TransDigm (TDG) 10-K 19 Nov 19 2019 FY Annual report Financial data

Document and Entity Information

Document and Entity Information - USD ($)	12 Months Ended
	Sep. 30, 2019	Nov. 17, 2019	Mar. 31, 2019
Cover page.
Document Type	10-K
Document Annual Report	true
Document Period End Date	Sep. 30, 2019
Document Transition Report	false
Entity File Number	001-32833
Entity Registrant Name	TransDigm Group Incorporated
Entity Central Index Key	0001260221
Current Fiscal Year End Date	--09-30
Document Fiscal Year Focus	2019
Document Fiscal Period Focus	FY
Amendment Flag	false
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	41-2101738
Entity Address, Address Line One	1301 East 9th Street,
Entity Address, Address Line Two	Suite 3000,
Entity Address, City or Town	Cleveland,
Entity Address, State or Province	OH
Entity Address, Postal Zip Code	44114
City Area Code	216
Local Phone Number	706-2960
Title of 12(b) Security	Common Stock, $0.01 par value
Trading Symbol	TDG
Security Exchange Name	NYSE
Entity Well-known Seasoned Issuer	Yes
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Large Accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Shell Company	false
Entity Public Float			$ 24,193,750,882
Entity Common Stock, Shares Outstanding		53,548,349
Documents Incorporated by Reference	Certain sections of the registrant’s definitive Proxy Statement to be filed in connection with its 2020 Annual Meeting of Shareholders, are incorporated by reference into Part III of this Annual Report on Form 10-K.

Consolidated Balance Sheets

Consolidated Balance Sheets - USD ($) $ in Thousands	Sep. 30, 2019	Sep. 30, 2018
CURRENT ASSETS:
Cash and cash equivalents	$ 1,467,486	$ 2,073,017
Trade accounts receivable—Net	1,067,603	704,310
Inventories—Net	1,232,649	805,292
Assets held-for-sale	962,129	0
Prepaid expenses and other	135,380	74,668
Total current assets	4,865,247	3,657,287
PROPERTY, PLANT AND EQUIPMENT—NET	756,757	388,333
GOODWILL	7,820,103	6,223,290
OTHER INTANGIBLE ASSETS—NET	2,743,820	1,788,404
OTHER	68,804	140,153
TOTAL ASSETS	16,254,731	12,197,467
CURRENT LIABILITIES:
Current portion of long-term debt	80,213	75,817
Short-term borrowings—trade receivable securitization facility	349,519	299,519
Accounts payable	276,590	173,603
Accrued liabilities	675,695	351,443
Liabilities held-for-sale	156,739	0
Total current liabilities	1,538,756	900,382
LONG-TERM DEBT	16,469,221	12,501,946
DEFERRED INCOME TAXES	440,817	399,496
OTHER NON-CURRENT LIABILITIES	691,020	204,114
Total liabilities	19,139,814	14,005,938
TD GROUP STOCKHOLDERS’ DEFICIT:
Common stock—$.01 par value; authorized 224,400,000 shares; issued 57,623,311 and 56,895,686 shares at September 30, 2019 and 2018	576	569
Additional paid-in capital	1,378,760	1,208,742
Accumulated deficit	(3,119,956)	(2,246,578)
Accumulated other comprehensive (loss) income	(378,981)	4,100
Treasury stock, at cost; 4,161,326 shares at September 30, 2019 and 2018	(775,304)	(775,304)
Total TD Group stockholders’ deficit	(2,894,905)	(1,808,471)
NONCONTROLLING INTERESTS	9,822	0
Total stockholders’ deficit	(2,885,083)	(1,808,471)
TOTAL LIABILITIES AND STOCKHOLDERS’ DEFICIT	$ 16,254,731	$ 12,197,467

