign:
	Current	$	8,304		$	5,593		$	6,616
	Deferred		458			(3,215	)		(1,260	)
	Total		8,762			2,378			5,356
	Total U.S. and foreign	$	22,835		$	22,045		$	27,250
Income tax rate reconciliation	'
	The provision for income taxes at our effective tax rate differed from the statutory rate as follows:
		Year Ended September 30,
		2013			2012			2011
	Federal statutory rate		35	%		35	%		35	%
	U.S. benefits from research and experimentation activities		-2	%		-0.5	%		-2	%
	State taxes, net of federal effect		0.3	%		0.2	%		0.6	%
	Foreign income at other than U.S. rates		-3.1	%		-1.9	%		-2.8	%
	Change in valuation allowance		1.4	%		1.1	%		0	%
	Executive compensation		0.2	%		0.8	%		1.4	%
	Share-based compensation		0.1	%		0.7	%		3.3	%
	Adjustment of prior amounts		-0.2	%		-0.2	%		0	%
	Domestic production deduction		-0.2	%		-0.5	%		-0.8	%
	Tax-exempt interest income		0	%		0	%		-0.1	%
	Other, net		-0.7	%		0.4	%		-0.1	%
	Provision for income taxes		30.8	%		35.1	%		34.5	%
Reconciliation of gross unrecognized tax benefits	'
	The following table presents the changes in the balance of gross unrecognized tax benefits during the last three fiscal years:
	Balance September 30, 2010	$	173
	Additions for tax positions relating to the current fiscal year		123
	Additions for tax positions relating to prior fiscal years		307
	Settlements with taxing authorities		-
	Lapse of statute of limitations		-
	Balance September 30, 2011		603
	Additions for tax positions relating to the current fiscal year		51
	Additions for tax positions relating to prior fiscal years		114
	Settlements with taxing authorities		(353	)
	Lapse of statute of limitations		(132	)
	Balance September 30, 2012		283
	Additions for tax positions relating to the current fiscal year		228
	Additions for tax positions relating to prior fiscal years		247
	Settlements with taxing authorities		-
	Lapse of statute of limitations		-
	Balance September 30, 2013	$	758
Schedule of significant components of deferred income tax	'
	Significant components of net deferred tax assets and liabilities were as follows:
		September 30,
		2013			2012
	Deferred tax assets:
	Employee benefits	$	3,892		$	4,035
	Inventory		3,138			2,930
	Bad debt reserve		515			1,708
	Share-based compensation expense		13,907			12,659
	Net operating losses		759			2,292
	Other		2,723			2,656
	Valuation allowance		(2,288	)		(1,378	)
	Total deferred tax assets	$	22,646		$	24,902
	Deferred tax liabilities:
	Translation adjustment	$	3,247		$	7,966
	Depreciation and amortization		2,046			3,776
	Unremitted foreign earnings		-			1,810
	Other		962			645
	Total deferred tax liabilities	$	6,255		$	14,197

COMMITMENTS_AND_CONTINGENCIES_

COMMITMENTS AND CONTINGENCIES (Tables)	12 Months Ended
	Sep. 30, 2013
COMMITMENTS AND CONTINGENCIES [Abstract]	'
Schedule of product warranty reserve activity	'
	Our warranty reserve requirements changed during fiscal 2013 as follows:
	Balance as of September 30, 2012	$	359
	Reserve for product warranty during the reporting period		874
	Settlement of warranty		(909	)
	Balance as of September 30, 2013	$	324
Future minimum rental commitments under noncancelable leases	'
	Future minimum rental commitments under noncancelable leases as of September 30, 2013 are as follows:
	Fiscal Year	Operating
	2014	$	2,907
	2015		1,775
	2016		1,583
	2017		1,195
	2018		157
	Thereafter		450
		$	8,067

EARNINGS_PER_SHARE_Tables

EARNINGS PER SHARE (Tables)	12 Months Ended
	Sep. 30, 2013
EARNINGS PER SHARE [Abstract]	'
Earnings Per Share	'
	Basic and diluted earnings per share were calculated as follows:
		Year Ended September 30,
		2013			2012		2011
	Numerator:
	Net income	$	51,385		$	40,826	$	51,662
	Less: income attributable to participating securities		(494	)		-		-
	Net income available to common shareholders	$	50,891		$	40,826	$	51,662
	Denominator:
	Weighted-average common shares		22,924,056			22,506,408		22,895,568
	(Denominator for basic calculation)
	Weighted-average effect of dilutive securities:
	Share-based compensation		836,010			773,890		539,036
	Diluted weighted-average common shares		23,760,066			23,280,298		23,434,604
	(Denominator for diluted calculation)
	Earnings per share:
	Basic	$	2.22		$	1.81	$	2.26
	Diluted	$	2.14		$	1.75	$	2.2

FINANCIAL_INFORMATION_BY_INDUS1

FINANCIAL INFORMATION BY INDUSTRY SEGMENT, GEOGRAPHIC AREA AND PRODUCT LINE (Tables)	12 Months Ended
	Sep. 30, 2013
FINANCIAL INFORMATION BY INDUSTRY SEGMENT, GEOGRAPHIC AREA AND PRODUCT LINE [Abstract]	'
Revenue and net property, plant and equipment by customer location	'
	Financial information by geographic area was as follows:
		Year Ended September 30,
		2013		2012		2011
	Revenue:
	United States	$	53,955	$	56,770	$	61,540
	Asia		347,797		342,958		356,074
	Europe		31,379		27,929		27,828
	Total	$	433,131	$	427,657	$	445,442
	Property, plant and equipment, net:
	United States	$	47,436	$	49,325	$	50,503
	Asia		64,546		75,690		80,280
	Europe		3		5		8
	Total	$	111,985	$	125,020	$	130,791
Revenue by country greater than ten percent of total revenue	'
	The following table shows revenue from sales to customers in foreign countries that accounted for more than ten percent of our total revenue in fiscal 2013, 2012 and 2011:
		Year Ended September 30,
		2013		2012		2011
	Revenue:
	Taiwan	$	133,273	$	124,732	$	132,089
	South Korea		73,778		68,573		56,321
	Japan		*		56,488		57,889
	Singapore		*		*		47,441
	*  Denotes less than ten percent of total
Net property, plant and equipment in foreign countries greater than ten percent of total net property, plant and equipment	'
	The following table shows net property, plant and equipment in foreign countries that accounted for more than ten percent of our total net property, plant and equipment in fiscal 2013, 2012 and 2011:
		Year Ended September 30,
		2013		2012		2011
	Property, plant and equipment, net:
	Japan	$	33,566	$	43,411	$	50,236
	Taiwan		17,212		18,397		17,577
	South Korea		12,591		12,580		*
	*  Denotes less than ten percent of total
Schedule of revenue by product line	'
	The following table shows revenue generated by product line in fiscal 2013, 2012 and 2011:
		Year Ended September 30,
		2013		2012		2011
	Revenue:
	Tungsten slurries	$	155,904	$	161,756	$	164,098
	Dielectric slurries		123,180		119,320		121,543
	Copper slurries		76,367		67,157		76,285
	Polishing pads		32,996		33,725		31,045
	Engineered Surface Finishes		23,999		24,878		24,685
	Data storage slurries		20,685		20,821		27,786
	Total	$	433,131	$	427,657	$	445,442

SELECTED_QUARTERLY_INFORMATION

SELECTED QUARTERLY INFORMATION (Tables)	12 Months Ended
	Sep. 30, 2013
SELECTED QUARTERLY INFORMATION [Abstract]	'
Selected Quarterly Operating Results	'
	CABOT MICROELECTRONICS CORPORATION
	SELECTED QUARTERLY OPERATING RESULTS
	(Unaudited and in thousands, except per share amounts)
		Sept. 30,			June 30,		March 31,		Dec. 31,		Sept. 30,			June 30,			March 31,		Dec. 31,
		2013			2013		2013		2012		2012			2012			2012		2011
	Revenue	$	116,266		$	109,968	$	100,364	$	106,533	$	110,621		$	115,678		$	99,236	$	102,122
	Cost of goods sold		57,143			55,359		52,019		56,494		56,883			60,462			53,442		52,843
	Gross profit		59,123			54,609		48,345		50,039		53,738			55,216			45,794		49,279
	Operating expenses:
	Research, development and technical		15,835			15,149		15,073		15,316		15,401			15,415			14,071		13,755
	Selling and marketing		7,360			6,470		7,046		7,109		7,288			7,458			7,434		7,336
	General and administrative		12,270			10,776		12,287		10,954		10,572			10,695			15,177		12,901
	Total operating expenses		35,465			32,395		34,406		33,379		33,261			33,568			36,682		33,992
	Operating income		23,658			22,214		13,939		16,660		20,477			21,648			9,112		15,287
	Interest expense		911			907		872		953		961			955			354		39
	Other income (expense), net		(173	)		248		463		854		(681	)		(864	)		97		104
	Income before income taxes		22,574			21,555		13,530		16,561		18,835			19,829			8,855		15,352
	Provision for income taxes		5,805			6,062		4,110		6,858		7,196			6,587			3,325		4,937
	Net income	$	16,769		$	15,493	$	9,420	$	9,703	$	11,639		$	13,242		$	5,530	$	10,415
	Basic earnings per share	$	0.72		$	0.68	$	0.41	$	0.42	$	0.51		$	0.57		$	0.24	$	0.46
	Weighted average basic shares outstanding		23,041			22,951		22,974		22,845		22,920			23,120			22,768		22,508
	Diluted earnings per share	$	0.69		$	0.65	$	0.4	$	0.41	$	0.49		$	0.55		$	0.23	$	0.45
	Weighted average diluted shares outstanding		23,994			23,776		23,871		23,658		23,706			23,939			23,780		22,926
	Dividends per share	$	-		$	-	$	-	$	-	$	-		$	-		$	15	$	-

