CMC Materials (CCMP) 10-Q 7 Aug 17 2017 Q3 Quarterly report Financial data

Document and Entity Information

Document and Entity Information - shares	9 Months Ended
	Jun. 30, 2017	Jul. 31, 2017
Document and Entity Information [Abstract]
Entity Registrant Name	CABOT MICROELECTRONICS CORP
Entity Central Index Key	1,102,934
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 Common Stock, Shares Outstanding		25,306,097
Document Fiscal Year Focus	2,017
Document Fiscal Period Focus	Q3
Document Type	10-Q
Amendment Flag	false
Document Period End Date	Jun. 30, 2017

UNAUDITED CONSOLIDATED STATEMEN

UNAUDITED CONSOLIDATED STATEMENTS OF INCOME - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
UNAUDITED CONSOLIDATED STATEMENTS OF INCOME [Abstract]
Revenue	$ 127,957	$ 108,152	$ 370,395	$ 307,765
Cost of goods sold	65,414	56,127	186,316	158,649
Gross profit	62,543	52,025	184,079	149,116
Operating expenses:
Research, development and technical	14,333	12,928	41,819	42,690
Selling and marketing	7,346	6,243	22,166	19,660
General and administrative	13,953	10,738	41,148	37,991
Total operating expenses	35,632	29,909	105,133	100,341
Operating income	26,911	22,116	78,946	48,775
Interest expense	1,117	1,178	3,402	3,536
Other income (expense), net	(115)	(246)	1,115	396
Income before income taxes	25,679	20,692	76,659	45,635
Provision for income taxes	5,740	1,990	16,209	6,493
Net income	$ 19,939	$ 18,702	$ 60,450	$ 39,142
Basic earnings per share (in dollars per share)	$ 0.79	$ 0.78	$ 2.42	$ 1.62
Weighted average basic shares outstanding (in shares)	25,228,468	23,928,512	24,941,190	24,022,809
Diluted earnings per share (in dollars per share)	$ 0.77	$ 0.76	$ 2.37	$ 1.59
Weighted average diluted shares outstanding (in shares)	25,720,715	24,325,166	25,449,507	24,402,880
Dividends per share (in dollars per share)	$ 0.20	$ 0.18	$ 0.58	$ 0.36

UNAUDITED CONSOLIDATED STATEME3

UNAUDITED CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
UNAUDITED CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME [Abstract]
Net income	$ 19,939	$ 18,702	$ 60,450	$ 39,142
Other comprehensive income (loss), net of tax:
Foreign currency translation adjustments	(2,635)	3,795	(6,326)	10,152
Minimum pension liability adjustment	0	0	0	287
Net unrealized gain (loss) on cash flow hedges	1	(173)	819	(265)
Other comprehensive income (loss), net of tax	(2,634)	3,622	(5,507)	10,174
Comprehensive income	$ 17,305	$ 22,324	$ 54,943	$ 49,316

UNAUDITED CONSOLIDATED BALANCE

UNAUDITED CONSOLIDATED BALANCE SHEETS - USD ($) $ in Thousands	Jun. 30, 2017	Sep. 30, 2016
Current assets:
Cash and cash equivalents	$ 363,902	$ 287,479
Accounts receivable, less allowance for doubtful accounts of $1,799 at June 30, 2017, and $1,828 at September 30, 2016	66,338	62,830
Inventories	70,759	72,123
Prepaid expenses and other current assets	16,803	14,398
Total current assets	517,802	436,830
Property, plant and equipment, net	106,162	106,496
Goodwill	101,812	100,639
Other intangible assets, net	44,643	50,476
Deferred income taxes	19,528	20,747
Other long-term assets	11,327	12,042
Total assets	801,274	727,230
Current liabilities:
Accounts payable	15,958	16,834
Accrued expenses, income taxes payable and other current liabilities	49,295	41,395
Current portion of long-term debt	9,844	7,656
Total current liabilities	75,097	65,885
Long-term debt, net of current portion, less prepaid debt issuance cost of $504 at June 30, 2017 and $696 at September 30, 2016	137,309	146,961
Deferred income taxes	64	75
Other long-term liabilities	13,782	16,661
Total liabilities	226,252	229,582
Commitments and contingencies (Note 10)
Stockholders' equity:
Common Stock: Authorized: 200,000,000 shares, $0.001 par value; Issued: 35,144,183 shares at June 30, 2017, and 34,261,304 shares at September 30, 2016	35	34
Capital in excess of par value of common stock	573,895	530,840
Retained earnings	376,483	330,776
Accumulated other comprehensive income	4,049	9,556
Treasury stock at cost, 9,835,419 shares at June 30, 2017, and 9,744,642 shares at September 30, 2016	(379,440)	(373,558)
Total stockholders' equity	575,022	497,648
Total liabilities and stockholders' equity	$ 801,274	$ 727,230

UNAUDITED CONSOLIDATED BALANCE5

UNAUDITED CONSOLIDATED BALANCE SHEETS (Parenthetical) - USD ($) $ in Thousands	Jun. 30, 2017	Sep. 30, 2016
Current assets
Allowance for doubtful accounts	$ 1,799	$ 1,828
LIABILITIES AND STOCKHOLDERS' EQUITY
Long-term debt, prepaid debt issuance cost	$ 504	$ 696
Stockholders' equity
Common stock: authorized (in shares)	200,000,000	200,000,000
Common stock: par value (in dollars per share)	$ 0.001	$ 0.001
Common stock: issued (in shares)	35,144,183	34,261,304
Treasury stock at cost, shares (in shares)	9,835,419	9,744,642

UNAUDITED CONSOLIDATED STATEME6

UNAUDITED CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	9 Months Ended
	Jun. 30, 2017	Jun. 30, 2016
Cash flows from operating activities:
Net income	$ 60,450	$ 39,142
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	19,530	19,090
Provision for doubtful accounts	25	10
Share-based compensation expense	9,716	11,029
Deferred income tax expense	2,081	516
Non-cash foreign exchange (gain)/loss	470	(539)
(Gain) loss on disposal of property, plant and equipment	(621)	107
Impairment of assets	860	79
Other	(323)	657
Changes in operating assets and liabilities, excluding amounts related to acquisition:
Accounts receivable	(5,638)	(1,110)
Inventories	(247)	655
Prepaid expenses and other assets	(3,405)	(144)
Accounts payable	(1,186)	(2,945)
Accrued expenses, income taxes payable and other liabilities	8,304	(8,790)
Net cash provided by operating activities	90,016	57,757
Cash flows from investing activities:
Additions to property, plant and equipment	(15,901)	(13,836)
Proceeds from the sale of property, plant and equipment	637	17
Acquisition of business, net of cash acquired	0	(126,976)
Proceeds from the sale of investments	175	200
Net cash used in investing activities	(15,089)	(140,595)
Cash flows from financing activities:
Repayment of long-term debt	(7,656)	(6,563)
Repurchases of common stock	(5,882)	(27,855)
Net proceeds from issuance of stock	27,561	5,646
Dividends paid	(13,977)	(4,326)
Tax benefits associated with share-based compensation expense	5,826	770
Net cash provided by (used in) financing activities	5,872	(32,328)
Effect of exchange rate changes on cash	(4,376)	4,063
Increase (decrease) in cash and cash equivalents	76,423	(111,103)
Cash and cash equivalents at beginning of period	287,479	354,190
Cash and cash equivalents at end of period	363,902	243,087
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 the period	$ 2,018	$ 701

BACKGROUND AND BASIS OF PRESENT

BACKGROUND AND BASIS OF PRESENTATION	9 Months Ended
	Jun. 30, 2017
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 helping to enable 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 develop, manufacture and sell CMP polishing pads, which are used in conjunction with slurries in the CMP process. We also develop and provide products for demanding surface modification applications in other industries through our Engineered Surface Finishes (ESF) business. For additional information, refer to Part 1, Item 1, "Business", in our Annual Report on Form 10-K for the fiscal year ended September 30, 2016. The unaudited consolidated financial statements have been prepared by Cabot Microelectronics pursuant to the rules of the Securities and Exchange Commission (SEC) and accounting principles generally accepted in the United States of America (U.S. GAAP). In the opinion of management, these unaudited consolidated financial statements include all adjustments, consisting of normal recurring adjustments, necessary for the fair statement of Cabot Microelectronics' financial position as of June 30, 2017, cash flows for the nine months ended June 30, 2017, and June 30, 2016, and results of operations for the three and nine months ended June 30, 2017, and June 30, 2016. The consolidated balance sheet as of September 30, 2016 was derived from audited financial statements, but does not contain all of the footnote disclosures from the annual financial statements. The results of operations for the three and nine months ended June 30, 2017 may not be indicative of results to be expected for future periods, including the fiscal year ending September 30, 2017. These unaudited consolidated financial statements should be read in conjunction with the consolidated financial statements and related notes thereto included in Cabot Microelectronics' Annual Report on Form 10-K for the fiscal year ended September 30, 2016. 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 June 30, 2017 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 challenging and subjective judgments include, but are not limited to, those estimates related to bad debt expense, inventory valuation, valuation and classification of auction rate securities, impairment of long-lived assets and investments, business combinations, goodwill, other intangible assets, interest rate swaps, 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. 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. Amounts charged to bad debt 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 foreign exchange fluctuations. Uncollectible account balances are charged against the allowance when we believe that it is probable that the receivable will not be recovered. At June 30, 2017, our accounts receivable balance with Toshiba Corporation ("Toshiba") represented a U.S. dollar equivalent of $2,682, which equates to 4.0% of our total accounts receivable balance of $66,338, net of allowance for doubtful accounts, and of which no amounts are past due. We continue to monitor the financial condition of Toshiba and its ability to make the required payments due on our receivables. At present, we do not believe it is probable that the receivables from Toshiba are impaired, and accordingly, we have not recorded a related allowance for doubtful accounts .