Consolidated Balance Sheets (Pa

Consolidated Balance Sheets (Parenthetical) - $ / shares	Sep. 30, 2019	Sep. 30, 2018
Statement of Financial Position [Abstract]
Common stock, par value	$ 0.01	$ 0.01
Common stock, shares authorized	224,400,000	224,400,000
Common stock, shares issued	57,623,311	56,895,686
Treasury stock, shares	4,161,326	4,161,326

Consolidated Statements of Inco

Consolidated Statements of Income - USD ($) shares in Thousands, $ in Thousands	12 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2017
NET SALES	$ 5,223,203	$ 3,811,126	$ 3,504,286
COST OF SALES	2,413,932	1,633,616	1,519,659
GROSS PROFIT	2,809,271	2,177,510	1,984,627
SELLING AND ADMINISTRATIVE EXPENSES	747,773	449,676	412,555
AMORTIZATION OF INTANGIBLE ASSETS	134,952	72,454	89,226
INCOME FROM OPERATIONS	1,926,546	1,655,380	1,482,846
INTEREST EXPENSE—Net	859,753	663,008	602,589
REFINANCING COSTS	3,013	6,396	39,807
OTHER EXPENSE—Net	915	419	3,020
INCOME FROM CONTINUING OPERATIONS BEFORE INCOME TAXES	1,062,865	985,557	837,430
INCOME TAX PROVISION	221,986	24,021	208,889
INCOME FROM CONTINUING OPERATIONS INCLUDING NONCONTROLLING INTERESTS	840,879	961,536	628,541
INCOME (LOSS) FROM DISCONTINUED OPERATIONS, NET OF TAX	50,432	(4,474)	(31,654)
Net income including noncontrolling interests	891,311	957,062	596,887
NET INCOME ATTRIBUTABLE TO NONCONTROLLING INTERESTS	(1,541)	0	0
NET INCOME ATTRIBUTABLE TO TD GROUP	889,770	957,062	596,887
NET INCOME APPLICABLE TO TD GROUP COMMON STOCK	$ 778,749	$ 900,914	$ 437,630
Net earnings per share:
Net earnings per share from continuing operations—basic and diluted	$ 12.94	$ 16.28	$ 8.45
Net earnings (loss) per share from discontinued operations—basic and diluted	0.90	(0.08)	(0.57)
Net earnings per share	13.84	16.20	7.88
Cash dividends paid per common share	$ 30	$ 0	$ 46
Weighted-average shares outstanding:
Basic and diluted	56,265	55,597	55,530

Condensed Consolidated Statemen

Condensed Consolidated Statements Of Comprehensive Income - USD ($) $ in Thousands	12 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2017
Net income including noncontrolling interests	$ 891,311	$ 957,062	$ 596,887
NET INCOME ATTRIBUTABLE TO NONCONTROLLING INTERESTS	(1,541)	0	0
NET INCOME ATTRIBUTABLE TO TD GROUP	889,770	957,062	596,887
Other comprehensive income (loss), net of tax:
Foreign currency translation	(114,856)	(10,253)	22,241
Unrealized (loss) gain on derivatives	(239,221)	93,860	34,471
Pensions and other postretirement benefits	(29,004)	5,636	7,932
Other comprehensive (loss) income, net of tax, attributable to TD Group	(383,081)	89,243	64,644
TOTAL COMPREHENSIVE INCOME	$ 506,689	$ 1,046,305	$ 661,531