BACKGROUND_AND_BASIS_OF_PRESEN1

BACKGROUND AND BASIS OF PRESENTATION (Details) (USD $)	3 Months Ended								12 Months Ended
In Thousands, except Per Share data, unless otherwise specified	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2011	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2011
Net income	$16,769	$15,493	$9,420	$9,703	$11,639	$13,242	$5,530	$10,415	$51,385	$40,826	$51,662
Diluted earnings per share (in dollars per share)	$0.69	$0.65	$0.40	$0.41	$0.49	$0.55	$0.23	$0.45	$2.14	$1.75	$2.20
Income tax recorded to correct tax accounting related to Epoch acquisition	'	'	'	'	'	'	'	'	'	172	'
Increase cumulative translation adjustment related to acquisition of Epoch	'	'	'	'	'	2,172	'	'	'	'	'
Increase goodwill related to the acquisition of Epoch	'	'	'	'	'	1,712	'	'	'	'	'
Decrease in deferred tax liabilities related to the acquisition of Epoch	'	'	'	'	'	288	'	'	'	'	'
Correction of historical remeasurement of certain foreign cash balances	'	'	'	'	'	'	'	'	'	333	'
Correction of historical remeasurement of certain foreign cash balances, net of tax	'	'	'	'	'	'	'	'	'	222	'
Income tax expense for additional tax accounting adjustments	'	'	'	'	'	'	'	'	'	801	'
Decrease in deferred tax liabilities related to additional tax accounting adjustments	'	'	'	'	'	'	'	'	'	1,104	'
Decrease in deferred tax assets related to additional tax accounting adjustments	'	'	'	'	'	'	'	'	'	64	'
Decrease in income tax receivable related to additional tax accounting adjustments	'	'	'	'	'	'	'	'	'	891	'
Increase in cumulative translation adjustment related to additional income tax adjustments	'	'	'	'	'	'	'	'	'	950	'
Total of adjustments for the period	'	'	'	'	'	'	'	'	1,305	1,195	2,280
Diluted per share effect of total adjustments for the period (in dollars per share)	'	'	'	'	'	'	'	'	$0.05	$0.05	$0.10
Adjustment to employer-paid fringe benefits for required contributions to various plans pursuant to the annual incentive cash bonus program (AIP)	'	'	'	'	'	'	'	'	'	'	1,474
Net of tax effect of adjustment to employer-paid fringe benefits for required contributions to various plans pursuant to the annual incentive cash bonus program (AIP)	'	'	'	'	'	'	'	'	'	'	1,014
Income tax expense recorded for certain compensation in fiscal 2008 through 2010 for which a previous tax benefit should not have been recorded	'	'	'	'	'	'	'	'	'	'	671
Under accrual for annual incentive cash bonus program (AIP)	'	'	'	'	'	'	'	'	'	'	290
Net of tax effect of under accrual for annual incentive cash bonus program (AIP)	'	'	'	'	'	'	'	'	'	'	199
Reversal of deferred tax asset related to certain share-based compensation expense	'	'	'	'	'	'	'	'	'	'	497
Other immaterial corrections to deferred tax assets and liabilities that reduced income tax expense	'	'	'	'	'	'	'	'	'	'	101
Reversal of deferred tax asset related to foreign net operating losses	'	'	'	'	'	'	'	'	1,686	'	'
Reduction in income tax expense related to additional tax accounting corrections	'	'	'	'	'	'	'	'	381	'	'
Increase in deferred tax assets related to additional tax accounting adjustments	'	'	'	'	'	'	'	'	775	'	'
Increase in additional paid in capital related to additional tax accounting corrections	'	'	'	'	'	'	'	'	775	'	'
Decrease in income taxes payable related to additional tax accounting corrections	'	'	'	'	'	'	'	'	299	'	'
Decrease in deferred tax liabilities related to additional tax accounting corrections	'	'	'	'	'	'	'	'	$82	'	'

SUMMARY_OF_SIGNIFICANT_ACCOUNT3

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Details) (USD $)	3 Months Ended	12 Months Ended
In Thousands, unless otherwise specified	Mar. 31, 2012	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2011
		Segment	Segment
ACCOUNTS RECEIVABLE [Abstract]	'	'	'	'
Accounts receivable, less allowance for doubtful accounts	'	$54,640	$53,506	'
Bad debt expense related to Elpida	3,727	'	'	'
Allowance for doubtful accounts [Roll Forward]	'	'	'	'
Balance, beginning of period	'	4,757	'	'
Amounts charged to expense	'	173	3,771	-18
Deductions and adjustments	'	-3,398	'	'
Balance, end of period	'	$1,532	$4,757	'
Minimum reporting requirements for customer concentration disclosure (in hundredths)	'	10.00%	10.00%	10.00%
Goodwill and Intangible Assets [Abstract]	'	'	'	'
Number of reporting units to which goodwill and intangible assets have been allocated	'	3	3	'
Minimum [Member]	'	'	'	'
Goodwill and Intangible Assets [Abstract]	'	'	'	'
Finite-Lived Intangible Asset, Useful Life	'	'1 year	'1 year	'
Maximum [Member]	'	'	'	'
Goodwill and Intangible Assets [Abstract]	'	'	'	'
Finite-Lived Intangible Asset, Useful Life	'	'10 years 6 months	'10 years 6 months	'
Buildings [Member] | Minimum [Member]	'	'	'	'
Property, Plant and Equipment [Line Items]	'	'	'	'
Property, Plant and Equipment, Useful Life	'	'15 years	'	'
Buildings [Member] | Maximum [Member]	'	'	'	'
Property, Plant and Equipment [Line Items]	'	'	'	'
Property, Plant and Equipment, Useful Life	'	'25 years	'	'
Machinery and Equipment [Member] | Minimum [Member]	'	'	'	'
Property, Plant and Equipment [Line Items]	'	'	'	'
Property, Plant and Equipment, Useful Life	'	'3 years	'	'
Machinery and Equipment [Member] | Maximum [Member]	'	'	'	'
Property, Plant and Equipment [Line Items]	'	'	'	'
Property, Plant and Equipment, Useful Life	'	'10 years	'	'
Furniture and fixtures [Member] | Minimum [Member]	'	'	'	'
Property, Plant and Equipment [Line Items]	'	'	'	'
Property, Plant and Equipment, Useful Life	'	'5 years	'	'
Furniture and fixtures [Member] | Maximum [Member]	'	'	'	'
Property, Plant and Equipment [Line Items]	'	'	'	'
Property, Plant and Equipment, Useful Life	'	'10 years	'	'
Information Systems [Member] | Minimum [Member]	'	'	'	'
Property, Plant and Equipment [Line Items]	'	'	'	'
Property, Plant and Equipment, Useful Life	'	'3 years	'	'
Information Systems [Member] | Maximum [Member]	'	'	'	'
Property, Plant and Equipment [Line Items]	'	'	'	'
Property, Plant and Equipment, Useful Life	'	'5 years	'	'
Accounts Receivable [Member] | Taiwan Semiconductor Manufacturing Co. (TSMC) [Member]	'	'	'	'
Concentration Risk [Line Items]	'	'	'	'
Percentage of net accounts receivable concentration (in hundredths)	'	16.70%	17.10%	'
Accounts Receivable [Member] | Samsung [Member]	'	'	'	'
Concentration Risk [Line Items]	'	'	'	'
Percentage of net accounts receivable concentration (in hundredths)	'	11.80%	12.10%	'
Revenue [Member] | Taiwan Semiconductor Manufacturing Co. (TSMC) [Member]	'	'	'	'
Concentration Risk [Line Items]	'	'	'	'
Concentration of credit risk by customer (in hundredths)	'	21.00%	18.00%	17.00%
Revenue [Member] | Samsung [Member]	'	'	'	'
Concentration Risk [Line Items]	'	'	'	'
Concentration of credit risk by customer (in hundredths)	'	13.00%	13.00%	10.00%