BUSINESS COMBINATION

BUSINESS COMBINATION	9 Months Ended
	Jun. 30, 2017
BUSINESS COMBINATION [Abstract]
BUSINESS COMBINATION	2. BUSINESS COMBINATION On October 22, 2015, the Company completed the acquisition of 100% of the outstanding stock of NexPlanar Corporation (NexPlanar), a privately held, U.S. based company specializing in the development, manufacture and sale of advanced CMP pad solutions for the semiconductor industry. We acquired NexPlanar to expand our polishing pad portfolio by adding a complementary pad technology and to leverage our global infrastructure to better serve customers on a global basis, including offering performance-advantaged slurry and pad consumable sets. We paid a total of $126,976, including total purchase consideration of $142,237, less cash acquired of $15,261. The purchase consideration includes $142,167 paid at the date of acquisition and In addition, we paid $154 in compensation expense related to certain unvested NexPlanar stock options settled in cash at the acquisition date. The following table summarizes the fair values of assets acquired and liabilities assumed as of the date of acquisition: Total purchase consideration $ 142,237 Cash $ 15,261 Accounts receivable 3,052 Inventories 2,768 Prepaid expenses and other current assets 1,712 Property, plant and equipment 6,901 Intangible assets 55,000 Deferred tax assets 20,509 Other long-term assets 1,458 Accounts payable (1,057 ) Accrued expenses and other current liabilities (1,472 ) Deferred tax liabilities (20,313 ) Total identifiable net assets 83,819 Goodwill 58,418 $ 142,237 The acquisition was accounted for using the acquisition method of accounting. Tangible and identifiable intangible assets acquired and liabilities assumed are recorded at fair value as of the acquisition date. We finalized the purchase price allocation during the fourth quarter of fiscal 2016. We believe that the information we used provides a reasonable basis for estimating the fair values of assets acquired and liabilities assumed. The fair values of identifiable assets and liabilities acquired were developed with the assistance of third party valuation firms. The fair value of acquired property, plant and equipment is valued at its "value-in-use" as there are no known plans to dispose of any assets. The fair value of acquired identifiable intangible assets was determined using the "income approach" on an individual asset basis. The key assumptions used in the calculation of the discounted cash flows include projected revenue, gross margin, operating expenses, and discount rate. The valuations and the underlying assumptions have been deemed reasonable by Company management. There are inherent uncertainties and management judgment required in these determinations. The following table sets forth the components of identifiable intangible assets acquired and their estimated useful lives as of the date of acquisition: Fair Useful Value Life Trade name $ 8,000 7 years Customer relationships 8,000 11 years Developed technology - product family A 32,000 7 years Developed technology - product family B 2,000 9 years In-process technology 5,000 Total intangible assets $ 55,000 The trade name represents the estimated fair value of the brand and name recognition associated with the marketing of NexPlanar's product offerings. Customer relationships represent the estimated fair value of the underlying relationships and agreements with NexPlanar customers. Developed technology represents the estimated fair value of NexPlanar's technology, processes and knowledge regarding its product offerings. In-process technology represents the fair value assigned to technology projects under development as of the acquisition date. The in-process technology assets are capitalized and accounted for as indefinite-lived intangible assets and will be subject to impairment testing until completion or abandonment of the projects. Upon successful completion of each project, we will make a determination of the appropriate useful life and the related amortization will be recorded as an expense over the estimated useful life based on the future expected cash flow stream. In the fourth quarter of fiscal 2016, we recorded impairment expense of $1,000 representing the entire fair value of one of the in-process technology assets as management determined that expected future cash flows were insufficient to support the value of the asset. The intangible assets subject to amortization have a weighted average useful life of 7.7 years and are being amortized on a straight-line basis. The excess of purchase consideration over the fair value of net assets acquired was recorded as goodwill, and is not deductible for income tax purposes. The goodwill is primarily attributable to anticipated revenue growth from the combination of our and NexPlanar pad technologies, expected synergies from the combined operations, and the assembled workforce of NexPlanar. NexPlanar's results of operations have been included in our unaudited consolidated statements of income and comprehensive income from the date of acquisition. The following supplemental pro forma information summarizes the combined results of operations for Cabot Microelectronics and NexPlanar as if the acquisition had occurred on October 1, 2014. Three Months Ended June 30, Nine Months Ended June 30, 2016 2016 Revenue $ 108,152 $ 309,172 Net income 18,412 39,915 Earnings per share - basic 0.76 1.65 Earnings per share - diluted $ 0.75 $ 1.62 The historical financial information has been adjusted to give effect to the pro forma adjustments, which consist of amortization expense associated with intangible assets, and the elimination of interest expense on NexPlanar debt repaid prior to the acquisition. The pro forma amounts for the nine months ended June 30, 2016 exclude the impact of compensation expense related to unvested NexPlanar stock options settled in cash, and the step-up of inventory as these items are assumed to have occurred during the quarter ended December 31, 2014 had the acquisition been completed on October 1, 2014. The pro forma consolidated results are not necessarily indicative of what the consolidated results actually would have been had the acquisition been completed on October 1, 2014. The pro forma consolidated results do not purport to project future results of combined operations, nor do they reflect the expected realization of any revenue or cost synergies associated with the acquisition.

FAIR VALUE OF FINANCIAL INSTRUM

FAIR VALUE OF FINANCIAL INSTRUMENTS	9 Months Ended
	Jun. 30, 2017
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 table presents financial instruments, other than long-term debt, that we measured at fair value on a recurring basis at June 30, 2017 and September 30, 2016. See Note 8 for a detailed discussion of our long-term debt. We have classified the following assets and liabilities 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. June 30, 2017 Level 1 Level 2 Level 3 Total Fair Value Assets: Cash and cash equivalents $ 363,902 $ - $ - $ 363,902 Other long-term investments 1,153 - - 1,153 Derivative financial instruments - 261 - 261 Total assets $ 365,055 $ 261 $ - $ 365,316 Liabilities: Derivative financial instruments - 822 - 822 Total liabilities $ - $ 822 $ - $ 822 September 30, 2016 Level 1 Level 2 Level 3 Total Fair Value Assets: Cash and cash equivalents $ 287,479 $ - $ - $ 287,479 Other long-term investments 1,028 - - 1,028 Derivative financial instruments - 28 - 28 Total assets $ 288,507 $ 28 $ - $ 288,535 Liabilities: Derivative financial instruments - 1,469 - 1,469 Total liabilities $ - $ 1,469 $ - $ 1,469 Our cash and cash equivalents consist of various bank accounts used to support our operations and investments in institutional money-market funds that are traded in active markets. We invest exclusively in AAA- rated, prime institutional money market funds, comprised of high quality, short-term fixed income securities. 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 is a nonqualified plan. Consequently, the Company owns the assets and the related offsetting liability for disbursement until such time as participant makes a qualifying withdrawal. The long-term asset was adjusted to $1,153 in the third quarter of fiscal 2017 to reflect its fair value as of June 30, 2017. Our derivative financial instruments include forward foreign exchange contracts and interest rate swaps. In the first quarter of fiscal 2015, we entered into floating-to-fixed interest rate swap agreements to hedge the variability in LIBOR-based interest payments on a portion of our outstanding variable rate debt. These interest rate swaps represent our primary use of derivative financial instruments. The fair value of our derivative instruments is estimated using standard valuation models using market-based observable inputs over the contractual term, including one-month LIBOR-based yield curves, among others. We consider the risk of nonperformance, including counterparty credit risk, in the calculation of the fair value of derivative financial instruments. See Note 9 of this Form 10-Q for more information on our use of derivative financial instruments.

INVENTORIES

INVENTORIES	9 Months Ended
	Jun. 30, 2017
INVENTORIES [Abstract]
INVENTORIES	4. INVENTORIES Inventories consisted of the following: June 30, 2017 September 30, 2016 Raw materials $ 38,209 $ 45,109 Work in process 6,332 4,668 Finished goods 26,218 22,346 Total $ 70,759 $ 72,123

GOODWILL AND OTHER INTANGIBLE A

GOODWILL AND OTHER INTANGIBLE ASSETS	9 Months Ended
	Jun. 30, 2017
GOODWILL AND OTHER INTANGIBLE ASSETS [Abstract]
GOODWILL AND OTHER INTANGIBLE ASSETS	5. GOODWILL AND OTHER INTANGIBLE ASSETS Goodwill was $101,812 as of June 30, 2017, and $100,639 as of September 30, 2016. The increase in goodwill was due to $1,028 in foreign exchange fluctuations of the New Taiwan dollar and an adjustment of $145 to a deferred tax liability. The components of other intangible assets are as follows: June 30, 2017 September 30, 2016 Gross Carrying Amount Accumulated Amortization Gross Carrying Amount Accumulated Amortization Other intangible assets subject to amortization: Product technology $ 42,278 $ 16,396 $ 42,194 $ 12,718 Acquired patents and licenses 8,270 8,239 8,270 8,155 Trade secrets and know-how 2,550 2,550 2,550 2,550 Customer relationships, distribution rights and other 28,194 14,654 27,900 12,205 Total other intangible assets subject to amortization 81,292 41,839 80,914 35,628 In-process technology 4,000 4,000 Other indefinite-lived intangibles* 1,190 1,190 Total other intangible assets not subject to amortization 5,190 5,190 Total other intangible assets $ 86,482 $ 41,839 $ 86,104 $ 35,628 *Other indefinite-lived intangible assets not subject to amortization consist primarily of trade names. Amortization expense on our intangible assets was $1,935 and $5,860 for the three and nine months ended June 30, 2017, respectively, and was $2,072 and $6,026 for the three and nine months ended and June 30, 2016, respectively. Estimated future amortization expense for the five succeeding fiscal years is as follows: Fiscal Year Estimated Amortization Expense Remainder of 2017 $ 1,934 2018 7,117 2019 6,675 2020 6,670 2021 6,664 Goodwill and indefinite-lived intangible assets are tested for impairment annually in the fourth quarter of the fiscal year 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. An entity has the option to assess the fair value of a reporting unit either using a qualitative analysis ("step zero") or a quantitative analysis ("step one"). Similarly, an entity has the option to use a step zero or a step one approach to determine the recoverability of indefinite-lived intangible assets. In fiscal 2016, we chose to use a step one analysis for both goodwill impairment and for indefinite-lived intangible asset impairment. We completed our annual impairment test during our fourth quarter of fiscal 2016 and recorded $1,000 of impairment expense on one of the in-process technology assets acquired in the NexPlanar acquisition during the fourth quarter of 2016 based on management's expected future cash flows for this asset. There were no indicators of potential impairment during the quarter ended June 30, 2017, so it was not necessary to perform an impairment review for goodwill and indefinite-lived intangible assets during the quarter. There have been no cumulative impairment charges recorded on the goodwill for any of our reporting units.

OTHER LONG-TERM ASSETS

OTHER LONG-TERM ASSETS	9 Months Ended
	Jun. 30, 2017
OTHER LONG-TERM ASSETS [Abstract]
OTHER LONG-TERM ASSETS	6. OTHER LONG-TERM ASSETS Other long-term assets consisted of the following: June 30, 2017 September 30, 2016 Auction rate securities (ARS) $ 5,319 $ 5,494 Other long-term assets 2,505 2,620 Long-term contract asset 2,350 2,900 Other long-term investments 1,153 1,028 Total $ 11,327 $ 12,042 Our ARS investments at June 30, 2017 consisted of two tax exempt municipal debt securities with a total par value of $5,319, both of which have maturities greater than ten years. The fair value of our ARS, determined using level 2 fair value inputs, was $4,877 as of June 30, 2017. We have classified our ARS as held-to-maturity based on our intention and ability to hold the securities until maturity. We believe the gross unrecognized loss of $442 is due to the illiquidity in the ARS market, rather than to credit loss. 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 will continue to monitor our ARS for impairment indicators, which may require us to record an impairment charge that is deemed other-than-temporary. In the third quarter of fiscal 2015, we amended a supply contract with an existing supplier. The amended agreement includes a fee of $4,500, which provides us the option to purchase certain raw materials beyond calendar 2016. This fee was recorded as a long-term asset at its present value and is being amortized into cost of goods sold on a straight-line basis through December 31, 2019, the expiration date of the agreement. See Note 10 for more information regarding this contract. Other long-term assets are comprised of the long-term portion of prepaid unamortized debt costs, related to our Revolving Credit Facility, as well as miscellaneous deposits and prepayments on contracts extending beyond the next 12 months. As discussed in Note 8, we reclassified $435 of prepaid debt costs related to our Term Loan out of other long-term assets as of September 30, 2016, in accordance with the adoption of a new accounting pronouncement. As discussed in Note 3, we recorded a long-term asset and a corresponding long-term liability of $1,153 representing the fair value of our SERP investments as of June 30, 2017.