Consolidated Statement of Chang

Consolidated Statement of Changes in Stockholders' Deficit - USD ($) $ in Thousands	Total	Common Stock	Additional Paid-In Capital	Accumulated Deficit	Noncontrolling Interest [Member]	Accumulated Other Comprehensive (Loss) Income	Treasury Stock
NONCONTROLLING INTERESTS					$ 0
BALANCE (in shares)							(2,433,035)
Other comprehensive loss, net of tax	$ 64,644
BALANCE (in shares) at Sep. 30, 2016		55,767,767
BALANCE at Sep. 30, 2016	(651,490)	$ 558	$ 1,028,972	$ (1,146,963)		$ (149,787)	$ (384,270)
Accrued unvested dividend equivalent payments and other	(214,849)			(214,849)
Compensation expense recognized for employee stock options and restricted stock	44,931		44,931
Exercise of employee stock options, restricted stock activity and other, net	20,550	$ 3	21,177				$ (630)
Exercise of employee stock options and restricted stock activity, net (in shares)		324,908					(2,548)
Treasury stock purchased	(389,821)						$ (389,821)
Treasury stock purchased (in shares)							(1,723,624)
Common stock issued	239		239
Common stock issued (in shares)		984
NET INCOME ATTRIBUTABLE TO TD GROUP	596,887			596,887
Net Income (Loss), Including Portion Attributable to Noncontrolling Interest	596,887
Interest rate swaps and caps, net of tax	34,471					34,471
Foreign currency translation	22,241					22,241
Pension liability adjustments, net of tax	7,932					7,932
BALANCE at Sep. 30, 2017	(2,951,204)	$ 561	1,095,319	(3,187,220)		(85,143)	$ (774,721)
BALANCE (in shares) at Sep. 30, 2017		56,093,659
NONCONTROLLING INTERESTS					0
BALANCE (in shares)							(4,159,207)
Other comprehensive loss, net of tax	89,243
Accrued unvested dividend equivalent payments and other	(16,420)			(16,420)
Compensation expense recognized for employee stock options and restricted stock	55,481		55,481
Exercise of employee stock options, restricted stock activity and other, net	57,008	$ 8	57,583				$ (583)
Exercise of employee stock options and restricted stock activity, net (in shares)		800,955					(2,119)
Common stock issued	359		359
Common stock issued (in shares)		1,072
NET INCOME ATTRIBUTABLE TO TD GROUP	957,062			957,062
Net Income (Loss), Including Portion Attributable to Noncontrolling Interest	957,062
Interest rate swaps and caps, net of tax	93,860					93,860
Foreign currency translation	(10,253)					(10,253)
Pension liability adjustments, net of tax	5,636					5,636
BALANCE at Sep. 30, 2018	$ (1,808,471)	$ 569	1,208,742	(2,246,578)		4,100	$ (775,304)
BALANCE (in shares) at Sep. 30, 2018	56,895,686	56,895,686
NONCONTROLLING INTERESTS	$ 0				0
BALANCE (in shares)	4,161,326						(4,161,326)
Total stockholders’ deficit	$ (1,808,471)
Cumulative Effect on Retained Earnings, Net of Tax | Accounting Standards Update 2014-09 [Member]	3,284			3,284
Cumulative Effect on Retained Earnings, Net of Tax | Accounting Standards Update 2016-16 [Member]	(353)			(353)
Cumulative Effect on Retained Earnings, Net of Tax | Accounting Standards Update 2018-02 [Member]	0			2,199
Other comprehensive loss, net of tax	(383,081)
Other comprehensive loss, net of tax | Accounting Standards Update 2018-02 [Member]				(2,199)
Equity of noncontrolling interest acquired	8,281				8,281
Dividends paid	(1,687,910)			(1,687,910)
Accrued unvested dividend equivalent payments and other	(80,368)			(80,368)
Compensation expense recognized for employee stock options and restricted stock	87,727		87,727
Exercise of employee stock options, restricted stock activity and other, net	81,882	$ 7	81,875
Exercise of employee stock options and restricted stock activity, net (in shares)		726,750
Common stock issued	416		416
Common stock issued (in shares)		875
NET INCOME ATTRIBUTABLE TO TD GROUP	889,770			889,770
Net Income (Loss) from Noncontrolling Interest					1,541
Net Income (Loss), Including Portion Attributable to Noncontrolling Interest	891,311
Interest rate swaps and caps, net of tax	(239,221)					(114,856)
Other Comprehensive Loss, Derivatives Qualifying as Hedges	(237,022)
Foreign currency translation	(114,856)					(237,022)
Pension liability adjustments, net of tax	(29,004)					(29,004)
BALANCE at Sep. 30, 2019	$ (2,894,905)	$ 576	$ 1,378,760	$ (3,119,956)		$ (378,981)	$ (775,304)
BALANCE (in shares) at Sep. 30, 2019	57,623,311	57,623,311
NONCONTROLLING INTERESTS	$ 9,822				$ 9,822
BALANCE (in shares)	4,161,326						(4,161,326)
Total stockholders’ deficit	$ (2,885,083)