FAIR_VALUE_OF_FINANCIAL_INSTRU2

FAIR VALUE OF FINANCIAL INSTRUMENTS, Schedule of Fair Value of Financial Instruments (Details) (Fair Value, Measurements, Recurring [Member], USD $)	Sep. 30, 2013	Sep. 30, 2012
In Thousands, unless otherwise specified
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Cash and cash equivalents	$226,029	$178,459
Auction rate securities (ARS)	7,966	7,991
Other long-term investments	1,375	1,082
Total	235,370	187,532
Level 1 [Member]	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Cash and cash equivalents	226,029	178,459
Auction rate securities (ARS)	0	0
Other long-term investments	1,375	1,082
Total	227,404	179,541
Level 2 [Member]	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Cash and cash equivalents	0	0
Auction rate securities (ARS)	0	0
Other long-term investments	0	0
Total	0	0
Level 3 [Member]	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Cash and cash equivalents	0	0
Auction rate securities (ARS)	7,966	7,991
Other long-term investments	0	0
Total	$7,966	$7,991

FAIR_VALUE_OF_FINANCIAL_INSTRU3

FAIR VALUE OF FINANCIAL INSTRUMENTS (Details) (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Sep. 30, 2013
	Security
FAIR VALUE OF FINANCIAL INSTRUMENTS [Abstract]	'
Other long-term investments, Supplemental Employee Retirement Plan (SERP)	$1,375
Corresponding SERP liability	1,375
Number of discounted cash flow analysis used to determine fair value of long-term ARS	2
Number of tax exempt municipal debt securities	2
Auction rate securities (ARS) par value	8,200
Number of impaired auction rate securities (ARS)	1
Fair value of impaired security	3,016
Par value of impaired security	3,250
Impairment amount of impaired security	234
Monetized par value of impaired security	$25

FAIR_VALUE_OF_FINANCIAL_INSTRU4

FAIR VALUE OF FINANCIAL INSTRUMENTS, Schedule of Auction Rate Securities (ARS) Activity (Details) (Auction Rate Securities [Member], USD $)	12 Months Ended
In Thousands, unless otherwise specified	Sep. 30, 2013
Auction Rate Securities [Member]	'
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]	'
Balance, beginning of period	$7,991
Net sales of ARS	-25
Balance, end of period	$7,966

INVENTORIES_Details

INVENTORIES (Details) (USD $)	Sep. 30, 2013	Sep. 30, 2012
In Thousands, unless otherwise specified
INVENTORIES [Abstract]	'	'
Raw materials	$38,004	$34,591
Work in process	5,001	6,333
Finished goods	20,781	25,548
Total	$63,786	$66,472

PROPERTY_PLANT_AND_EQUIPMENT_D

PROPERTY, PLANT AND EQUIPMENT (Details) (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2011
Property, Plant and Equipment [Line Items]	'	'	'
Total property, plant and equipment	$329,376	$341,029	'
Less: Accumulated depreciation and amortization of assets under capital leases	-217,391	-216,009	'
Net property, plant and equipment	111,985	125,020	130,791
Depreciation expense, including amortization of assets recorded under capital leases	17,835	20,863	21,271
Impairment expense	'	968	'
Impairment expense, cost of goods sold	'	842	'
Impairment expense, selling and marketing	'	126	'
Land [Member]	'	'	'
Property, Plant and Equipment [Line Items]	'	'	'
Total property, plant and equipment	18,914	21,566	'
Buildings [Member]	'	'	'
Property, Plant and Equipment [Line Items]	'	'	'
Total property, plant and equipment	97,542	101,627	'
Machinery and Equipment [Member]	'	'	'
Property, Plant and Equipment [Line Items]	'	'	'
Total property, plant and equipment	175,406	181,117	'
Furniture and fixtures [Member]	'	'	'
Property, Plant and Equipment [Line Items]	'	'	'
Total property, plant and equipment	6,234	6,417	'
Information systems [Member]	'	'	'
Property, Plant and Equipment [Line Items]	'	'	'
Total property, plant and equipment	26,208	25,346	'
Capital leases [Member]	'	'	'
Property, Plant and Equipment [Line Items]	'	'	'
Total property, plant and equipment	0	66	'
Construction in progress [Member]	'	'	'
Property, Plant and Equipment [Line Items]	'	'	'
Total property, plant and equipment	$5,072	$4,890	'

GOODWILL_AND_OTHER_INTANGIBLE_2

GOODWILL AND OTHER INTANGIBLE ASSETS (Details) (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Sep. 30, 2013		Sep. 30, 2012		Sep. 30, 2011
GOODWILL AND OTHER INTANGIBLE ASSETS [Abstract]	'		'		'
Goodwill	$44,306		$44,620		'
Finite-Lived Intangible Assets [Line Items]	'		'		'
Gross Carrying Amount subject to amortization	31,678		31,793		'
Accumulated Amortization	23,083		20,510		'
Other intangible assets [Abstract]	'		'		'
Increase (decrease) in other intangible assets due to foreign currency fluctuations	-115		553		'
Other intangible assets acquired	'		155		'
Amortization expense	2,622		2,682		2,720
Estimated future amortization expense [Abstract]	'		'		'
2014	2,497		'		'
2015	2,429		'		'
2016	2,009		'		'
2017	1,177		'		'
2018	466		'		'
Other Intangible Assets [Member]	'		'		'
Indefinite-lived Intangible Assets by Major Class [Line Items]	'		'		'
Total other intangible assets not subject to amortization	1,190	[1]	1,190	[1]	'
Total other intangible assets	32,868		32,983		'
Product Technology [Member]	'		'		'
Finite-Lived Intangible Assets [Line Items]	'		'		'
Gross Carrying Amount subject to amortization	8,362		8,387		'
Accumulated Amortization	5,853		4,902		'
Acquired Patents and Licenses [Member]	'		'		'
Finite-Lived Intangible Assets [Line Items]	'		'		'
Gross Carrying Amount subject to amortization	8,270		8,270		'
Accumulated Amortization	7,196		6,775		'
Trade Secrets and Know How [Member]	'		'		'
Finite-Lived Intangible Assets [Line Items]	'		'		'
Gross Carrying Amount subject to amortization	2,550		2,550		'
Accumulated Amortization	2,550		2,550		'
Customer relationships, distribution rights and Other [Member]	'		'		'
Finite-Lived Intangible Assets [Line Items]	'		'		'
Gross Carrying Amount subject to amortization	12,496		12,586		'
Accumulated Amortization	$7,484		$6,283		'
[1]	Total other intangible assets not subject to amortization primarily consist of trade names.

OTHER_LONGTERM_ASSETS_Details

OTHER LONG-TERM ASSETS (Details) (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Sep. 30, 2013	Sep. 30, 2012
	Security
OTHER LONG-TERM ASSETS [Abstract]	'	'
Auction rate securities	$7,966	$7,991
Other long-term assets	3,086	2,872
Other long-term investments	1,375	1,082
Total	12,427	11,945
Number of Auction rate securities classified as long-term	2	'
Number of Auction rate securities, pretax reduction maintained	1	'
Reduction in fair value Auction Rate Securities, pretax	234	'
Reduction in fair value Auction Rate Securities, net of tax	151	'
Monetization of Auction Rate Securities	25	'
Long-term liability, SERP investments	$1,375	'

ACCRUED_EXPENSES_INCOME_TAXES_2

ACCRUED EXPENSES, INCOME TAXES PAYABLE AND OTHER CURRENT LIABILITIES (Details) (USD $)	Sep. 30, 2013	Sep. 30, 2012
In Thousands, unless otherwise specified
ACCRUED EXPENSES, INCOME TAXES PAYABLE AND OTHER CURRENT LIABILITIES [Abstract]	'	'
Accrued compensation	$24,601	$18,532
Goods and services received, not yet invoiced	4,681	3,478
Deferred revenue and customer advances	458	3,341
Warranty accrual	324	359
Income taxes payable	6,931	2,843
Taxes, other than income taxes	951	1,041
Other	1,953	3,144
Total	$39,899	$32,738