ACCRUED EXPENSES, INCOME TAXES

ACCRUED EXPENSES, INCOME TAXES PAYABLE AND OTHER CURRENT LIABILITIES	9 Months Ended
	Jun. 30, 2017
ACCRUED EXPENSES, INCOME TAXES PAYABLE AND OTHER CURRENT LIABILITIES [Abstract]
ACCRUED EXPENSES, INCOME TAXES PAYABLE AND OTHER CURRENT LIABILITIES	7. ACCRUED EXPENSES, INCOME TAXES PAYABLE AND OTHER CURRENT LIABILITIES Accrued expenses, income taxes payable and other current liabilities consisted of the following: June 30, 2017 September 30, 2016 Accrued compensation $ 25,677 $ 17,856 Income taxes payable 5,606 7,878 Dividends payable 5,267 4,502 Raw materials received, not yet invoiced 3,731 2,648 Deferred revenue and customer advances 1,264 782 Warranty accrual 249 243 Taxes, other than income taxes 1,583 775 Current portion of long-term contract liability 1,500 1,500 Other accrued expenses 4,418 5,211 Total $ 49,295 $ 41,395

DEBT

DEBT	9 Months Ended
	Jun. 30, 2017
DEBT [Abstract]
DEBT	8. 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 has never been drawn, 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." On June 27, 2014, we entered into an amendment (the "Amendment") to the Credit Agreement, which (i) increased term loan commitments by $17,500 from $157,500 to $175,000, the same level as the original amount under the Credit Agreement at its inception in 2012; (ii) increased the uncommitted accordion feature on the Revolving Credit Facility from $75,000 to $100,000; (iii) extended the expiration date of the Credit Facilities from February 13, 2017 to June 27, 2019; (iv) relaxed the consolidated leverage ratio financial covenant; and (v) revised certain pricing terms and other terms within the Credit Agreement. On June 27, 2014, we drew the $17,500 of increased term loan commitments, bringing the total outstanding commitments under the Term Loan to $175,000. Borrowings under the amended 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 current Applicable Rate for borrowings under the Credit Facilities is 1.50%, as amended, 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. As amended, the fee ranges from 0.20% to 0.30%, 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 also pay letter of credit fees as necessary. The Term Loan has periodic scheduled repayments; however, 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 certain of our existing and future direct and indirect domestic subsidiaries. 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 certain of its domestic subsidiaries. In the first quarter of fiscal 2017, we adopted the provisions of Accounting Standards Update No. 2015-03, "Simplifying the Presentation of Debt Issuance Costs" (ASU 2015-03) and ASU 2015-15, "Presentation and Subsequent Measurement of Debt Issuance Costs Associated with Line-of-Credit Arrangements". The provisions of ASU 2015-03 require an entity to present the debt issuance costs related to a recognized debt liability in the balance sheet as a direct deduction to the carrying amount of that debt liability. ASU 2015-03 requires adoption on a retrospective basis, wherein the balance sheet of each individual period should be adjusted to reflect the period-specific effects of the guidance. ASU 2015-15 provides guidance on the treatment of debt issuance costs related to line-of-credit arrangements based on comments provided by the SEC staff. The SEC staff stated that it would not object to an entity deferring and presenting debt issuance costs as an asset and subsequently amortizing the deferred debt issuance cost ratably over the term of the line-of-credit arrangement, regardless of whether there are any outstanding borrowings on the line-of-credit arrangement. In accordance with this guidance, we have separated our debt issuance costs between those attributable to our Term Loan and those attributable to our Revolving Credit Facility. The debt issuance costs attributable to our Term Loan are presented as a reduction of the long-term debt balance on our Consolidated Balance Sheet, while the debt issuance costs attributable to our Revolving Credit Facility remain in prepaid expenses and other current assets, and other long-term assets. As of June 30, 2017, $504 of debt issuance costs related to our Term Loan are presented as a reduction of long-term debt. Debt issuance costs related to our Revolving Credit Facility are not material. As of September 30, 2016, we have reclassified $261 and $435 of debt issuance costs related to our Term Loan from prepaid expenses and other current assets, and other long-term assets, respectively, and presented them as a reduction of our long-term debt on our Consolidated Balance Sheet. 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. These include a maximum consolidated leverage ratio of 2.75 to 1.00 and a minimum consolidated fixed charge coverage ratio of 1.25 to 1.00 for the period January 1, 2016 through the expiration of the Credit Agreement. As of June 30, 2017, our consolidated leverage ratio was 0.97 3.47 At June 30, 2017, the fair value of the Term Loan, using level 2 inputs, approximates its carrying value of $147,657 as the loan bears a floating market rate of interest. As of June 30, 2017, $9,844 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 June 30, 2017, scheduled principal repayments of the Term Loan were as follows: Fiscal Year Principal Repayments 2018 14,219 2019 133,438 Total $ 147,657

DERIVATIVE FINANCIAL INSTRUMENT

DERIVATIVE FINANCIAL INSTRUMENTS	9 Months Ended
	Jun. 30, 2017
DERIVATIVE FINANCIAL INSTRUMENTS [Abstract]
DERIVATIVE FINANCIAL INSTRUMENTS	9. DERIVATIVE FINANCIAL INSTRUMENTS We are exposed to various market risks, including risks associated with interest rates and foreign currency exchange rates. We enter into certain derivative transactions to mitigate the volatility associated with these exposures. We have policies in place that define acceptable instrument types we may enter into and we have established controls to limit our market risk exposure. 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 on a gross basis. Cash Flow Hedges – Interest Rate Swap Agreements In the first quarter of fiscal 2015, we entered into floating-to-fixed interest rate swap agreements to hedge the variability in LIBOR-based interest payments on $86,406 of our outstanding variable rate debt. The notional amount of the swaps decreases each quarter by an amount in proportion to our scheduled quarterly principal repayment of debt. The notional value of the swaps was $73,828 as of June 30, 2017, and the swaps are scheduled to expire on June 27, 2019. We have designated these swap agreements as cash flow hedges pursuant to ASC 815, "Derivatives and Hedging". As cash flow hedges, unrealized gains are recognized as assets and unrealized losses are recognized as liabilities. Unrealized gains and losses are designated as effective or ineffective based on a comparison of the changes in fair value of the interest rate swaps and changes in fair value of the underlying exposures being hedged. The effective portion is recorded as a component of accumulated other comprehensive income or loss, while the ineffective portion is recorded as a component of interest expense. Changes in the method by which we pay interest from one-month LIBOR to another rate of interest could create ineffectiveness in the swaps, and result in amounts being reclassified from other comprehensive income into net income. Hedge effectiveness is tested quarterly to determine if hedge treatment continues to be appropriate. Foreign Currency Contracts Not Designated as Hedges 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. As of June 30, 2017 and September 30, 2016, the notional amounts of the forward contracts we held to purchase U.S. dollars in exchange for other international currencies were $6,304 and $8,858, respectively, and the notional amounts of forward contracts we held to sell U.S. dollars in exchange for other international currencies were $20,145 and $15,635, respectively. The fair value of our derivative instruments included in the Consolidated Balance Sheet, which was determined using level 2 inputs, was as follows: Asset Derivatives Liability Derivatives Balance Sheet Location Fair Value at June 30, 2017 Fair Value at September 30, 2016 Fair Value at June 30, 2017 Fair Value at September 30, 2016 Derivatives designated as hedging instruments Interest rate swap contracts Other noncurrent assets $ 152 $ - $ - $ - Accrued expenses and other current liabilities $ - $ - $ 724 $ 612 Other long-term liabilities $ - $ - $ - $ 655 Derivatives not designated as hedging instruments Foreign exchange contracts Prepaid expenses and other current assets $ 109 $ 28 $ - $ - Accrued expenses and other current liabilities $ - $ - $ 98 $ 202 The following table summarizes the effect of our derivative instruments on our Consolidated Statement of Income for the three and nine months ended June 30, 2017 and 2016: Gain (Loss) Recognized in Statement of Income Three Months Ended Nine Months Ended Statement of Income Location June 30, 2017 June 30, 2016 June 30, 2017 June 30, 2016 Derivatives not designated as hedging instruments Foreign exchange contracts Other income (loss), net $ (235 ) $ 440 $ (1,709 ) $ 952 The interest rate swap agreements were deemed to be effective since inception, so there was no impact on our Consolidated Statement of Income. We recorded a $819 unrealized gain in accumulated comprehensive income during the nine months ended June 30, 2017 for these interest rate swaps. During the next 12 months, we expect approximately $98 may be reclassified from accumulated other comprehensive income into interest expense related to our interest rate swaps based on projected rates using the LIBOR forward curve as of June 30, 2017.

COMMITMENTS AND CONTINGENCIES

COMMITMENTS AND CONTINGENCIES	9 Months Ended
	Jun. 30, 2017
COMMITMENTS AND CONTINGENCIES [Abstract]
COMMITMENTS AND CONTINGENCIES	10. 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. Refer to Note 18 of "Notes to the Consolidated Financial Statements" in Item 8 of Part II of our Annual Report on Form 10-K for the fiscal year ended September 30, 2016, for additional information regarding commitments and contingencies. 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 activity during the first nine months of fiscal 2017 was as follows: Balance as of September 30, 2016 $ 243 Reserve for product warranty during the reporting period 389 Settlement of warranty (383 ) Balance as of June 30, 2017 $ 249 POSTRETIREMENT OBLIGATIONS IN FOREIGN JURISDICTIONS We have defined benefit plans covering employees in certain foreign jurisdictions as required by local law, which are unfunded. Benefit costs, consisting primarily of service costs, are recorded as fringe benefit expense under cost of goods sold and operating expenses in our Consolidated Statements of Income. The projected benefit obligations and accumulated benefit obligations under all such unfunded plans are updated annually during the fourth quarter of the fiscal year. Benefit payments under all such unfunded plans to be paid over the next 10 years are expected to be approximately $3,888. For more information regarding these plans, refer to Note 18 of "Notes to the Consolidated Financial Statements" included in Item 8 of Part II of our Annual Report on Form 10-K for the fiscal year ended September 30, 2016. 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. We have a fumed silica supply agreement with Cabot Corporation, which is not a related party and has not been one since 2002, the current term of which runs through December 31, 2019. It provides us the option to purchase fumed silica for the remaining term of the agreement beyond calendar year 2016, for which we will pay a fee of $1,500 in each of calendar years 2017, 2018 and 2019, of which the 2017 payment has already been made. The present value of the remaining fees was $2,920 as of June 30, 2017. The 2018 payment of $1,500 is included in accrued expenses and the remaining $1,420 is included in other long-term liabilities on our Consolidated Balance Sheet. As of June 30, 2017, purchase obligations include $ 9,631 CONTINGENCIES Our subsidiary in South Korea was under an audit in the normal course of business by the Korean customs authority for the period from fiscal years 2011 through 2016. We recorded an assessment in cost of goods sold during the third quarter of fiscal 2017, which was not material to our financial statements. Subsequent to June 30, 2017, but prior to the issuance of our financial statements, we paid the assessment and received notice that this matter was closed.