Consolidated Statements of Cash

Consolidated Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2017
OPERATING ACTIVITIES:
Net income including noncontrolling interests	$ 891,311	$ 957,062	$ 596,887
Net (income) loss from discontinued operations	(50,432)	4,474	31,654
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation	89,689	56,397	50,937
Amortization of intangible assets	136,011	73,447	90,088
Amortization of debt issuance costs, original issue discount and premium	28,034	22,128	21,106
Amortization of inventory step-up	76,927	7,080	20,621
Amortization of loss contract reserves	(38,347)	(10,570)	(3,477)
Refinancing costs	3,013	6,396	39,807
Non-cash stock compensation	93,362	58,481	45,524
Deferred income taxes	(349)	(151,640)	(918)
Changes in assets/liabilities, net of effects from acquisitions and sales of businesses:
Trade accounts receivable	(82,268)	(43,811)	(54,669)
Inventories	(35,712)	(17,888)	5,127
Income taxes receivable/payable	(2,667)	36,161	18,219
Other assets	(26,767)	(4,813)	(10,564)
Accounts payable	(1,632)	18,075	(10,354)
Accrued interest	(3,948)	14,368	(958)
Accrued and other liabilities	(60,753)	(3,174)	(50,297)
Net cash provided by operating activities	1,015,472	1,022,173	788,733
INVESTING ACTIVITIES:
Capital expenditures, net of disposals	(101,591)	(73,341)	(71,013)
Payments made in connection with acquisitions	(3,976,155)	(667,619)	(215,990)
Proceeds in connection with the sale of discontinued operations	188,766	57,383	0
Net cash used in investing activities	(3,888,980)	(683,577)	(287,003)
FINANCING ACTIVITIES:
Proceeds from exercise of stock options	81,875	57,583	21,177
Special dividends and dividend equivalent payments	(1,712,219)	(56,148)	(2,581,552)
Treasury stock purchased	0	0	(389,821)
Proceeds from term loans, net	0	12,779,694	2,937,773
Repayments on term loans	(76,428)	(12,174,305)	(1,284,698)
Proceeds from senior secured notes due 2026, net	3,935,567	0	0
Proceeds from senior subordinated notes, net	544,248	489,608	300,386
Cash tender and redemption of senior subordinated notes due 2020	(550,000)	0	0
Cash tender and redemption of senior subordinated notes due 2021, including premium	0	0	(528,847)
Proceeds from trade receivable securitization facility, net	49,423	0	99,471
Financing fees and other	(1,113)	(10,832)	(17,571)
Net cash provided by (used in) financing activities	2,271,353	1,085,600	(1,443,682)
EFFECT OF EXCHANGE RATE CHANGES ON CASH AND CASH EQUIVALENTS	(3,376)	(1,740)	5,519
NET (DECREASE) INCREASE IN CASH AND CASH EQUIVALENTS	(605,531)	1,422,456	(936,433)
CASH AND CASH EQUIVALENTS, BEGINNING OF PERIOD	2,073,017	650,561	1,586,994
CASH AND CASH EQUIVALENTS, END OF PERIOD	1,467,486	2,073,017	650,561
SUPPLEMENTAL DISCLOSURE OF CASH FLOW INFORMATION:
Cash paid during the period for interest	877,531	634,980	587,718
Cash paid during the period for income taxes	$ 215,154	$ 129,246	$ 185,295