DEBT_Details

DEBT (Details) (USD $)	12 Months Ended		12 Months Ended
	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2013	Sep. 30, 2013
			Revolving Credit Facility [Member]	Term Loan [Member]
Debt Instrument [Line Items]	'	'	'	'
Debt Instrument, Face Amount	'	'	'	$175,000
Line of credit facility, borrowing capacity	'	'	100,000	'
Line of Credit Facility, Additional Borrowing Capacity	'	'	75,000	'
Debt Instrument, Maturity Date	'	'	13-Feb-17	'
Line of Credit Facility Unused Capacity Commitment Fee Percentage Minimum (in hundredths)	'	'	0.25%	'
Line of Credit Facility Unused Capacity Commitment Fee Percentage Maximum (in hundredths)	'	'	0.35%	'
Debt issuance costs	2,658,000	'	'	'
Debt issuance costs, current	'	537,000	'	'
Debt issuance costs, noncurrent	'	1,273,000	'	'
Debt instrument, fair value	'	'	'	161,875,000
Maximum consolidated leverage ratio through June 30, 2014	'	'	2.75	'
Minimum consolidated fixed charge coverage ratio	'	'	1.25	'
Maximum consolidated leverage ratio after July 1, 2014	'	'	2.5	'
Actual consolidated leverage ratio	'	'	1.47	'
Actual consolidated fixed charge coverage ratio	'	'	4.9	'
Line of Credit Facility, Interest Rate Description	'	'	'In addition to paying interest on outstanding principal under the Credit Agreement, we pay a commitment fee to the lenders under the Revolving Credit Facility in respect of the unutilized commitments thereunder at a rate ranging from 0.25% to 0.35%, based on our consolidated leverage ratio.	'Borrowings under the Credit Facilities (other than in respect of swing-line loans) bear interest at a rate per annum equal to the "Applicable Rate" (as defined below) plus, at our option, either (1) a LIBOR rate determined by reference to the cost of funds for deposits in the relevant currency for the interest period relevant to such borrowing or (2) the "Base Rate", which is the highest of (x) the prime rate of Bank of America, N.A., (y) the federal funds rate plus 1/2 of 1.00% and (z) the one-month LIBOR rate plus 1.00%. The initial Applicable Rate for borrowings under the Credit Facilities was 1.75% with respect to LIBOR borrowings and 0.25% with respect to Base Rate borrowings, with such Applicable Rate subject to adjustment based on our consolidated leverage ratio. Swing-line loans will bear interest at the Base Rate plus the Applicable Rate for Base Rate loans under the Revolving Credit Facility.
Long-term Debt, by Maturity [Abstract]	'	'	'	'
2014	'	10,938,000	'	'
2015	'	15,312,000	'	'
2016	'	21,875,000	'	'
2017	'	113,750,000	'	'
Long Term Debt	'	161,875,000	'	'
Current portion of long-term debt	$10,937,000	$10,938,000	'	'

DERIVATIVE_FINANCIAL_INSTRUMEN2

DERIVATIVE FINANCIAL INSTRUMENTS (Details)	Sep. 30, 2013
	Contract
DERIVATIVE FINANCIAL INSTRUMENTS [Abstract]	'
Number of forward foreign exchange contracts held	1
Number of subsidiaries in Japan with intercompany notes	1

DERIVATIVE_FINANCIAL_INSTRUMEN3

DERIVATIVE FINANCIAL INSTRUMENTS, Schedule of Fair Value of Derivative Instruments in the Consolidated Balance Sheet (Details) (Foreign Exchange Contract [Member], Not Designated as Hedging Instrument [Member], USD $)	Sep. 30, 2013	Sep. 30, 2012
In Thousands, unless otherwise specified
Prepaid Expenses and Other Current Assets [Member]	'	'
Derivatives, Fair Value [Line Items]	'	'
Fair value of foreign exchange contract asset derivatives	$60	$38
Fair value of foreign exchange contract liability derivatives	0	0
Accrued Expenses and Other Current Liabilities [Member]	'	'
Derivatives, Fair Value [Line Items]	'	'
Fair value of foreign exchange contract asset derivatives	0	0
Fair value of foreign exchange contract liability derivatives	$0	$0

DERIVATIVE_FINANCIAL_INSTRUMEN4

DERIVATIVE FINANCIAL INSTRUMENTS, Schedule of the Effect of Derivative Instruments on the Consolidated Statement of Income (Details) (Foreign Exchange Contract [Member], Other Income (Expense), Net [Member], Not Designated as Hedging Instrument [Member], USD $)	12 Months Ended
In Thousands, unless otherwise specified	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2011
Foreign Exchange Contract [Member] | Other Income (Expense), Net [Member] | Not Designated as Hedging Instrument [Member]	'	'	'
Derivative Instruments, Gain (Loss) [Line Items]	'	'	'
Gain (loss) recognized in statement of income	$252	$154	($806)

SHAREBASED_COMPENSATION_PLANS_1

SHARE-BASED COMPENSATION PLANS (Details) (USD $)

3 Months Ended

12 Months Ended

12 Months Ended

12 Months Ended

12 Months Ended

12 Months Ended

12 Months Ended

In Thousands, except Share data, unless otherwise specified

Mar. 31, 2013

Sep. 30, 2013

Sep. 30, 2012

Sep. 30, 2011

Mar. 02, 2012

Mar. 01, 2012

Sep. 30, 2013

Sep. 30, 2012

Sep. 30, 2011

Sep. 30, 2013

Sep. 30, 2012

Sep. 30, 2011

Sep. 30, 2013

Sep. 30, 2012

Sep. 30, 2011

Sep. 30, 2013

Sep. 30, 2012

Sep. 30, 2011

Sep. 30, 2013

Sep. 30, 2012

Sep. 30, 2013

Sep. 30, 2012

Sep. 30, 2011

Sep. 30, 2013

Sep. 30, 2013

Sep. 30, 2012

Sep. 30, 2011

Mar. 31, 2008

Feb. 29, 2008

Mar. 02, 2012

Mar. 01, 2012

Sep. 30, 2013

Sep. 30, 2012

Sep. 30, 2011

Mar. 02, 2012

Mar. 01, 2012

Sep. 30, 2013

Sep. 30, 2012

Sep. 30, 2011

Mar. 02, 2012

Mar. 01, 2012

Sep. 30, 2013

Sep. 30, 2013

Director

Cost of Goods Sold [Member]

Cost of Goods Sold [Member]

Cost of Goods Sold [Member]

Research, Development and technical [Member]

Research, Development and technical [Member]

Research, Development and technical [Member]

Selling and Marketing [Member]

Selling and Marketing [Member]

Selling and Marketing [Member]

General and Administrative [Member]

General and Administrative [Member]

General and Administrative [Member]

Directors' Deferred Compensation Plan [Member]

Directors' Deferred Compensation Plan [Member]

Director [Member]

Director [Member]

Director [Member]

Deposit Share Plan [Member]

Employee Stock Purchase Plan [Member]

Employee Stock Purchase Plan [Member]

Employee Stock Purchase Plan [Member]

Employee Stock Purchase Plan [Member]

Employee Stock Purchase Plan [Member]

Directors' Deferred Compensation Plan [Member]

Directors' Deferred Compensation Plan [Member]

Stock Options [Member]

Stock Options [Member]

Stock Options [Member]

Stock Options [Member]

Stock Options [Member]

Restricted Stock [Member]

Restricted Stock [Member]

Restricted Stock [Member]

Restricted Stock [Member]

Restricted Stock [Member]

Other than Options or SARs [Member]

Incentive Stock Options [Member]

Directors' Deferred Compensation Plan [Member]

Directors' Deferred Compensation Plan [Member]

Directors' Deferred Compensation Plan [Member]

Omnibus Incentive Plan [Abstract]

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Number of shares authorized for issuance (in shares)

'

4,934,444

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

730,023

'

'

975,000

475,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Number of shares authorized other than options or Sars (in shares)

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

2,030,952

'

Number of shares authorized for incentive stock options (in shares)

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

2,538,690

Number of shares authorized under newly issued plan (in shares)

'

2,901,360

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Number of shares available under previously existing plan (in shares)

'

2,033,084

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Special cash dividend, leveraged recapitalization (in dollars per share)

'

'

'

'

$15

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

$15

'

'

'

'

$15

'

'

'

'

$15

'

'

'

Recapitalization ratio

'

'

'

'

1.45068

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

1.45068

'

'

'

'

1.45068

'

'

'

'

1.45068

'

'

'

Closing price on dividend payment date (in dollars per share)

'

'

'

'

'

$51.92

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

$51.92

'

'

'

'

$51.92

'

'

'

'

$51.92

'

'

Opening price on ex-dividend date (in dollars per share)

'

'

'

'