ACCUMULATED OTHER COMPREHENSIVE

ACCUMULATED OTHER COMPREHENSIVE INCOME (LOSS)	9 Months Ended
	Jun. 30, 2017
ACCUMULATED OTHER COMPREHENSIVE INCOME (LOSS) [Abstract]
ACCUMULATED OTHER COMPREHENSIVE INCOME (LOSS)	11. ACCUMULATED OTHER COMPREHENSIVE INCOME (LOSS) The components of accumulated other comprehensive income (AOCI), including the reclassification adjustments for items that are reclassified from AOCI to net income, are shown below: Foreign Currency Translation Cash Flow Hedges Pension and Other Postretirement Liabilities Total Balance at September 30, 2016 $ 11,985 $ (817 ) $ (1,612 ) $ 9,556 Foreign currency translation adjustment, net of tax of $(1,814) (6,326 ) - - (6,326 ) Unrealized gain (loss) on cash flow hedges: Change in fair value, net of tax of $610 - 1,088 - 1,088 Reclassification adjustment into earnings, net of tax of $(150) - (269 ) - (269 ) Balance at June 30, 2017 $ 5,659 $ 2 $ (1,612 ) $ 4,049 Foreign Currency Translation Cash Flow Hedges Pension and Other Postretirement Liabilities Total Balance at September 30, 2015 $ (4,011 ) $ (901 ) $ (1,178 ) $ (6,090 ) Foreign currency translation adjustment, net of tax of $1,613 10,152 - - 10,152 Unrealized gain (loss) on cash flow hedges: Change in fair value, net of tax of $(90) - (164 ) - (164 ) Reclassification adjustment into earnings, net of tax of $(56) - (101 ) - (101 ) Change in pension and other postretirement liabilities, net of tax of $287 - - 287 287 Balance at June 30, 2016 $ 6,141 $ (1,166 ) $ (891 ) $ 4,084 The before tax amounts reclassified from OCI to net income during the nine months ended June 30, 2017 and 2016, related to our cash flow hedges, were recorded as interest expense on our Consolidated Statement of Income. For the nine month ended June 30, 2017, we recorded $6,326 in currency translation losses, net of tax, that are included in other comprehensive income, primarily due to exchange rate fluctuations in the Japanese yen and Korean won versus the U.S. dollar. These losses primarily relate to changes in the U.S. dollar value of assets and liabilities denominated in local currencies when these asset and liability amounts are translated at month-end exchange rates.

SHARE-BASED COMPENSATION PLANS

SHARE-BASED COMPENSATION PLANS	9 Months Ended
	Jun. 30, 2017
SHARE-BASED COMPENSATION PLANS [Abstract]
SHARE-BASED COMPENSATION PLANS	12. SHARE-BASED COMPENSATION PLANS We issue share-based awards under the following programs: our Cabot Microelectronics Corporation 2012 Omnibus Incentive Plan, as amended effective March 7, 2017 (OIP); our Cabot Microelectronics Corporation 2007 Employee Stock Purchase Plan, as Amended and Restated January 1, 2010 (ESPP); and, pursuant to the OIP, our Directors' Deferred Compensation Plan, as amended September 23, 2008 (DDCP), and our 2001 Executive Officer Deposit Share Program (DSP). In March 2017, our stockholders reapproved the material terms of performance-based awards under the OIP for purposes of complying with Section 162(m) of the Internal Revenue Code of 1986, as amended. Prior to March 2012, when our stockholders first approved the OIP, we issued share-based payments under our Second Amended and Restated Cabot Microelectronics Corporation 2000 Equity Incentive Plan, as amended and restated September 23, 2008 (EIP); our ESPP, and, pursuant to the EIP, the DDCP and DSP. For additional information regarding these programs, refer to Note 13 of "Notes to the Consolidated Financial Statements" included in Item 8 of Part II of our Annual Report on Form 10-K for the fiscal year ended September 30, 2016. Other than the ESPP, all share-based payments granted beginning March 6, 2012 are made from the OIP, and since then, the EIP no longer has been available for any awards. 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, expected dividend yield 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 expected dividend yield represents our annualized dividend in dollars divided by the stock price on the date of grant. The risk-free interest rate is derived from the U.S. Treasury yield curve in effect at the time of grant. Share-based compensation expense for the three and nine months ended June 30, 2017, and 2016, was as follows: Three Months Ended June 30, Nine Months Ended June 30, 2017 2016 2017 2016 Cost of goods sold $ 577 $ 521 $ 1,670 $ 1,590 Research, development and technical 444 392 1,322 1,226 Selling and marketing 346 412 1,032 1,227 General and administrative 1,884 1,051 5,692 7,140 Total share-based compensation expense 3,251 2,376 9,716 11,183 Tax benefit (1,052 ) (385 ) (3,219 ) (3,373 ) Total share-based compensation expense, net of tax $ 2,199 $ 1,991 $ 6,497 $ 7,810 In conjunction with our acquisition of NexPlanar in October 2015, share-based compensation expense for the three months ended December 31, 2015, included $605 related to certain unvested NexPlanar incentive stock options (ISOs) settled in cash at the acquisition date, of which $451 was reversed in the third quarter of fiscal 2016. We also substituted certain NexPlanar ISOs with Cabot Microelectronics Corporation ISOs, preserving the intrinsic value, including the original vesting periods, of the original awards. We accelerated the vesting on the substitute awards made to certain individuals based on the terms of their employment agreements with NexPlanar, and recorded $492 of share-based compensation expense related to this acceleration. The total $1,097 of acquisition-related compensation is included in the table above as general and administrative expense for the nine months ended June 30, 2016. For additional information regarding the estimation of fair value, refer to Note 13 of "Notes to the Consolidated Financial Statements" included in Item 8 of Part II of our Annual Report on Form 10-K for the fiscal year ended September 30, 2016.

OTHER INCOME, NET

OTHER INCOME, NET	9 Months Ended
	Jun. 30, 2017
OTHER INCOME, NET [Abstract]
OTHER INCOME (EXPENSE), NET	13. OTHER INCOME (EXPENSE), NET Other income (expense), net, consisted of the following: Three Months Ended June 30, Nine Months Ended June 30, 2017 2016 2017 2016 Interest income $ 659 $ 267 $ 1,596 $ 654 Other income (expense) (774 ) (513 ) (481 ) (258 ) Total other income (expense), net $ (115 ) $ (246 ) $ 1,115 $ 396 Other income (expense) primarily represents gains and losses recorded on transactions denominated in foreign currencies. The increase in other income was primarily due to the impact of foreign currency fluctuations on monetary assets and liabilities denominated in currencies other than the functional currency, net of the gains and losses incurred on forward foreign exchange contracts discussed in Note 9.

INCOME TAXES

INCOME TAXES	9 Months Ended
	Jun. 30, 2017
INCOME TAXES [Abstract]
INCOME TAXES	14. INCOME TAXES Our effective income tax rate was 22.4% and 21.1% for the three and nine months ended June 30, 2017, respectively, compared to a 9.6% and 14.2% effective income tax rate for the three and nine months ended June 30, 2016. The increase in the effective tax rate during the first nine months of fiscal 2017 was primarily due to changes in the jurisdictional mix of income, and the absence of the retroactive reinstatement of the research and experimentation tax credit in December 2015, and the benefit of $0.9 million in domestic production deductions recorded in fiscal 2016. The Company is currently operating under a tax holiday in South Korea in conjunction with our investment in research, development and manufacturing facilities there. This arrangement allows for a tax at 50% of the local statutory rate in effect for fiscal years 2016 and 2017, following a 0% tax rate in fiscal years 2013, 2014 and 2015. This tax holiday reduced our income tax provision by approximately $3,094 and $2,717 in the first nine months of fiscal 2017 and 2016, respectively. This tax holiday increased our diluted earnings per share by approximately $0.12 and $0.11 during the nine month ended June 30, 2017 and 2016, respectively.

EARNINGS PER SHARE

EARNINGS PER SHARE	9 Months Ended
	Jun. 30, 2017
EARNINGS PER SHARE [Abstract]
EARNINGS PER SHARE	15. 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 that have 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: Three Months Ended June 30, Nine Months Ended June 30, 2017 2016 2017 2016 Numerator: Net Income $ 19,939 $ 18,702 $ 60,450 39,142 Less: income attributable to participating securities (52 ) (110 ) (191 ) (260 ) Earnings available to common shares $ 19,887 $ 18,592 $ 60,259 38,882 Denominator: Weighted average common shares 25,228,468 23,928,512 24,941,190 24,022,809 (Denominator for basic calculation) Weighted average effect of dilutive securities: Share-based compensation 492,247 396,654 508,317 380,071 Diluted weighted average common shares 25,720,715 24,325,166 25,449,507 24,402,880 (Denominator for diluted calculation) Earnings per share: Basic $ 0.79 $ 0.78 $ 2.42 1.62 Diluted $ 0.77 $ 0.76 $ 2.37 1.59 For the three months ended June 30, 2017 and 2016, approximately 0.1 million and 1.2 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. For the nine months ended June 30, 2017 and 2016, approximately 0.4 million and 1.2 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 INDUST

FINANCIAL INFORMATION BY INDUSTRY SEGMENT AND PRODUCT LINE	9 Months Ended
	Jun. 30, 2017
FINANCIAL INFORMATION BY INDUSTRY SEGMENT AND PRODUCT LINE [Abstract]
FINANCIAL INFORMATION BY INDUSTRY SEGMENT AND PRODUCT LINE	16. FINANCIAL INFORMATION BY INDUSTRY SEGMENT AND PRODUCT LINE We operate predominantly in one reportable segment, as defined under ASC 280 – the development, manufacture, and sale of CMP consumables. Revenue generated by product line for the three and nine months ended June 30, 2017, and 2016, was as follows: Three Months Ended June 30, Nine Months Ended June 30, Revenue: 2017 2016 2017 2016 Tungsten slurries $ 54,731 $ 46,559 $ 161,867 $ 134,856 Dielectric slurries 30,266 25,348 87,391 72,045 Polishing pads 17,599 16,048 50,947 46,586 Other Metals slurries 16,090 14,065 46,540 36,517 Engineered Surface Finishes 7,806 4,382 18,866 12,077 Data storage slurries 1,465 1,750 4,784 5,684 Total revenue $ 127,957 $ 108,152 $ 370,395 $ 307,765