DESCRIPTION OF THE BUSINESS

DESCRIPTION OF THE BUSINESS	12 Months Ended
	Sep. 30, 2019
Accounting Policies [Abstract]
DESCRIPTION OF THE BUSINESS	DESCRIPTION OF THE BUSINESS Description of the Business – TransDigm Group Incorporated (“TD Group”), through its wholly-owned subsidiary, TransDigm Inc., is a leading global designer, producer and supplier of highly engineered aircraft components for use on nearly every commercial and military aircraft in service today. TransDigm Inc., along with TransDigm Inc.’s direct and indirect wholly-owned operating subsidiaries (collectively, with TD Group, the “Company” or “TransDigm”), offers a broad range of proprietary aerospace components. TD Group has no significant assets or operations other than its 100% ownership of TransDigm Inc. TD Group’s common stock is listed on the New York Stock Exchange, or the NYSE, under the trading symbol “TDG.” TransDigm's major product offerings, substantially all of which are ultimately provided to end-users in the aerospace industry, include mechanical/electro-mechanical actuators and controls, ignition systems and engine technology, specialized pumps and valves, power conditioning devices, specialized AC/DC electric motors and generators, NiCad batteries and chargers, engineered latching and locking devices, rods and locking devices, engineered connectors and elastomers, databus and power controls, cockpit security components and systems, specialized cockpit displays, aircraft audio systems, specialized lavatory components, seat belts and safety restraints, engineered interior surfaces and related components, advanced sensor products, switches and relay panels, advanced displays, thermal protection and insulation, lighting and control technology, military personnel parachutes, high performance hoists, winches and lifting devices, and cargo loading, handling and delivery systems.