$35.79

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

$35.79

'

'

'

'

$35.79

'

'

'

'

$35.79

'

'

'

Stock based compensation, contractual term (in years)

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'10 years

'

'

'

'

'

'

'

'

'

'

'

Stock based compensation, vesting period (in years)

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'4 years

'

'

'

'

'4 years

'

'

'

'

'

'

Share based compensation expense

'

$13,350

$13,306

$12,646

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

$584

$735

$508

'

'

'

'

$6,878

$6,802

$6,871

'

'

$5,793

$5,674

$5,184

'

'

'

'

Deposit share plan match in restricted shares (in hundredths)

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

50.00%

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Employee stock purchase plan [Abstract]

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Percentage annual earnings withheld to purchase stock, maximum (in hundredths)

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

10.00%

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Maximum discounted stock purchase price (in hundredths)

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

85.00%

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Reduction in stock purchase price due to leveraged recapitalization, maximum

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

68.93%

'

'

'

'

'

'

'

'

'

'

'

Number of shares issued, employee stock ownership plan (in shares)

'

84,602

70,645

61,364

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

84,602

70,645

61,364

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Percent vested in first year for non employee directors (in hundredths)

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

100.00%

'

'

'

'

'

'

'

'

'

'

'

Share based compensation arrangements, Fair value assumptions and methodology [Abstract]

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Weighted-average grant date fair value (in dollars per share)

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

$12.13

$15.66

$16.49

'

'

'

'

'

'

'

'

'

Weighted-average grant date fair value - ESPP (in dollars per share)

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

$7.41

$8.78

$9.05

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Expected term (in years)

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'6 months

'6 months

'6 months

'

'

'

'

'6 years 4 months 13 days

'6 years 4 months 17 days

'6 years 3 months 11 days

'

'

'

'

'

'

'

'

'

Expected volatility (in hundredths)

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

25.00%

36.00%

28.00%

'

'

'

'

36.00%

38.00%

36.00%

'

'

'

'

'

'

'

'

'

Risk-free rate of return (in hundredths)

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

0.10%

0.10%

0.20%

'

'

'

'

0.90%

1.30%

2.10%

'

'

'

'

'

'

'

'

'

Dividend yield (in hundredths)

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

0.00%

0.00%

0.00%

'

'

'

'

0.00%

0.00%

0.00%

'

'

'

'

'

'

'

'

'

Stock Options Activity [Roll Forward]

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Outstanding, beginning of period (in shares)

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

5,133,626

'

'

'

'

'

'

'

'

'

'

'

Granted (in shares)

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

533,424

'

'

'

'

'

'

'

'

'

'

'

Exercised (in shares)

'

-1,071,750

-976,645

-1,085,965

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

-1,071,750

'

'

'

'

'

'

'

'

'

'

'

Forfeited or canceled (in shares)

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

-321,413

'

'

'

'

'

'

'

'

'

'

'

Outstanding, end of period (in shares)

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

4,273,887

5,133,626

'

'

'

'

'

'

'

'

'

'

Exercisable, end of period ( in shares)

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

2,881,901

'

'

'

'

'

'

'

'

'

'

'

Expected to vest, end of period (in shares)

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

1,321,760

'

'

'

'

'

'

'

'

'

'

'

Weighted Average Exercise Price [Roll Forward]

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Weighted average exercise price, outstanding, beginning of period (in dollars per share)

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

$26.75

'

'

'

'

'

'

'

'

'

'

'

Weighted average exercise price, granted (in dollars per share)

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

$32.89

'

'

'

'

'

'

'

'

'

'

'

Weighted average exercise price, exercised (in dollars per share)

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

$26.61

'

'

'

'

'

'

'

'

'

'

'

Weighted average exercise price, forfeited or canceled (in dollars per share)

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

$34.72

'

'

'

'

'

'

'

'

'

'

'

Weighted average exercise price, outstanding, end of period (in dollars per share)

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

$26.95

$26.75

'

'

'

'

'

'

'

'

'

'

Weighted average exercise price, exercisable, end of period (in dollars per share)

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

$25.82

'

'

'

'

'

'

'

'

'

'

'

Weighted average exercise price, expected to vest, end of period (in dollars per share)

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

$29.53

'

'

'

'

'

'

'

'

'

'

'

Additional Disclosures [Abstract]

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Weighted average remaining contractual term, outstanding, end of period (in years)

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'5 years 2 months 12 days

'

'

'

'

'

'

'

'

'

'

'

Weighted average remaining contractual term, exercisable, end of period (in years)

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'3 years 8 months 12 days

'

'

'

'

'

'

'

'

'

'

'

Weighted average remaining contractual term, expected to vest, end of period (in years)

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'8 years 2 months 12 days

'

'

'

'

'

'

'

'

'

'

'

Aggregate intrinsic value, outstanding, end of period

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

49,410

'

'

'

'

'

'

'

'

'

'

'

Aggregate intrinsic value, exercisable, end of period

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

36,568

'

'

'

'

'

'

'

'

'

'

'

Aggregate intrinsic value, expected to vest, end of period

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

11,870

'

'

'

'

'

'

'

'

'

'

'

Closing stock price (in dollars per share)

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

$38.51

'

'

'

'

'

'

'

'

'

'

'

Total intrinsic value of options exercised

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

9,847

6,879

13,135

'

'

'

'

'

'

'

'

'

Cash received from options exercised

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

28,525

34,107

35,955

'

'

'

'

'

'

'

'

'

Actual tax benefit realized for the tax deductions from options exercised

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

3,394

2,239

4,401

'

'

'

'

'

'

'

'

'

Total fair value of stock options vested

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

6,681

6,796

6,321

'

'

'

'

'

'

'

'

'

Total unrecognized share-based compensation expense

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

9,697

'

'

'

'

8,521

'

'

'

'

'

'

Compensation cost, weighted-average period for recognition (in years)

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'2 years 4 months 24 days

'

'

'

'

'2 years 6 months

'

'

'

'

'

'

Restricted stock and restricted stock awards units [Roll Forward]

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Restricted stocks awards and units, nonvested, beginning of period (in shares)

'

394,124

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Restricted stocks awards and units, granted (in shares)

'

184,581

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Restricted stocks awards and units, vested (in shares)

'

-174,362

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Restricted stocks awards and units, forfeited (in shares)

'

-7,914

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Restricted stocks awards and units, nonvested, end of period (in shares)

'

396,429

394,124

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Weighted Average Grant Date Fair Value [Roll Forward]

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Weighted average grant date fair value, nonvested, beginning of period (in dollars per share)

'

$34.15

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Weighted average grant date fair value, granted (in dollars per share)

'

$32.94

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Weighted average grant date fair value, vested (in dollars per share)

'

$31.30

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Weighted average grant date fair value, forfeited (in dollars per share)

'

$34.23

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Weighted average grant date fair value, nonvested, end of period (in dollars per share)

'

$34.84

$34.15

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Total fair values of restricted stock awards and restricted stock units vested

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

5,457

5,784

4,452

'

'

'

'

Directors' deferred compensation plan [Abstract]

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Cumulative number of shares deferred (in shares)

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

74,469

71,781

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Compensation expense - deferred compensation arrangement

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

95

95

83

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Stock based compensation expense

'

'

'

'

'

'

1,707

1,541

1,221

1,301

1,105

1,060

1,367

1,392

1,124

8,975

9,268

9,241

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Stock based compensation - tax benefit

'

-4,581

-4,118

-4,060

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Total share-based compensation expense, net of tax

'

8,769

9,188

8,586

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Number of non-employee directors who have completed two full terms of service

5

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Fair value of awards for completing minimum full terms of service

$755

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Number of non-employee directors subject to a full one year vesting period

3

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

SAVINGS_PLAN_Details

SAVINGS PLAN (Details) (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2011
SAVINGS PLAN [Abstract]	'	'	'
Maximum participants' contributions as a percentage of their eligible compensation (in hundredths)	60.00%	'	'
Company's matching contribution on participants' first four percent contribution (in hundredths)	100.00%	'	'
Company's matching contribution on participants' contributions over two percent (in hundredths)	50.00%	'	'
Percentage of participant's contribution subject to company's one hundred percent matching contribution (in hundredths)	4.00%	'	'
Percentage of participant's contribution subject to company's fifty percent matching contribution	2.00%	'	'
401(k) Plan expense	$4,057	$4,210	$4,201
Percentage of company's contribution vested at the time of contribution (in hundredths)	100.00%	'	'