NEW ACCOUNTING PRONOUNCEMENTS

NEW ACCOUNTING PRONOUNCEMENTS	9 Months Ended
	Jun. 30, 2017
NEW ACCOUNTING PRONOUNCEMENTS [Abstract]
NEW ACCOUNTING PRONOUNCEMENTS	17. NEW ACCOUNTING PRONOUNCEMENTS In May 2014, the FASB issued ASU No. 2014-09, "Revenue from Contracts with Customers" (Topic 606), an updated standard on revenue recognition . In February 2015, the FASB issued ASU No. 2015-02, "Amendments to the Consolidation Analysis" (Topic 810) . In July 2015, the FASB issued ASU No, 2015-11, "Simplifying the Measurement of Inventory" (Topic 330). The provisions of ASU 2015-11 require an entity to measure inventory at the lower of cost and net realizable value. Net realizable value is the estimated selling price in the ordinary course of business, less reasonably predictable costs of completion, disposal, and transportation. ASU 2015-11 will be effective for us beginning October 1, 2017, but early adoption is permitted. We do not believe the adoption of this standard will have a material effect on our financial statements. In January 2016, the FASB issued ASU No. 2016-01, "Recognition and Measurement of Financial Assets and Financial Liabilities" (Subtopic 825-10). The provision of ASU 2016-01 requires equity investments, other than those accounted for under the equity method of accounting or those that result in consolidation, to be measured at fair value with changes in fair value recognized in net income. ASU 2016-01 simplifies the impairment assessment of equity securities by permitting a qualitative assessment each reporting period, and makes changes to presentation and disclosure of certain classes of financial assets and liabilities. ASU 2016-01 will be effective for us beginning October 1, 2018, but early adoption is permitted. We are currently evaluating the impact of implementation of this standard on our financial statements. In February 2016, the FASB issued ASU No. 2016-02, "Leases" (Topic 842). The provisions of ASU 2016-02 require a dual approach for lessee accounting under which a lessee would recognize a right-of-use asset and a corresponding lease liability. Leases will be classified as either finance or operating leases. For finance leases, a lessee will recognize interest expense and amortization of the right-of-use asset, and for operating leases, the lessee will recognize a straight-line total lease expense. The guidance also requires qualitative and specific quantitative disclosures to supplement the amounts recorded in the financial statements, to afford better understanding of an entity's leasing activities, including any significant judgments and estimates. ASU 2016-02 will be effective for us beginning October 1, 2019, but early adoption is permitted. We are currently evaluating the impact of implementation of this standard on our financial statements. In March 2016, the FASB issued ASU No. 2016-05, "Effect of Derivative Contract Novations on Existing Hedge Accounting Relationships" (Topic 815). The provisions of ASU 2016-05 provide clarification that a change in a counterparty of a derivative instrument that has been designated as a hedging instrument does not require dedesignation of that hedging relationship, provided that all other hedge accounting criteria is met. ASU 2016-05 will be effective for us beginning October 1, 2017, but early adoption is permitted. We do not believe the adoption of this standard will have a material effect on our financial statements. In March 2016, the FASB issued ASU No. 2016-09, "Improvements to Employee Share Based Payment Accounting" (Topic 718). The provisions of this standard involve several aspects of the accounting for share-based payments transactions, including income tax consequences, classification of awards as either equity or liabilities, and classification on the statement of cash flows. ASU 2016-09 will be effective for us beginning October 1, 2017, but early adoption is permitted. We are currently evaluating the impact of implementation of this standard on our financial statements. In June 2016, the FASB issued ASU No. 2016-13, "Measurement of Credit Losses on Financial Instruments" (Topic 326). The provisions of this standard require financial assets measured at amortized cost to be presented at the net amount expected to be collected. An allowance account would be established to present the net carrying value at the amount expect to be collected. ASU 2016-13 also provides that credit losses relating to available-for-sale debt securities should be recorded through an allowance for credit losses. ASU 2016-13 will be effective for us beginning October 1, 2020, but early adoption is permitted as of October 1, 2019. We are currently evaluating the impact of implementation of this standard on our financial statements. In October 2016, the FASB issued ASU No. 2016-16 "Intra-Entity Transfers of Assets Other Than Inventory" (Topic 740). The provisions of this standard provide guidance on recognition of taxes related to intra-entity transfer of assets other than inventory when the transfer occurs. ASU 2016-16 will be effective for us beginning October 1, 2018, but early adoption is permitted. We are currently evaluating the impact of implementation of this standard on our financial statements. In October 2016, the FASB issued ASU No. 2016-17 "Interest Held through Related Parties That Are under Common Control" (Topic 810). The provisions of this standard provide further guidance related to ASU 2015-02, and also provide guidance on consolidation in relation to VIEs and related parties. ASU 2016-17 will be effective for us beginning October 1, 2017, but early adoption is permitted. We do not believe the adoption of this standard will have a material effect on our financial statements as we currently have no interest in any entities that may be considered VIE. In January 2017, the FASB issued ASU No. 2017-01 "Clarifying the Definition of a Business" (Topic 805). The provisions of this standard provide guidance to determine whether the acquisition or sale of a set of assets or activities constitutes a business. The standard requires that an integrated set of assets and activities include an input and a substantive process that together contribute to the ability to create output. ASU 2017-01 will be effective for us beginning October 1, 2017, and early adoption is permitted under specified conditions. We are currently evaluating the impact of implementation of this standard on our financial statements. In January 2017, the FASB issued ASU No. 2017-04 "Simplifying the Test for Goodwill Impairment" (Topic 350). The provisions of this standard eliminate Step 2 from the goodwill impairment test, which required an entity to determine the fair value of its assets and liabilities at the impairment testing date of its goodwill and compare it to its carrying amount to determine a possible impairment loss. Goodwill impairment testing will now be done by comparing the fair value of a reporting unit and its carrying amount. ASU 2017-04 will be effective for us beginning October 1, 2020, but early adoption is permitted as of October 1, 2017. We are currently evaluating the impact of implementation of this standard on our financial statements. In March 2017, the FASB issued ASU No. 2017-07 "Improving the Presentation of Net Period Pension Cost and net Period Postretirement Benefit Cost" (Topic 715). The provisions of ASU 2017-07 provided specific guidance on the presentation of the components of net benefit cost. ASU 2017-07 will be effective for us beginning October 1, 2018. We are currently evaluating the impact of implementation of this standard on our financial statements. In May 2017, the FASB issued ASU No. 2017-09 "Scope of Modification Accounting" (Topic 718). The provisions of ASU 2017-09 provide specific guidance about which changes to the term or conditions of a share-based payment require an entity to apply modification accounting. ASU 2017-09 will be effective for us beginning October 1, 2018. We are currently evaluating the impact of implementation of this standard on our financial statements.

BACKGROUND AND BASIS OF PRESE24

BACKGROUND AND BASIS OF PRESENTATION (Policies)	9 Months Ended
	Jun. 30, 2017
BACKGROUND AND BASIS OF PRESENTATION [Abstract]
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 challenging and subjective judgments include, but are not limited to, those estimates related to bad debt expense, inventory valuation, valuation and classification of auction rate securities, impairment of long-lived assets and investments, business combinations, goodwill, other intangible assets, interest rate swaps, 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.
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. Amounts charged to bad debt 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 foreign exchange fluctuations. Uncollectible account balances are charged against the allowance when we believe that it is probable that the receivable will not be recovered. At June 30, 2017, our accounts receivable balance with Toshiba Corporation ("Toshiba") represented a U.S. dollar equivalent of $2,682, which equates to 4.0% of our total accounts receivable balance of $66,338, net of allowance for doubtful accounts, and of which no amounts are past due. We continue to monitor the financial condition of Toshiba and its ability to make the required payments due on our receivables. At present, we do not believe it is probable that the receivables from Toshiba are impaired, and accordingly, we have not recorded a related allowance for doubtful accounts .

BUSINESS COMBINATION (Tables)

BUSINESS COMBINATION (Tables)	9 Months Ended
	Jun. 30, 2017
BUSINESS COMBINATION [Abstract]
Assets Acquired and Liabilities Assumed	The following table summarizes the fair values of assets acquired and liabilities assumed as of the date of acquisition: Total purchase consideration $ 142,237 Cash $ 15,261 Accounts receivable 3,052 Inventories 2,768 Prepaid expenses and other current assets 1,712 Property, plant and equipment 6,901 Intangible assets 55,000 Deferred tax assets 20,509 Other long-term assets 1,458 Accounts payable (1,057 ) Accrued expenses and other current liabilities (1,472 ) Deferred tax liabilities (20,313 ) Total identifiable net assets 83,819 Goodwill 58,418 $ 142,237
Components of Identifiable Intangible Assets	The following table sets forth the components of identifiable intangible assets acquired and their estimated useful lives as of the date of acquisition: Fair Useful Value Life Trade name $ 8,000 7 years Customer relationships 8,000 11 years Developed technology - product family A 32,000 7 years Developed technology - product family B 2,000 9 years In-process technology 5,000 Total intangible assets $ 55,000
Pro Forma Combined Results of Operations	The following supplemental pro forma information summarizes the combined results of operations for Cabot Microelectronics and NexPlanar as if the acquisition had occurred on October 1, 2014. Three Months Ended June 30, Nine Months Ended June 30, 2016 2016 Revenue $ 108,152 $ 309,172 Net income 18,412 39,915 Earnings per share - basic 0.76 1.65 Earnings per share - diluted $ 0.75 $ 1.62

FAIR VALUE OF FINANCIAL INSTR26

FAIR VALUE OF FINANCIAL INSTRUMENTS (Tables)	9 Months Ended
	Jun. 30, 2017
FAIR VALUE OF FINANCIAL INSTRUMENTS [Abstract]
Fair Value of Financial Instruments	The following table presents financial instruments, other than long-term debt, that we measured at fair value on a recurring basis at June 30, 2017 and September 30, 2016. See Note 8 for a detailed discussion of our long-term debt. We have classified the following assets and liabilities 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. June 30, 2017 Level 1 Level 2 Level 3 Total Fair Value Assets: Cash and cash equivalents $ 363,902 $ - $ - $ 363,902 Other long-term investments 1,153 - - 1,153 Derivative financial instruments - 261 - 261 Total assets $ 365,055 $ 261 $ - $ 365,316 Liabilities: Derivative financial instruments - 822 - 822 Total liabilities $ - $ 822 $ - $ 822 September 30, 2016 Level 1 Level 2 Level 3 Total Fair Value Assets: Cash and cash equivalents $ 287,479 $ - $ - $ 287,479 Other long-term investments 1,028 - - 1,028 Derivative financial instruments - 28 - 28 Total assets $ 288,507 $ 28 $ - $ 288,535 Liabilities: Derivative financial instruments - 1,469 - 1,469 Total liabilities $ - $ 1,469 $ - $ 1,469

INVENTORIES (Tables)

INVENTORIES (Tables)	9 Months Ended
	Jun. 30, 2017
INVENTORIES [Abstract]
Inventories	Inventories consisted of the following: June 30, 2017 September 30, 2016 Raw materials $ 38,209 $ 45,109 Work in process 6,332 4,668 Finished goods 26,218 22,346 Total $ 70,759 $ 72,123

GOODWILL AND OTHER INTANGIBLE28

GOODWILL AND OTHER INTANGIBLE ASSETS (Tables)	9 Months Ended
	Jun. 30, 2017
GOODWILL AND OTHER INTANGIBLE ASSETS [Abstract]
Components of Other Intangible Assets	The components of other intangible assets are as follows: June 30, 2017 September 30, 2016 Gross Carrying Amount Accumulated Amortization Gross Carrying Amount Accumulated Amortization Other intangible assets subject to amortization: Product technology $ 42,278 $ 16,396 $ 42,194 $ 12,718 Acquired patents and licenses 8,270 8,239 8,270 8,155 Trade secrets and know-how 2,550 2,550 2,550 2,550 Customer relationships, distribution rights and other 28,194 14,654 27,900 12,205 Total other intangible assets subject to amortization 81,292 41,839 80,914 35,628 In-process technology 4,000 4,000 Other indefinite-lived intangibles* 1,190 1,190 Total other intangible assets not subject to amortization 5,190 5,190 Total other intangible assets $ 86,482 $ 41,839 $ 86,104 $ 35,628
Estimated Future Amortization Expense for the Succeeding Five Fiscal Years	Amortization expense on our intangible assets was $1,935 and $5,860 for the three and nine months ended June 30, 2017, respectively, and was $2,072 and $6,026 for the three and nine months ended and June 30, 2016, respectively. Estimated future amortization expense for the five succeeding fiscal years is as follows: Fiscal Year Estimated Amortization Expense Remainder of 2017 $ 1,934 2018 7,117 2019 6,675 2020 6,670 2021 6,664