ACQUISITIONS

ACQUISITIONS	12 Months Ended
	Sep. 30, 2019
Business Combinations [Abstract]
ACQUISITIONS	ACQUISITIONS AND DIVESTITURES During the most recent three fiscal years, the Company completed the acquisitions of Esterline, Skandia, Extant, Kirkhill and substantially all of the assets and technical data rights of several aerospace and defense-related product lines. The Company accounted for the acquisitions using the acquisition method and included the results of operations of the acquisitions in its consolidated financial statements from the effective date of each acquisition. As of September 30, 2019 , the one-year measurement period is open for Esterline and certain product line acquisitions; therefore, the assets acquired and liabilities assumed related to these acquisitions are subject to adjustment until the end of their respective one-year measurement periods. Pro forma net sales and results of operations for the acquisitions other than Esterline, had they occurred at the beginning of the applicable fiscal year ended September 30, 2019 or 2018 , are not material and, accordingly, are not provided. The acquisitions strengthen and expand the Company’s position to design, produce and supply highly engineered proprietary aerospace components in niche markets with significant aftermarket content and provide opportunities to create value through the application of our three core value-driven operating strategies (obtaining profitable new business, improving our cost structure, and providing highly engineered value-added products to customers). The purchase price paid for each acquisition reflects the current earnings before interest, taxes, depreciation and amortization (EBITDA) and cash flows, as well as the future EBITDA and cash flows expected to be generated by the business, which are driven in most cases by the recurring aftermarket consumption over the life of a particular aircraft, estimated to be approximately 25 to 30 years . Acquisitions Esterline – On March 14, 2019, TransDigm completed the acquisition of all the outstanding stock of Esterline for $122.50 per share in cash, plus the repayment of Esterline debt. The purchase price, net of cash acquired of approximately $398.2 million , totaled approximately $3,923.9 million . Of the $3,923.9 million purchase price, $3,536.3 million was paid at closing and the remaining $387.6 million was classified as restricted cash for the redemption of Esterline’s outstanding senior notes due 2023 (herein the "2023 Notes"). The 2023 Notes were redeemed on April 15, 2019. Esterline, through its subsidiaries, is an industry leader in specialized manufacturing for the aerospace and defense industry, primarily within three core disciplines: advanced materials, avionics and controls and sensors and systems. The acquisition of Esterline expands TransDigm's platform of proprietary and sole source content for the aerospace and defense industry and the Esterline products have significant aftermarket exposure. TransDigm evaluated the strategic fit and description of each Esterline reporting unit to determine the appropriate business segment for the reporting unit. Each Esterline reporting unit is included in one of TransDigm's segments: Power and Control, Airframe, or Non-aviation. Refer to Note 17, "Segments," for additional information about the Company's segments. The total purchase price of Esterline was allocated to the underlying assets acquired and liabilities assumed based upon management’s estimated fair values at the date of acquisition. To the extent the purchase price exceeded the estimated fair value of the net identifiable tangible and intangible assets acquired, such excess was allocated to goodwill. Allocations are based on the acquisition method of accounting and in-process third-party valuation appraisals. The allocation of the purchase price is preliminary and will likely change in future periods, perhaps materially, as fair value estimates of the assets acquired and liabilities assumed are refined and finalized during the allowable one year measurement period. Except where otherwise noted in the notes to consolidated financial statements, changes in balances and activity where comparable periods are presented in the consolidated financial statements were generally driven by the Esterline acquisition. The preliminary allocation of the fair value of the Esterline acquisition is summarized in the table below (presented in thousands). Assets acquired, excluding cash: Trade accounts receivable $ 386,671 Inventories 588,741 Prepaid expenses and other current assets 421,973 Property, plant, and equipment 472,623 Other intangible assets 1,309,900 Goodwill 2,176,941 Other 22,196 Total assets acquired, excluding cash 5,379,045 Liabilities assumed: Accounts payable 144,516 Other current liabilities 717,621 Other noncurrent liabilities 593,058 Total liabilities assumed 1,455,195 Net assets acquired $ 3,923,850 The Company currently expects that of the approximately $2.2 billion of goodwill recognized for the acquisition, approximately $25.6 million will be deductible for tax purposes and, of the approximately $1.3 billion of other intangible assets recognized for the acquisition, approximately $48.9 million will be deductible for tax purposes. In connection with the Esterline acquisition, we acquired existing long-term contracts with customers that were incurring gross margin losses as of the date of acquisition. Based on our review of these contracts, we concluded that the terms of certain contracts were unfavorable when compared to market terms as of the