OTHER_INCOME_EXPENSE_NET_Detai

OTHER INCOME (EXPENSE), NET (Details) (USD $)	3 Months Ended								12 Months Ended
In Thousands, unless otherwise specified	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2011	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2011
Other Income (Expense) Net [Line Items]	'	'	'	'	'	'	'	'	'	'	'
Total other income (expense), net	($173)	$248	$463	$854	($681)	($864)	$97	$104	$1,392	($1,344)	($1,318)
Interest Income [Member]	'	'	'	'	'	'	'	'	'	'	'
Other Income (Expense) Net [Line Items]	'	'	'	'	'	'	'	'	'	'	'
Total other income (expense), net	'	'	'	'	'	'	'	'	145	146	238
Other Income (Expense) [Member]	'	'	'	'	'	'	'	'	'	'	'
Other Income (Expense) Net [Line Items]	'	'	'	'	'	'	'	'	'	'	'
Total other income (expense), net	'	'	'	'	'	'	'	'	$1,247	($1,490)	($1,556)

STOCKHOLDERS_EQUITY_Details

STOCKHOLDERS EQUITY (Details) (USD $)	12 Months Ended			3 Months Ended	12 Months Ended
In Thousands, except Share data, unless otherwise specified	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2011	Dec. 13, 2011	Sep. 30, 2013	Sep. 30, 2011	Sep. 30, 2011
				Current Repurchase Program [Member]	Current Repurchase Program [Member]	Current Repurchase Program [Member]	Prior Repurchase Program [Member]
Capital Stock Activity [Rollforward]	'	'	'	'	'	'	'
Beginning Balance (in shares)	28,864,527	27,652,336	26,384,715	'	'	'	'
Exercise of stock options (in shares)	1,071,750	976,645	1,085,965	'	'	'	'
Restricted stock under EIP, net of forfeitures (in shares)	185,925	159,879	115,069	'	'	'	'
Restricted stock under Deposit Share Plan, net of forfeitures (in shares)	6,773	5,022	5,223	'	'	'	'
Common stock under ESPP (in shares)	84,602	70,645	61,364	'	'	'	'
Ending Balance (in shares)	30,213,577	28,864,527	27,652,336	'	'	'	'
Treasury Stock [Abstract]	'	'	'	'	'	'	'
Beginning Balance (in shares)	5,682,288	4,715,577	3,446,069	'	'	'	'
Repurchases of common stock under share repurchase plans (in shares)	1,144,836	929,407	1,235,668	'	'	671,100	564,568
Repurchases of common stock - other (in shares)	39,551	37,304	33,840	'	'	'	'
Ending Balance (in shares)	6,866,675	5,682,288	4,715,577	'	'	'	'
Share repurchase program, value of shares authorized to be repurchased	'	'	'	$125,000	$150,000	'	'
Share repurchase program, remaining authorized repurchase amount	'	'	'	82,869	90,000	'	'
Cost of shares repurchased	$40,000	$33,026	$54,106	'	'	$29,105	$25,000
Number of votes each common stockholder is entitled to on matter submitted to a vote of stockholders	1	'	'	'	'	'	'
Number of authorized shares of common stock (in shares)	200,000,000	200,000,000	'	'	'	'	'

INCOME_TAXES_Details

INCOME TAXES (Details) (USD $)	3 Months Ended								12 Months Ended
	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2011	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2011
Income (loss) from continuing operations before income taxes [Abstract]	'	'	'	'	'	'	'	'	'	'	'
Domestic	'	'	'	'	'	'	'	'	$40,045,000	$55,555,000	$54,886,000
Foreign	'	'	'	'	'	'	'	'	34,175,000	7,316,000	24,026,000
Total	22,574,000	21,555,000	13,530,000	16,561,000	18,835,000	19,829,000	8,855,000	15,352,000	74,220,000	62,871,000	78,912,000
U.S. federal and state [Abstract]	'	'	'	'	'	'	'	'	'	'	'
Current	'	'	'	'	'	'	'	'	17,649,000	19,975,000	15,700,000
Deferred	'	'	'	'	'	'	'	'	-3,576,000	-308,000	6,194,000
Total	'	'	'	'	'	'	'	'	14,073,000	19,667,000	21,894,000
Foreign [Abstract]	'	'	'	'	'	'	'	'	'	'	'
Current	'	'	'	'	'	'	'	'	8,304,000	5,593,000	6,616,000
Deferred	'	'	'	'	'	'	'	'	458,000	-3,215,000	-1,260,000
Total	'	'	'	'	'	'	'	'	8,762,000	2,378,000	5,356,000
Total U.S. and foreign	5,805,000	6,062,000	4,110,000	6,858,000	7,196,000	6,587,000	3,325,000	4,937,000	22,835,000	22,045,000	27,250,000
Effective income tax rate reconciliation [Abstract]	'	'	'	'	'	'	'	'	'	'	'
Federal statutory rate (in hundredths)	'	'	'	'	'	'	'	'	35.00%	35.00%	35.00%
U.S. benefits from research and experimentation activities (in hundredths)	'	'	'	'	'	'	'	'	-2.00%	-0.50%	-2.00%
State taxes, net of federal effect (in hundredths)	'	'	'	'	'	'	'	'	0.30%	0.20%	0.60%
Foreign income at other than U.S. rates (in hundredths)	'	'	'	'	'	'	'	'	-3.10%	-1.90%	-2.80%
Change in valuation allowance (in hundredths)	'	'	'	'	'	'	'	'	1.40%	1.10%	0.00%
Executive compensation (in hundredths)	'	'	'	'	'	'	'	'	0.20%	0.80%	1.40%
Share-based compensation (in hundredths)	'	'	'	'	'	'	'	'	0.10%	0.70%	3.30%
Adjustment of prior amounts (in hundredths)	'	'	'	'	'	'	'	'	-0.20%	-0.20%	0.00%
Domestic production deduction (in hundredths)	'	'	'	'	'	'	'	'	-0.20%	-0.50%	-0.80%
Tax-exempt interest income (in hundredths)	'	'	'	'	'	'	'	'	0.00%	0.00%	-0.10%
Other, net (in hundredths)	'	'	'	'	'	'	'	'	-0.70%	0.40%	-0.10%
Provision for income taxes (in hundredths)	'	'	'	'	'	'	'	'	30.80%	35.10%	34.50%
Undistributed earnings of foreign subsidiaries	60,300,000	'	'	'	'	'	'	'	60,300,000	'	'
Adjustments to correct prior period tax expense amounts	'	'	'	'	'	'	'	'	'	973,000	671,000
Reversal of deferred tax asset related to certain share-based compensation expense	'	'	'	'	'	'	'	'	'	'	497,000
Foreign income tax adjustment	'	'	'	'	'	'	'	'	1,686,000	'	'
Decrease in income tax expense for election to permanently reinvest the earnings of certain foreign subsidiaries	'	'	'	'	'	'	'	'	1,810,000	'	'
Research and development tax credit	'	'	947,000	'	'	'	'	'	1,518,000	'	'
Valuation allowance on former equity investment	'	'	1,015,000	'	'	'	'	'	'	'	'
Reconciliation of gross unrecognized tax benefits [Roll Forward]	'	'	'	'	'	'	'	'	'	'	'
Beginning balance	'	'	'	283,000	'	'	'	603,000	283,000	603,000	173,000
Additions for tax positions relating to the current fiscal year	'	'	'	'	'	'	'	'	228,000	51,000	123,000
Additions for tax positions relating to prior fiscal years	'	'	'	'	'	'	'	'	247,000	114,000	307,000
Settlements with taxing authorities	'	'	'	'	'	'	'	'	0	-353,000	0
Lapse of statute of limitations	'	'	'	'	'	'	'	'	0	-132,000	0
Ending balance	758,000	'	'	'	283,000	'	'	'	758,000	283,000	603,000
Accrued interest and penalties on uncertain tax positions	60,000	'	'	'	4,000	'	'	'	60,000	4,000	'
Deferred tax assets [Abstract]	'	'	'	'	'	'	'	'	'	'	'
Employee benefits	3,892,000	'	'	'	4,035,000	'	'	'	3,892,000	4,035,000	'
Inventory	3,138,000	'	'	'	2,930,000	'	'	'	3,138,000	2,930,000	'
Bad debt reserve	515,000	'	'	'	1,708,000	'	'	'	515,000	1,708,000	'
Share-based compensation expense	13,907,000	'	'	'	12,659,000	'	'	'	13,907,000	12,659,000	'
Net operating losses	759,000	'	'	'	2,292,000	'	'	'	759,000	2,292,000	'
Other	2,723,000	'	'	'	2,656,000	'	'	'	2,723,000	2,656,000	'
Valuation allowance	-2,288,000	'	'	'	-1,378,000	'	'	'	-2,288,000	-1,378,000	'
Total deferred tax assets	22,646,000	'	'	'	24,902,000	'	'	'	22,646,000	24,902,000	'
Deferred tax liabilities [Abstract]	'	'	'	'	'	'	'	'	'	'	'
Translation adjustment	3,247,000	'	'	'	7,966,000	'	'	'	3,247,000	7,966,000	'
Depreciation and amortization	2,046,000	'	'	'	3,776,000	'	'	'	2,046,000	3,776,000	'
Unremitted foreign earnings	0	'	'	'	1,810,000	'	'	'	0	1,810,000	'
Other	962,000	'	'	'	645,000	'	'	'	962,000	645,000	'
Total deferred tax liabilities	6,255,000	'	'	'	14,197,000	'	'	'	6,255,000	14,197,000	'
Carryforwards [Line Items]	'	'	'	'	'	'	'	'	'	'	'
Operating Loss Carryforwards, Valuation Allowance	1,649,000	'	'	'	'	'	'	'	1,649,000	'	'
Operating loss carryforwards expiration dates	'	'	'	'	'	'	'	'	'fiscal year 2017 through fiscal year 2032	'	'
Tax holiday rate percentage (in hundredths)	0.00%	'	'	'	'	'	'	'	0.00%	'	'
Percentage of local statutory rate in effect for 2016 and 2017	50.00%	'	'	'	'	'	'	'	50.00%	'	'
Approximate tax provision reduction as a result in the tax holiday	'	'	'	'	'	'	'	'	467,000	'	'
Capital Loss Carryforward [Member]	'	'	'	'	'	'	'	'	'	'	'
Carryforwards [Line Items]	'	'	'	'	'	'	'	'	'	'	'
Tax Credit Carryforward, Amount	2,849,000	'	'	'	'	'	'	'	2,849,000	'	'
Tax Credit Carryforward, Valuation Allowance	1,015,000	'	'	'	'	'	'	'	1,015,000	'	'
Internal Revenue Service (IRS) [Member]	'	'	'	'	'	'	'	'	'	'	'
Income Tax Examination [Line Items]	'	'	'	'	'	'	'	'	'	'	'
Tax periods open to examination by taxing authorities (years)	'fiscal years 2010 through 2013	'	'	'	'	'	'	'	'fiscal years 2010 through 2013	'	'
State and Local Jurisdiction [Member]	'	'	'	'	'	'	'	'	'	'	'
Income Tax Examination [Line Items]	'	'	'	'	'	'	'	'	'	'	'
Tax periods open to examination by taxing authorities (years)	'fiscal years 2009 through 2013	'	'	'	'	'	'	'	'fiscal years 2009 through 2013	'	'
Carryforwards [Line Items]	'	'	'	'	'	'	'	'	'	'	'
Gross operating loss carryforward amounts	449,000	'	'	'	'	'	'	'	449,000	'	'
Tax Credit Carryforward, Amount	1,827,000	'	'	'	'	'	'	'	1,827,000	'	'
Tax Credit Carryforward, Valuation Allowance	942,000	'	'	'	'	'	'	'	942,000	'	'
Foreign Country [Member]	'	'	'	'	'	'	'	'	'	'	'
Income Tax Examination [Line Items]	'	'	'	'	'	'	'	'	'	'	'
Tax periods open to examination by taxing authorities (years)	'fiscal years 2009 through 2013	'	'	'	'	'	'	'	'fiscal years 2009 through 2013	'	'
Carryforwards [Line Items]	'	'	'	'	'	'	'	'	'	'	'
Gross operating loss carryforward amounts	$5,375,000	'	'	'	'	'	'	'	$5,375,000	'	'