OTHER LONG-TERM ASSETS (Tables)

OTHER LONG-TERM ASSETS (Tables)	9 Months Ended
	Jun. 30, 2017
OTHER LONG-TERM ASSETS [Abstract]
Other Long Term Assets	Other long-term assets consisted of the following: June 30, 2017 September 30, 2016 Auction rate securities (ARS) $ 5,319 $ 5,494 Other long-term assets 2,505 2,620 Long-term contract asset 2,350 2,900 Other long-term investments 1,153 1,028 Total $ 11,327 $ 12,042

ACCRUED EXPENSES, INCOME TAXE30

ACCRUED EXPENSES, INCOME TAXES PAYABLE AND OTHER CURRENT LIABILITIES (Tables)	9 Months Ended
	Jun. 30, 2017
ACCRUED EXPENSES, INCOME TAXES PAYABLE AND OTHER CURRENT LIABILITIES [Abstract]
Accrued Expenses, Income Taxes Payable and Other Current Liabilities	Accrued expenses, income taxes payable and other current liabilities consisted of the following: June 30, 2017 September 30, 2016 Accrued compensation $ 25,677 $ 17,856 Income taxes payable 5,606 7,878 Dividends payable 5,267 4,502 Raw materials received, not yet invoiced 3,731 2,648 Deferred revenue and customer advances 1,264 782 Warranty accrual 249 243 Taxes, other than income taxes 1,583 775 Current portion of long-term contract liability 1,500 1,500 Other accrued expenses 4,418 5,211 Total $ 49,295 $ 41,395

DEBT (Tables)

DEBT (Tables)	9 Months Ended
	Jun. 30, 2017
DEBT [Abstract]
Scheduled Principal Repayments of the Term Loan	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 June 30, 2017, scheduled principal repayments of the Term Loan were as follows: Fiscal Year Principal Repayments 2018 14,219 2019 133,438 Total $ 147,657

DERIVATIVE FINANCIAL INSTRUME32

DERIVATIVE FINANCIAL INSTRUMENTS (Tables)	9 Months Ended
	Jun. 30, 2017
DERIVATIVE FINANCIAL INSTRUMENTS [Abstract]
FV of Derivative Instruments in the Consolidated Balance Sheet	The fair value of our derivative instruments included in the Consolidated Balance Sheet, which was determined using level 2 inputs, was as follows: Asset Derivatives Liability Derivatives Balance Sheet Location Fair Value at June 30, 2017 Fair Value at September 30, 2016 Fair Value at June 30, 2017 Fair Value at September 30, 2016 Derivatives designated as hedging instruments Interest rate swap contracts Other noncurrent assets $ 152 $ - $ - $ - Accrued expenses and other current liabilities $ - $ - $ 724 $ 612 Other long-term liabilities $ - $ - $ - $ 655 Derivatives not designated as hedging instruments Foreign exchange contracts Prepaid expenses and other current assets $ 109 $ 28 $ - $ - Accrued expenses and other current liabilities $ - $ - $ 98 $ 202
Effect of Derivative Instruments on the Consolidated Statement of Income	The following table summarizes the effect of our derivative instruments on our Consolidated Statement of Income for the three and nine months ended June 30, 2017 and 2016: Gain (Loss) Recognized in Statement of Income Three Months Ended Nine Months Ended Statement of Income Location June 30, 2017 June 30, 2016 June 30, 2017 June 30, 2016 Derivatives not designated as hedging instruments Foreign exchange contracts Other income (loss), net $ (235 ) $ 440 $ (1,709 ) $ 952

COMMITMENTS AND CONTINGENCIES (

COMMITMENTS AND CONTINGENCIES (Tables)	9 Months Ended
	Jun. 30, 2017
COMMITMENTS AND CONTINGENCIES [Abstract]
Product Warranty Reserve Activity	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 activity during the first nine months of fiscal 2017 was as follows: Balance as of September 30, 2016 $ 243 Reserve for product warranty during the reporting period 389 Settlement of warranty (383 ) Balance as of June 30, 2017 $ 249

ACCUMULATED OTHER COMPREHENSI34

ACCUMULATED OTHER COMPREHENSIVE INCOME (LOSS) (Tables)	9 Months Ended
	Jun. 30, 2017
ACCUMULATED OTHER COMPREHENSIVE INCOME (LOSS) [Abstract]
Accumulated Other Comprehensive Income (Loss)	The components of accumulated other comprehensive income (AOCI), including the reclassification adjustments for items that are reclassified from AOCI to net income, are shown below: Foreign Currency Translation Cash Flow Hedges Pension and Other Postretirement Liabilities Total Balance at September 30, 2016 $ 11,985 $ (817 ) $ (1,612 ) $ 9,556 Foreign currency translation adjustment, net of tax of $(1,814) (6,326 ) - - (6,326 ) Unrealized gain (loss) on cash flow hedges: Change in fair value, net of tax of $610 - 1,088 - 1,088 Reclassification adjustment into earnings, net of tax of $(150) - (269 ) - (269 ) Balance at June 30, 2017 $ 5,659 $ 2 $ (1,612 ) $ 4,049 Foreign Currency Translation Cash Flow Hedges Pension and Other Postretirement Liabilities Total Balance at September 30, 2015 $ (4,011 ) $ (901 ) $ (1,178 ) $ (6,090 ) Foreign currency translation adjustment, net of tax of $1,613 10,152 - - 10,152 Unrealized gain (loss) on cash flow hedges: Change in fair value, net of tax of $(90) - (164 ) - (164 ) Reclassification adjustment into earnings, net of tax of $(56) - (101 ) - (101 ) Change in pension and other postretirement liabilities, net of tax of $287 - - 287 287 Balance at June 30, 2016 $ 6,141 $ (1,166 ) $ (891 ) $ 4,084

SHARE-BASED COMPENSATION PLANS

SHARE-BASED COMPENSATION PLANS (Tables)	9 Months Ended
	Jun. 30, 2017
SHARE-BASED COMPENSATION PLANS [Abstract]
Share Based Compensation Expense	Share-based compensation expense for the three and nine months ended June 30, 2017, and 2016, was as follows: Three Months Ended June 30, Nine Months Ended June 30, 2017 2016 2017 2016 Cost of goods sold $ 577 $ 521 $ 1,670 $ 1,590 Research, development and technical 444 392 1,322 1,226 Selling and marketing 346 412 1,032 1,227 General and administrative 1,884 1,051 5,692 7,140 Total share-based compensation expense 3,251 2,376 9,716 11,183 Tax benefit (1,052 ) (385 ) (3,219 ) (3,373 ) Total share-based compensation expense, net of tax $ 2,199 $ 1,991 $ 6,497 $ 7,810

OTHER INCOME, NET (Tables)

OTHER INCOME, NET (Tables)	9 Months Ended
	Jun. 30, 2017
OTHER INCOME, NET [Abstract]
Other Income, Net	Other income (expense), net, consisted of the following: Three Months Ended June 30, Nine Months Ended June 30, 2017 2016 2017 2016 Interest income $ 659 $ 267 $ 1,596 $ 654 Other income (expense) (774 ) (513 ) (481 ) (258 ) Total other income (expense), net $ (115 ) $ (246 ) $ 1,115 $ 396

EARNINGS PER SHARE (Tables)

EARNINGS PER SHARE (Tables)	9 Months Ended
	Jun. 30, 2017
EARNINGS PER SHARE [Abstract]
Schedule of Earnings Per Share, Basic and Diluted [Table Text Block]	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: Three Months Ended June 30, Nine Months Ended June 30, 2017 2016 2017 2016 Numerator: Net Income $ 19,939 $ 18,702 $ 60,450 39,142 Less: income attributable to participating securities (52 ) (110 ) (191 ) (260 ) Earnings available to common shares $ 19,887 $ 18,592 $ 60,259 38,882 Denominator: Weighted average common shares 25,228,468 23,928,512 24,941,190 24,022,809 (Denominator for basic calculation) Weighted average effect of dilutive securities: Share-based compensation 492,247 396,654 508,317 380,071 Diluted weighted average common shares 25,720,715 24,325,166 25,449,507 24,402,880 (Denominator for diluted calculation) Earnings per share: Basic $ 0.79 $ 0.78 $ 2.42 1.62 Diluted $ 0.77 $ 0.76 $ 2.37 1.59

FINANCIAL INFORMATION BY INDU38

FINANCIAL INFORMATION BY INDUSTRY SEGMENT AND PRODUCT LINE (Tables)	9 Months Ended
	Jun. 30, 2017
FINANCIAL INFORMATION BY INDUSTRY SEGMENT AND PRODUCT LINE [Abstract]
Revenue Generated by Product Line	Revenue generated by product line for the three and nine months ended June 30, 2017, and 2016, was as follows: Three Months Ended June 30, Nine Months Ended June 30, Revenue: 2017 2016 2017 2016 Tungsten slurries $ 54,731 $ 46,559 $ 161,867 $ 134,856 Dielectric slurries 30,266 25,348 87,391 72,045 Polishing pads 17,599 16,048 50,947 46,586 Other Metals slurries 16,090 14,065 46,540 36,517 Engineered Surface Finishes 7,806 4,382 18,866 12,077 Data storage slurries 1,465 1,750 4,784 5,684 Total revenue $ 127,957 $ 108,152 $ 370,395 $ 307,765

BACKGROUND AND BASIS OF PRESE39

BACKGROUND AND BASIS OF PRESENTATION (Details) $ in Thousands	9 Months Ended
	Jun. 30, 2017USD ($)
Concentration Risk [Line Items]
Accounts receivable, net	$ 66,338
Accounts Receivable [Member] | Credit Concentration Risk [Member] | Toshiba Corporation [Member]
Concentration Risk [Line Items]
Accounts receivable, net	$ 2,682
Concentration risk percentage	4.00%

BUSINESS COMBINATION (Details)