acquisition date. As a result, we recognized loss contract reserves as of the acquisition date of $268.4 million based on the present value of the difference between the contractual cash flows of the existing long-term contracts and the estimated cash flows had the contracts been executed at market terms as of the acquisition date. As of September 30, 2019, we have reclassified $9.3 million in loss contract reserves to liabilities held-for-sale, as it pertains to Souriau-Sunbank. Significant assumptions used to determine the fair value of the loss contract reserves using the discounted cash flow model include discount rates, forecasted quantities of products to be sold under the long-term contracts and market prices for respective products. These significant assumptions are forward looking and could be affected by future economic and market conditions. The loss contract reserves are amortized and recorded as an offset to cost of sales over the life of the contracts as actual sales occur under the long-term contracts. Approximately $27.3 million was amortized and recorded as an offset to cost of sales in the consolidated statement of income for the fiscal year ended September 30, 2019. Total loss contract reserves related to the Esterline acquisition were $231.8 million at September 30, 2019, of which $60.0 million is classified in accrued liabilities and $171.8 million is classified in other non-current liabilities in the consolidated balance sheet at September 30, 2019. The Esterline acquisition contributed net sales and income from continuing operations before taxes of $908.0 million and $57.1 million for the fiscal year ended September 30, 2019 . Net income from continuing operations for the fiscal year ended September 30, 2019 included approximately $55.4 million of other intangible asset amortization expense and $71.4 million of inventory step-up amortization expense in cost of sales. Acquisition costs were expensed as incurred and for the fiscal year ended September 30, 2019 totaled approximately $85.1 million . These costs were recorded in selling and administrative expenses and cost of sales within the consolidated statements of income. In connection with the financing of the Esterline acquisition, approximately $155.3 million of net interest expense (comprised of gross interest expense of $163.5 million and interest income of $8.2 million ) was recorded for the fiscal year ended September 30, 2019 . The following pro forma information presents consolidated financial information as if Esterline had been acquired at the beginning of fiscal year 2018. Interest expense has been adjusted as though the debt incurred to finance the Esterline acquisition had been outstanding at October 1, 2017. In the pro forma information presented, fiscal year 2018 includes other intangible asset amortization expense of approximately $103.3 million resulting from the preliminary acquisition accounting. In the pro forma information presented, fiscal year 2019 presented includes other intangible asset amortization of approximately $71.5 million resulting from the preliminary acquisition accounting. In the pro forma information presented, fiscal years 2018 and 2019 include property step-up depreciation of approximately $14.4 million resulting from the preliminary acquisition accounting. The full $71.4 million of inventory step-up amortization resulting from the preliminary acquisition accounting asset step-up has been included in the fiscal year 2018 pro forma results to reflect the pro forma transaction date of October 1, 2017, and thus the inventory step-up amortization expense of $71.4 million recorded for the fiscal year ended September 30, 2019, has been excluded. The unaudited pro forma consolidated financial information does not necessarily reflect the actual results that would have occurred had the acquisition taken place on October 1, 2017 , nor is it meant to be indicative of future results of operations of the combined companies under the ownership and operation of the Company. (Amounts in thousands, except per share amounts) Fiscal Year Ended September 30, 2019 September 30, 2018 Net sales $ 5,860,561 $ 5,291,760 Income from continuing operations attributable to TD Group $ 847,055 $ 551,211 Net earnings per share attributable to TD Group stockholders from continuing operations - basic and diluted $ 13.08 $ 8.90 Skandia – On July 13, 2018, the Company acquired all of the outstanding stock of Skandia for a total purchase price of approximately $84.3 million , which is net of a $0.2 million working capital settlement paid in the fourth quarter of fiscal 2018. Skandia provides highly engineered seating foam, foam fabrication, flammability testing and acoustic solutions for the business jet market. Skandia is included as a product line within an existing reporting unit in TransDigm's Airframe segment. No goodwill recognized for the acquisition is deductible for tax purposes. Extant – On April 24, 2018, the Company acquired all of the outstanding stock of Extant for a total purchase price of approximately $533.1 million in cash, which is net of a $0.2 million working capital settlement received in the third quarter of fiscal 2018. Extant provides a broad range of proprietary aftermarket products and repair and overhaul services to the aerospace and defense end markets. Extant is included in TransDigm's Power and Control segment. Prior to the Company's acquisition of Extant, Extant was owned by an equity fund sponsored by Warburg Pincus LLC. Michael Graff, a director of TransDigm, is a managing director of Warburg