COMMITMENTS_AND_CONTINGENCIES_1

COMMITMENTS AND CONTINGENCIES (Details) (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2011
Movement in standard product warranty accrual [Roll Forward]	'	'	'
Balance as of September 30, 2012	$359	'	'
Reserve for product warranty during the reporting period	874	'	'
Settlement of warranty	-909	'	'
Balance as of September 30, 2013	324	359	'
Lease commitments [Abstract]	'	'	'
Expiration of cancelable and noncancelable leases, maximum (in years)	6	'	'
Rent expense under operating leases	2,594	3,199	2,934
Initial present value of the minimum quarterly payments for the capital lease	9,776	'	'
Term of contract (in years)	4	'	'
Operating leases, future minimum payments due:	'	'	'
2014	2,907	'	'
2015	1,775	'	'
2016	1,583	'	'
2017	1,195	'	'
2018	157	'	'
Thereafter	450	'	'
Operating leases, total	8,067	'	'
Purchase obligations [Abstract]	'	'	'
Contractual commitments for fumed silica and fumed alumina under purchase obligations	110,576	'	'
Defined Benefit Plan Disclosure [Line Items]	'	'	'
Projected benefit obligation	4,843	5,641	'
Accumulated benefit obligation	3,631	4,183	'
Weighted average discount rate (in hundredths)	1.75%	1.75%	'
Expected rate of compensation increase (In hundredths)	2.00%	2.00%	'
Pension costs in accumulated other comprehensive income	$665	$672	'

EARNINGS_PER_SHARE_Details

EARNINGS PER SHARE (Details) (USD $)	3 Months Ended								12 Months Ended
In Thousands, except Share data, unless otherwise specified	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2011	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2011
Numerator:	'	'	'	'	'	'	'	'	'	'	'
Net income	'	'	'	'	'	'	'	'	$51,385	$40,826	$51,662
Undistributed Earnings Allocated to Participating Securities	'	'	'	'	'	'	'	'	-494	0	0
Net Income (Loss) Attributable to Parent, Total	'	'	'	'	'	'	'	'	$50,891	$40,826	$51,662
Denominator:	'	'	'	'	'	'	'	'	'	'	'
Weighted-average common shares (Denominator for basic calculation, in shares)	23,041,000	22,951,000	22,974,000	22,845,000	22,920,000	23,120,000	22,768,000	22,508,000	22,924,056	22,506,408	22,895,568
Weighted-average effect of dilutive securities:	'	'	'	'	'	'	'	'	'	'	'
Share-based compensation (in shares)	'	'	'	'	'	'	'	'	836,010	773,890	539,036
Diluted-weighted average common shares (Denominator for diluted calculation, in shares)	23,994,000	23,776,000	23,871,000	23,658,000	23,706,000	23,939,000	23,780,000	22,926,000	23,760,066	23,280,298	23,434,604
Earnings per share:	'	'	'	'	'	'	'	'	'	'	'
Basic (in dollars per share)	$0.72	$0.68	$0.41	$0.42	$0.51	$0.57	$0.24	$0.46	$2.22	$1.81	$2.26
Diluted (in dollars per share)	$0.69	$0.65	$0.40	$0.41	$0.49	$0.55	$0.23	$0.45	$2.14	$1.75	$2.20
Outstanding stock options excluded from diluted earnings (in shares)	'	'	'	'	'	'	'	'	1,500,000	1,300,000	1,300,000

FINANCIAL_INFORMATION_BY_INDUS2

FINANCIAL INFORMATION BY INDUSTRY SEGMENT, GEOGRAPHIC AREA AND PRODUCT LINE (Details) (USD $)	3 Months Ended								12 Months Ended
In Thousands, unless otherwise specified	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2011	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2011
Revenues from External Customers and Long-Lived Assets [Line Items]	'	'	'	'	'	'	'	'	'	'	'
Revenue	$116,266	$109,968	$100,364	$106,533	$110,621	$115,678	$99,236	$102,122	$433,131	$427,657	$445,442
Property, plant and equipment, net	111,985	'	'	'	125,020	'	'	'	111,985	125,020	130,791
United States [Member]	'	'	'	'	'	'	'	'	'	'	'
Revenues from External Customers and Long-Lived Assets [Line Items]	'	'	'	'	'	'	'	'	'	'	'
Revenue	'	'	'	'	'	'	'	'	53,955	56,770	61,540
Property, plant and equipment, net	47,436	'	'	'	49,325	'	'	'	47,436	49,325	50,503
Asia [Member]	'	'	'	'	'	'	'	'	'	'	'
Revenues from External Customers and Long-Lived Assets [Line Items]	'	'	'	'	'	'	'	'	'	'	'
Revenue	'	'	'	'	'	'	'	'	347,797	342,958	356,074
Property, plant and equipment, net	64,546	'	'	'	75,690	'	'	'	64,546	75,690	80,280
Europe [Member]	'	'	'	'	'	'	'	'	'	'	'
Revenues from External Customers and Long-Lived Assets [Line Items]	'	'	'	'	'	'	'	'	'	'	'
Revenue	'	'	'	'	'	'	'	'	31,379	27,929	27,828
Property, plant and equipment, net	$3	'	'	'	$5	'	'	'	$3	$5	$8