BUSINESS COMBINATION (Details) - USD ($) $ / shares in Units, $ in Thousands	Oct. 22, 2015	Jun. 30, 2017	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Jun. 30, 2017	Jun. 30, 2016	Sep. 30, 2016
Business Acquisition [Line Items]
Acquisition of business, net of cash acquired							$ 0	$ 126,976
Share-based compensation expense							9,716	11,029
Revenue		$ 127,957		$ 108,152			370,395	307,765
Net income (loss)		19,939		18,702			60,450	39,142
Fair values of assets acquired and liabilities assumed [Abstract]
Goodwill		$ 101,812	$ 100,639				$ 101,812		$ 100,639
Impairment expense			1,000
NexPlanar [Member]
Business Acquisition [Line Items]
Business acquisition, percentage of voting interests acquired	100.00%
Acquisition of business, net of cash acquired	$ 126,976
Cash Acquired from Acquisition	15,261
Purchase price	142,167
Purchase price adjustment					$ 70
Share-based compensation expense				(451)		$ 605			$ 154
Fair values of assets acquired and liabilities assumed [Abstract]
Total purchase consideration	142,237
Cash	15,261
Accounts receivable	3,052
Inventories	2,768
Prepaid expenses and other current assets	1,712
Property, plant and equipment	6,901
Intangible assets	55,000
Deferred tax assets	20,509
Other long-term assets	1,458
Accounts payable	(1,057)
Accrued expenses and other current liabilities	(1,472)
Deferred tax liabilities	(20,313)
Total identifiable net assets	83,819
Goodwill	$ 58,418
Impairment expense			$ 1,000
Weighted average useful life	7 years 8 months 12 days
Business acquisition, pro forma information [Abstract]
Revenues				108,152				309,172
Net income				$ 18,412				$ 39,915
Earnings per share - basic (in dollars per share)				$ 0.76				$ 1.65
Earnings per share - diluted (in dollars per share)				$ 0.75				$ 1.62
Acquired Finite-Lived Intangible Assets [Line Items]
Fair value	$ 55,000
NexPlanar [Member] | Trade Name [Member]
Acquired Finite-Lived Intangible Assets [Line Items]
Fair value	$ 8,000
Useful life	7 years
NexPlanar [Member] | Customer Relationships [Member]
Acquired Finite-Lived Intangible Assets [Line Items]
Fair value	$ 8,000
Useful life	11 years
NexPlanar [Member] | Developed Technology - Product Family A [Member]
Acquired Finite-Lived Intangible Assets [Line Items]
Fair value	$ 32,000
Useful life	7 years
NexPlanar [Member] | Developed Technology - Product Family B [Member]
Acquired Finite-Lived Intangible Assets [Line Items]
Fair value	$ 2,000
Useful life	9 years
NexPlanar [Member] | In-process Technology [Member]
Acquired Finite-Lived Intangible Assets [Line Items]
Fair value	$ 5,000

FAIR VALUE OF FINANCIAL INSTR41

FAIR VALUE OF FINANCIAL INSTRUMENTS (Details) - Recurring [Member] - USD ($) $ in Thousands	Jun. 30, 2017	Sep. 30, 2016
Assets [Abstract]
Cash and cash equivalents	$ 363,902	$ 287,479
Other long-term investments	1,153	1,028
Derivative financial instruments	261	28
Total assets	365,316	288,535
Liabilities [Abstract]
Derivative financial instruments	822	1,469
Total liabilities	822	1,469
Level 1 [Member]
Assets [Abstract]
Cash and cash equivalents	363,902	287,479
Other long-term investments	1,153	1,028
Derivative financial instruments	0	0
Total assets	365,055	288,507
Liabilities [Abstract]
Derivative financial instruments	0	0
Total liabilities	0	0
Level 2 [Member]
Assets [Abstract]
Cash and cash equivalents	0	0
Other long-term investments	0	0
Derivative financial instruments	261	28
Total assets	261	28
Liabilities [Abstract]
Derivative financial instruments	822	1,469
Total liabilities	822	1,469
Level 3 [Member]
Assets [Abstract]
Cash and cash equivalents	0	0
Other long-term investments	0	0
Derivative financial instruments	0	0
Total assets	0	0
Liabilities [Abstract]
Derivative financial instruments	0	0
Total liabilities	$ 0	$ 0

INVENTORIES (Details)

INVENTORIES (Details) - USD ($) $ in Thousands	Jun. 30, 2017	Sep. 30, 2016
INVENTORIES [Abstract]
Raw materials	$ 38,209	$ 45,109
Work in process	6,332	4,668
Finished goods	26,218	22,346
Total	$ 70,759	$ 72,123

GOODWILL AND OTHER INTANGIBLE43

GOODWILL AND OTHER INTANGIBLE ASSETS (Details) - USD ($) $ in Thousands		3 Months Ended			9 Months Ended
		Jun. 30, 2017	Sep. 30, 2016	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
GOODWILL AND OTHER INTANGIBLE ASSETS [Abstract]
Goodwill		$ 101,812	$ 100,639		$ 101,812
Goodwill, Other Increase (Decrease)					145
Foreign exchange fluctuation					1,028
Finite-Lived Intangible Assets [Line Items]
Total other intangible assets subject to amortization, gross carrying amount		81,292	80,914		81,292
Accumulated amortization		41,839	35,628		41,839
Indefinite-lived Intangible Assets by Major Class [Line Items]
Total other intangible assets not subject to amortization		5,190	5,190		5,190
Total other intangible assets, gross carrying amount		86,482	86,104		86,482
Other intangible assets [Abstract]
Amortization expense		1,935		$ 2,072	5,860	$ 6,026
Estimated future amortization expense [Abstract]
Remainder of 2017		1,934			1,934
2,018		7,117			7,117
2,019		6,675			6,675
2,020		6,670			6,670
2,021		6,664			6,664
Impairment expense			1,000
In-process Technology [Member]
Indefinite-lived Intangible Assets by Major Class [Line Items]
Total other intangible assets not subject to amortization		4,000	4,000		4,000
Other Indefinite-lived Intangibles [Member]
Indefinite-lived Intangible Assets by Major Class [Line Items]
Total other intangible assets not subject to amortization	[1]	1,190	1,190		1,190
Product Technology [Member]
Finite-Lived Intangible Assets [Line Items]
Total other intangible assets subject to amortization, gross carrying amount		42,278	42,194		42,278
Accumulated amortization		16,396	12,718		16,396
Acquired Patents and Licenses [Member]
Finite-Lived Intangible Assets [Line Items]
Total other intangible assets subject to amortization, gross carrying amount		8,270	8,270		8,270
Accumulated amortization		8,239	8,155		8,239
Trade Secrets and Know-how [Member]
Finite-Lived Intangible Assets [Line Items]
Total other intangible assets subject to amortization, gross carrying amount		2,550	2,550		2,550
Accumulated amortization		2,550	2,550		2,550
Customer Relationships, Distribution Rights and Other
Finite-Lived Intangible Assets [Line Items]
Total other intangible assets subject to amortization, gross carrying amount		28,194	27,900		28,194
Accumulated amortization		$ 14,654	$ 12,205		$ 14,654
[1]	Other indefinite-lived intangible assets not subject to amortization consist primarily of trade names.

OTHER LONG-TERM ASSETS (Details

OTHER LONG-TERM ASSETS (Details) $ in Thousands	9 Months Ended
	Jun. 30, 2017USD ($)Security	Sep. 30, 2016USD ($)	Jun. 30, 2015USD ($)
Other long-term assets [Abstract]
Auction rate securities (ARS)	$ 5,319	$ 5,494
Other long-term assets	2,505	2,620
Long-term contract asset	2,350	2,900
Other long-term investments	1,153	1,028
Total	$ 11,327	12,042
Number of tax exempt municipal debt securities | Security	2
Minimum maturity period of municipal debt securities	10 years
Fair value of auction rate securities	$ 4,877
Gross unrecognized loss of ARS	442
Long-term contract asset face amount			$ 4,500
Long-term liability, SERP investments	$ 1,153
Accounting Standards Update 2015-03 [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Debt issuance costs, noncurrent		$ (435)

ACCRUED EXPENSES, INCOME TAXE45

ACCRUED EXPENSES, INCOME TAXES PAYABLE AND OTHER CURRENT LIABILITIES (Details) - USD ($) $ in Thousands	Jun. 30, 2017	Sep. 30, 2016
ACCRUED EXPENSES, INCOME TAXES PAYABLE AND OTHER CURRENT LIABILITIES [Abstract]
Accrued compensation	$ 25,677	$ 17,856
Income taxes payable	5,606	7,878
Dividends payable	5,267	4,502
Raw materials received, not yet invoiced	3,731	2,648
Deferred revenue and customer advances	1,264	782
Warranty accrual	249	243
Taxes, other than income taxes	1,583	775
Current portion of long-term contract liability	1,500	1,500
Other accrued expenses	4,418	5,211
Total	$ 49,295	$ 41,395

DEBT (Details)

DEBT (Details) - USD ($) $ in Thousands	Jun. 27, 2014	Jun. 26, 2014	Jun. 30, 2017	Sep. 30, 2016	Feb. 13, 2012
Debt Instrument [Line Items]
Discount on Long Term Debt - Prepaid Debt Cost			$ 504	$ 696
Current portion of long-term debt			$ 9,844	7,656
Credit Agreement [Member] | Revolving Credit Facility [Member]
Debt Instrument [Line Items]
Line of credit facility, borrowing capacity		$ 75,000
Maturity date of credit facility		Feb. 13, 2017
Credit Agreement [Member] | Term Loan [Member]
Debt Instrument [Line Items]
Face amount of debt		$ 157,500			$ 175,000
Amended Credit Agreement [Member]
Debt Instrument [Line Items]
Interest rate description			Borrowings under the amended 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 current Applicable Rate for borrowings under the Credit Facilities is 1.50%, as amended, 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.
Covenant terms			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. These include a maximum consolidated leverage ratio of 2.75 to 1.00 and a minimum consolidated fixed charge coverage ratio of 1.25 to 1.00 for the period January 1, 2016 through the expiration of the Credit Agreement. As of June 30, 2017, our consolidated leverage ratio was 0.97 to 1.00 and our consolidated fixed charge coverage ratio was 3.47 to 1.00. The Credit Agreement also contains customary affirmative covenants and events of default. We believe we are in compliance with these covenants.
Consolidated leverage ratio			0.97
Consolidated fixed charge coverage ratio			3.47
Amended Credit Agreement [Member] | Minimum [Member]
Debt Instrument [Line Items]
Consolidated fixed charge coverage ratio			1.25
Amended Credit Agreement [Member] | Maximum [Member]
Debt Instrument [Line Items]
Consolidated leverage ratio			2.75
Amended Credit Agreement [Member] | Federal Funds Rate [Member]
Debt Instrument [Line Items]
Basis spread on variable rate			0.50%
Amended Credit Agreement [Member] | LIBOR [Member]
Debt Instrument [Line Items]
Basis spread on variable rate			1.00%
Current applicable rate			1.50%
Amended Credit Agreement [Member] | Base Rate [Member]
Debt Instrument [Line Items]
Current applicable rate			0.25%
Amended Credit Agreement [Member] | Revolving Credit Facility [Member]
Debt Instrument [Line Items]
Line of credit facility, borrowing capacity			$ 100,000
Maturity date of credit facility			Jun. 27, 2019
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. As amended, the fee ranges from 0.20% to 0.30%, based on our consolidated leverage ratio.
Amended Credit Agreement [Member] | Revolving Credit Facility [Member] | Minimum [Member]
Debt Instrument [Line Items]
Commitment fee percentage			0.20%
Amended Credit Agreement [Member] | Revolving Credit Facility [Member] | Maximum [Member]
Debt Instrument [Line Items]
Commitment fee percentage			0.30%
Amended Credit Agreement [Member] | Term Loan [Member]
Debt Instrument [Line Items]
Increase in loan commitments	$ 17,500
Amount drawn from increase in loan commitments	17,500
Term loan commitments outstanding	$ 175,000
Discount on Long Term Debt - Prepaid Debt Cost			$ 504
Fair value of debt			147,657
Current portion of long-term debt			9,844
Long-term Debt, by Maturity [Abstract]
2,018			14,219
2,019			133,438
Long Term Debt			$ 147,657
ASU 2015-03 [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Debt issuance costs, current				(261)
Debt issuance costs, noncurrent				$ (435)