FINANCIAL_INFORMATION_BY_INDUS3

FINANCIAL INFORMATION BY INDUSTRY SEGMENT, GEOGRAPHIC AREA AND PRODUCT LINE, REVENUE BY MAJOR CUSTOMERS (Details) (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Sep. 30, 2013		Sep. 30, 2012		Sep. 30, 2011
Revenue, Major Customer [Line Items]	'		'		'
Threshold for reporting revenues by customer (in hundredths)	10.00%		10.00%		10.00%
Taiwan [Member]	'		'		'
Revenue, Major Customer [Line Items]	'		'		'
Revenue	133,273		124,732		132,089
South Korea [Member]	'		'		'
Revenue, Major Customer [Line Items]	'		'		'
Revenue	73,778		68,573		56,321
Japan [Member]	'		'		'
Revenue, Major Customer [Line Items]	'		'		'
Revenue	'	[1]	56,488		57,889
Singapore [Member]	'		'		'
Revenue, Major Customer [Line Items]	'		'		'
Revenue	'	[1]	'	[1]	47,441
[1]	Denotes less than ten percent of total

FINANCIAL_INFORMATION_BY_INDUS4

FINANCIAL INFORMATION BY INDUSTRY SEGMENT, GEOGRAPHIC AREA AND PRODUCT LINE, LONG-LIVED ASSETS BY MAJOR CUSTOMERS (Details) (USD $)	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2011
In Thousands, unless otherwise specified
Japan [Member]	'	'	'
Segment Reporting, Schedule of Long-Lived Assets by Major Customers, by Reporting Segments [Line Items]	'	'	'
Property, plant and equipment, net	$33,566	$43,411	$50,236
Taiwan [Member]	'	'	'
Segment Reporting, Schedule of Long-Lived Assets by Major Customers, by Reporting Segments [Line Items]	'	'	'
Property, plant and equipment, net	17,212	18,397	17,577
South Korea [Member]	'	'	'
Segment Reporting, Schedule of Long-Lived Assets by Major Customers, by Reporting Segments [Line Items]	'	'	'
Property, plant and equipment, net	$12,591	$12,580	'	[1]
[1]	Denotes less than ten percent of total

FINANCIAL_INFORMATION_BY_INDUS5

FINANCIAL INFORMATION BY INDUSTRY SEGMENT, GEOGRAPHIC AREA AND PRODUCT LINE, SEGMENT REPORTING INFORMATION BY PRODUCT TYPE (Details) (USD $)	3 Months Ended								12 Months Ended
In Thousands, unless otherwise specified	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2011	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2011
Revenue from External Customer [Line Items]	'	'	'	'	'	'	'	'	'	'	'
Revenue	$116,266	$109,968	$100,364	$106,533	$110,621	$115,678	$99,236	$102,122	$433,131	$427,657	$445,442
Tungsten slurries [Member]	'	'	'	'	'	'	'	'	'	'	'
Revenue from External Customer [Line Items]	'	'	'	'	'	'	'	'	'	'	'
Revenue	'	'	'	'	'	'	'	'	155,904	161,756	164,098
Dielectric slurries [Member]	'	'	'	'	'	'	'	'	'	'	'
Revenue from External Customer [Line Items]	'	'	'	'	'	'	'	'	'	'	'
Revenue	'	'	'	'	'	'	'	'	123,180	119,320	121,543
Other Metals slurries [Member]	'	'	'	'	'	'	'	'	'	'	'
Revenue from External Customer [Line Items]	'	'	'	'	'	'	'	'	'	'	'
Revenue	'	'	'	'	'	'	'	'	76,367	67,157	76,285
Polishing pads [Member]	'	'	'	'	'	'	'	'	'	'	'
Revenue from External Customer [Line Items]	'	'	'	'	'	'	'	'	'	'	'
Revenue	'	'	'	'	'	'	'	'	32,996	33,725	31,045
Engineered Surface Finishes [Member]	'	'	'	'	'	'	'	'	'	'	'
Revenue from External Customer [Line Items]	'	'	'	'	'	'	'	'	'	'	'
Revenue	'	'	'	'	'	'	'	'	23,999	24,878	24,685
Data storage slurries [Member]	'	'	'	'	'	'	'	'	'	'	'
Revenue from External Customer [Line Items]	'	'	'	'	'	'	'	'	'	'	'
Revenue	'	'	'	'	'	'	'	'	$20,685	$20,821	$27,786

SELECTED_QUARTERLY_INFORMATION1

SELECTED QUARTERLY INFORMATION (Details) (USD $)	3 Months Ended								12 Months Ended
In Thousands, except Share data, unless otherwise specified	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2011	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2011
SELECTED QUARTERLY INFORMATION [Abstract]	'	'	'	'	'	'	'	'	'	'	'
Revenue	$116,266	$109,968	$100,364	$106,533	$110,621	$115,678	$99,236	$102,122	$433,131	$427,657	$445,442
Cost of goods sold	57,143	55,359	52,019	56,494	56,883	60,462	53,442	52,843	221,015	223,630	231,336
Gross profit	59,123	54,609	48,345	50,039	53,738	55,216	45,794	49,279	212,116	204,027	214,106
Operating expenses:	'	'	'	'	'	'	'	'	'	'	'
Research, development and technical	15,835	15,149	15,073	15,316	15,401	15,415	14,071	13,755	61,373	58,642	58,035
Selling and marketing	7,360	6,470	7,046	7,109	7,288	7,458	7,434	7,336	27,985	29,516	29,758
General and administrative	12,270	10,776	12,287	10,954	10,572	10,695	15,177	12,901	46,287	49,345	45,928
Total operating expenses	35,465	32,395	34,406	33,379	33,261	33,568	36,682	33,992	135,645	137,503	133,721
Operating income (loss)	23,658	22,214	13,939	16,660	20,477	21,648	9,112	15,287	76,471	66,524	80,385
Interest expense	911	907	872	953	961	955	354	39	3,643	2,309	155
Other income (expense), net	-173	248	463	854	-681	-864	97	104	1,392	-1,344	-1,318
Income (loss) before income taxes	22,574	21,555	13,530	16,561	18,835	19,829	8,855	15,352	74,220	62,871	78,912
Provision for income taxes	5,805	6,062	4,110	6,858	7,196	6,587	3,325	4,937	22,835	22,045	27,250
Net income (loss)	$16,769	$15,493	$9,420	$9,703	$11,639	$13,242	$5,530	$10,415	$51,385	$40,826	$51,662
Basic earnings (loss) per share (in dollars per share)	$0.72	$0.68	$0.41	$0.42	$0.51	$0.57	$0.24	$0.46	$2.22	$1.81	$2.26
Weighted average basic shares outstanding (in shares)	23,041,000	22,951,000	22,974,000	22,845,000	22,920,000	23,120,000	22,768,000	22,508,000	22,924,056	22,506,408	22,895,568
Diluted earnings (loss) per share (in dollars per share)	$0.69	$0.65	$0.40	$0.41	$0.49	$0.55	$0.23	$0.45	$2.14	$1.75	$2.20
Weighted average diluted shares outstanding (in shares)	23,994,000	23,776,000	23,871,000	23,658,000	23,706,000	23,939,000	23,780,000	22,926,000	23,760,066	23,280,298	23,434,604
Dividends per share (in dollars per share)	$0	$0	$0	$0	$0	$0	$15	$0	$0	$15	$0

SCHEDULE_IIVALUATION_AND_QUALI

SCHEDULE II-VALUATION AND QUALIFYING ACCOUNTS (Details) (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2011
Allowance for Doubtful Accounts [Member]	'	'	'
Valuation and Qualifying Accounts Disclosure [Line Items]	'	'	'
Balance at beginning of year	$4,757	$1,090	$1,121
Amounts charged to expenses	173	3,771	-18
Deductions and adjustments	-3,398	-104	-13
Balance at end of year	1,532	4,757	1,090
Warranty Reserves [Member]	'	'	'
Valuation and Qualifying Accounts Disclosure [Line Items]	'	'	'
Balance at beginning of year	359	384	375
Amounts charged to expenses	874	867	1,074
Adjustments to pre-existing warranty reserve	0	0	0
Settlement of warranty	-909	-892	-1,065
Balance at end of year	324	359	384
Valuation Allowance [Member]	'	'	'
Valuation and Qualifying Accounts Disclosure [Line Items]	'	'	'
Balance at beginning of year	1,378	0	'
Amounts charged to expenses	910	1,378	'
Deductions and adjustments	0	0	'
Balance at end of year	$2,288	$1,378	'