DERIVATIVE FINANCIAL INSTRUME47

DERIVATIVE FINANCIAL INSTRUMENTS (Details) - USD ($) $ in Thousands	9 Months Ended
	Jun. 30, 2017	Sep. 30, 2016	Dec. 31, 2014
Interest Rate Swap [Member]
Derivative [Line Items]
Outstanding variable rate debt			$ 86,406
Derivative notional amount	$ 73,828
Derivatives expiration date	Jun. 27, 2019
Unrealized gain	$ 819
Reclassified from accumulated other comprehensive income into interest expense	$ 98
Reclassification period	12 months
Foreign Exchange Contract [Member] | Buy [Member]
Derivative [Line Items]
Derivative notional amount	$ 6,304	$ 8,858
Foreign Exchange Contract [Member] | Sell [Member]
Derivative [Line Items]
Derivative notional amount	$ 20,145	$ 15,635

DERIVATIVE FINANCIAL INSTRUME48

DERIVATIVE FINANCIAL INSTRUMENTS, Fair Value of Derivative Instruments in the Consolidated Balance Sheet (Details) - USD ($) $ in Thousands	Jun. 30, 2017	Sep. 30, 2016
Designated as Hedging Instrument [Member] | Interest Rate Swap [Member] | Other Noncurrent Assets [Member]
Derivatives, Fair Value [Line Items]
Fair value of foreign exchange contract asset derivatives	$ 152	$ 0
Fair value of foreign exchange contract liability derivatives	0	0
Designated as Hedging Instrument [Member] | Interest Rate Swap [Member] | 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	724	612
Designated as Hedging Instrument [Member] | Interest Rate Swap [Member] | Other Long-term 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	655
Not Designated as Hedging Instrument [Member] | Foreign Exchange Contract [Member] | 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	98	202
Not Designated as Hedging Instrument [Member] | Foreign Exchange Contract [Member] | Prepaid Expenses and Other Current Assets [Member]
Derivatives, Fair Value [Line Items]
Fair value of foreign exchange contract asset derivatives	109	28
Fair value of foreign exchange contract liability derivatives	$ 0	$ 0

DERIVATIVE FINANCIAL INSTRUME49

DERIVATIVE FINANCIAL INSTRUMENTS, Effect of Derivative Instruments on the Consolidated Statement of Income (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Not Designated as Hedging Instrument [Member] | Foreign Exchange Contract [Member] | Other income (expense), net [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Other income (loss), net	$ (235)	$ 440	$ (1,709)	$ 952

COMMITMENTS AND CONTINGENCIES50

COMMITMENTS AND CONTINGENCIES (Details) - USD ($) $ in Thousands	9 Months Ended
	Jun. 30, 2017	Sep. 30, 2016
Warranty reserve activity [Roll Forward]
Balance as of beginning of period	$ 243
Reserve for product warranty during the reporting period	389
Settlement of warranty	(383)
Balance as of end of period	$ 249
Postretirement Obligations in Foreign Jurisdictions [Abstract]
Expected term for benefit payments of all unfunded plans	10 years
2017 to 2026	$ 3,888
Purchase obligations [Abstract]
Purchase obligation, due in 2017	1,500
Purchase obligation, due in 2018	1,500
Purchase obligation, due in 2019	1,500
Purchase obligation	2,920
Current portion of long-term contract liability	1,500	$ 1,500
Long-term contract liability	1,420
Contractual obligation	$ 9,631

ACCUMULATED OTHER COMPREHENSI51

ACCUMULATED OTHER COMPREHENSIVE INCOME (LOSS) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Components of Accumulated Comprehensive Income (Loss) [Roll Forward]
Balance, beginning of period			$ 497,648
Foreign currency translation adjustments, net of tax	$ (2,635)	$ 3,795	(6,326)	$ 10,152
Change in fair value, net of tax			1,088	(164)
Reclassification adjustment into earnings, net of tax			(269)	(101)
Change in pension and other postretirement liabilities, net of tax of $0	0	0	0	287
Balance, end of period	575,022		575,022
Other Comprehensive Income (Loss), Tax [Abstract]
Foreign currency translation adjustment, tax			(1,814)	1,613
Change in fair value, tax			610	(90)
Reclassification adjustment into earnings, tax			(150)	(56)
Change in pension and other postretirement liabilities, tax			0	287
Accumulated Other Comprehensive Income (Loss) [Member]
Components of Accumulated Comprehensive Income (Loss) [Roll Forward]
Balance, beginning of period			9,556	(6,090)
Balance, end of period	4,049	4,084	4,049	4,084
Foreign Currency Translation Adjustment [Member]
Components of Accumulated Comprehensive Income (Loss) [Roll Forward]
Balance, beginning of period			11,985	(4,011)
Foreign currency translation adjustments, net of tax			(6,326)	10,152
Balance, end of period	5,659	6,141	5,659	6,141
Cash Flow Hedges [Member]
Components of Accumulated Comprehensive Income (Loss) [Roll Forward]
Balance, beginning of period			(817)	(901)
Change in fair value, net of tax			1,088	(164)
Reclassification adjustment into earnings, net of tax			(269)	(101)
Balance, end of period	2	(1,166)	2	(1,166)
Pension and Other Postretirement Liabilities [Member]
Components of Accumulated Comprehensive Income (Loss) [Roll Forward]
Balance, beginning of period			(1,612)	(1,178)
Change in pension and other postretirement liabilities, net of tax of $0				287
Balance, end of period	$ (1,612)	$ (891)	$ (1,612)	$ (891)

SHARE-BASED COMPENSATION PLAN52

SHARE-BASED COMPENSATION PLANS (Details) $ in Thousands	3 Months Ended				9 Months Ended		12 Months Ended
	Jun. 30, 2017USD ($)Director	Mar. 31, 2017USD ($)	Jun. 30, 2016USD ($)	Dec. 31, 2015USD ($)	Jun. 30, 2017USD ($)Director	Jun. 30, 2016USD ($)	Sep. 30, 2016USD ($)
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Total share-based compensation expense	$ 3,251		$ 2,376		$ 9,716	$ 11,183
Tax benefit	(1,052)		(385)		(3,219)	(3,373)
Total share-based compensation expense, net of tax	$ 2,199		1,991		$ 6,497	7,810
Number of non-employee directors who have completed two full terms of service | Director	2				2
Fair value of awards for completing minimum full terms of service		$ 377
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based compensation expense					$ 9,716	11,029
NexPlanar [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based compensation expense			(451)	$ 605			$ 154
Accelerated share-based compensation expense				$ 492
Cost of Goods Sold [Member]
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Total share-based compensation expense	$ 577		521		1,670	1,590
Research, Development and Technical [Member]
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Total share-based compensation expense	444		392		1,322	1,226
Selling and Marketing [Member]
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Total share-based compensation expense	346		412		1,032	1,227
General and Administrative Expense [Member]
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Total share-based compensation expense	$ 1,884		$ 1,051		$ 5,692	7,140
General and Administrative Expense [Member] | NexPlanar [Member]
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Total share-based compensation expense						$ 1,097

OTHER INCOME, NET (Details)

OTHER INCOME, NET (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
OTHER INCOME, NET [Abstract]
Interest income	$ 659	$ 267	$ 1,596	$ 654
Other income (expense)	(774)	(513)	(481)	(258)
Total other income (expense), net	$ (115)	$ (246)	$ 1,115	$ 396

INCOME TAXES (Details)

INCOME TAXES (Details) - USD ($)	3 Months Ended		9 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
INCOME TAXES [Abstract]
Effective income tax rate	22.40%	9.60%	21.10%	14.20%
Tax benefit for additional domestic production deductions				$ 900
Income Tax Holiday [Line Items]
Former tax holiday percentage (in hundredths)	0.00%		0.00%
Tax Holiday approximate diluted earning per share benefit (in dollars per share)			$ 0.12	$ 0.11
Foreign Country [Member] | South Korea [Member]
Income Tax Holiday [Line Items]
Percentage of local statutory rate in effect for 2016	50.00%		50.00%
Percentage of local statutory rate in effect for 2017	50.00%		50.00%
Income tax provision reduction as a result of the tax holiday			$ 3,094,000	$ 2,717,000

EARNINGS PER SHARE (Details)

EARNINGS PER SHARE (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		9 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Numerator [Abstract]
Net income	$ 19,939	$ 18,702	$ 60,450	$ 39,142
Less: income attributable to participating securities	(52)	(110)	(191)	(260)
Earnings available to common shares	$ 19,887	$ 18,592	$ 60,259	$ 38,882
Denominator [Abstract]
Weighted average common shares (Denominator for basic calculation) (in shares)	25,228,468	23,928,512	24,941,190	24,022,809
Weighted average effect of dilutive securities [Abstract]
Share-based compensation (in shares)	492,247	396,654	508,317	380,071
Diluted weighted average common shares (Denominator for diluted calculation) (in shares)	25,720,715	24,325,166	25,449,507	24,402,880
Earnings per share [Abstract]
Basic (in dollars per share)	$ 0.79	$ 0.78	$ 2.42	$ 1.62
Diluted (in dollars per share)	$ 0.77	$ 0.76	$ 2.37	$ 1.59
Stock Options [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Outstanding stock options excluded from diluted earnings (in shares)	100,000	1,200,000	400,000	1,200,000

FINANCIAL INFORMATION BY INDU56

FINANCIAL INFORMATION BY INDUSTRY SEGMENT AND PRODUCT LINE (Details) $ in Thousands	3 Months Ended		9 Months Ended
	Jun. 30, 2017USD ($)	Jun. 30, 2016USD ($)	Jun. 30, 2017USD ($)Segment	Jun. 30, 2016USD ($)
FINANCIAL INFORMATION BY INDUSTRY SEGMENT AND PRODUCT LINE [Abstract]
Number of segments | Segment			1
Revenue from External Customer [Line Items]
Revenue	$ 127,957	$ 108,152	$ 370,395	$ 307,765
Tungsten Slurries [Member]
Revenue from External Customer [Line Items]
Revenue	54,731	46,559	161,867	134,856
Dielectric Slurries [Member]
Revenue from External Customer [Line Items]
Revenue	30,266	25,348	87,391	72,045
Polishing Pads [Member]
Revenue from External Customer [Line Items]
Revenue	17,599	16,048	50,947	46,586
Other Metals Slurries [Member]
Revenue from External Customer [Line Items]
Revenue	16,090	14,065	46,540	36,517
Engineered Surface Finishes [Member]
Revenue from External Customer [Line Items]
Revenue	7,806	4,382	18,866	12,077
Data Storage Slurries [Member]
Revenue from External Customer [Line Items]
Revenue	$ 1,465	$ 1,750	$ 4,784	$ 5,684