Pincus LLC and was chairman of the board of Extant. Robert Henderson, Vice Chairman of TransDigm, was also on the board of Extant and owned less than 2% of Extant on a fully diluted basis. In addition, Mr. Graff, Mr. W. Nicholas Howley, TransDigm's Executive Chairman, Mr. Douglas Peacock, then a director of TransDigm and now a retired director emeritus, and Mr. David Barr, a director of TransDigm, each had minority interests of less than 1% in the Warburg Pincus LLC fund that owned Extant. The total purchase price of Extant was allocated to the underlying assets acquired and liabilities assumed based upon the fair values at the date of acquisition. To the extent the purchase price exceeded the fair value of the net identifiable tangible and intangible assets acquired, such excess was allocated to goodwill. The following table summarizes the purchase price allocation of the fair values of the assets acquired and liabilities assumed at the transaction date (presented in thousands). Assets acquired: Current assets, excluding cash acquired $ 53,325 Property, plant, and equipment 4,103 Intangible assets 105,000 Goodwill 407,046 Total assets acquired 569,474 Liabilities assumed: Current liabilities 9,876 Other noncurrent liabilities 26,453 Total liabilities assumed 36,329 Net assets acquired $ 533,145 Approximately $62.5 million of the $105.0 million other intangible assets recognized for the acquisition is deductible for tax purposes over 15 years. Of the $407.0 million of goodwill recognized for the acquisition, approximately $12.4 million is deductible for tax purposes. Extant Acquisitions - On August 30, 2019, the Company's Extant subsidiary completed the acquisition of substantially all of the assets and technical data rights of the Stormscope product line from L3Harris Technologies, Inc. for approximately $20 million in cash. Stormscope is a lightning detection system for the general aviation market. Stormscope is included as a product line of Extant, which is included in TransDigm's Power and Control segment. The Company expects that approximately $11.1 million of goodwill recognized for the acquisition and approximately $7.5 million of other intangible assets recognized for the acquisition will be deductible for tax purposes over 15 years. On October 1, 2018, the Company's Extant subsidiary completed the acquisition of substantially all of the assets and technical data rights of the Corona, California operations of NavCom for approximately $27 million in cash. NavCom develops, manufactures, and supports high-reliability, mission-critical electronics, avionics and sub-assemblies. NavCom is included as a product line of Extant, which is included in TransDigm's Power and Control segment. Approximately $9.0 million of goodwill recognized for the acquisition is deductible for tax purposes over 15 years. Kirkhill – On March 15, 2018, the Company acquired the assets and certain liabilities of the Kirkhill elastomers business from Esterline Technologies for a total purchase price of approximately $49.3 million , which is net of a $0.6 million working capital settlement received in the third quarter of fiscal 2018. Kirkhill, headquartered in Brea, California, is a leading supplier of highly engineered aerospace elastomers. Kirkhill's products are primarily proprietary, sole source with significant aftermarket content and used in a broad variety of most major commercial transport and military platforms. Kirkhill is included in TransDigm's Airframe segment. No goodwill recognized for the acquisition is deductible for tax purposes. Third Quarter Fiscal 2017 Acquisitions – The Company completed three product line acquisitions within the third quarter of fiscal 2017. The third quarter fiscal 2017 acquisitions were acquired for an aggregate purchase price of approximately $106.7 million in cash, which includes working capital settlements totaling $1.0 million paid in the third and fourth quarters of fiscal 2017 and an earn-out of $0.4 million paid in the second quarter of fiscal 2018. All three product lines consist primarily of proprietary, sole source products with significant aftermarket content. The products include highly engineered aerospace controls, quick disconnect couplings, and communication electronics. Each product line acquired was consolidated into an existing TransDigm reporting unit within TransDigm's Power & Control segment. Approximately $66.0 million of goodwill recognized for the acquisitions is deductible for tax purposes over 15 years and approximately $9.0 million of goodwill recognized for the acquisitions is not deductible for tax purposes. Divestitures Souriau-Sunbank Companies – On July 21, 2019, TransDigm entered into a binding offer (the “Put Agreement”) with Eaton Corporation plc (“Eaton”) for the acquisition by Eaton of the shares of Souriau SAS, Souriau USA Inc. and Sunbank Family of Companies LLC which comprise the Souriau-Sunbank Connection Technologies business (“Souriau-Sunbank”). Pursuant to the terms of the Put Agreement, after completion of the consultation process with the French works council, TransDigm has the right to require Eaton to enter into a securities purchase agreement (the “Purchase Agreement”) providing for the purchase by Eaton from TransDigm of the shares of Souriau-Sunbank. The Purchase Agreement was entered into by the parties on October 28, 2019. Pursuant to the terms of the Purchase Agreement, Eaton will purchase the shares of the Souriau-Sunbank for a cash purchase price of approximately $920 million . The transaction is subject to execution and delivery of the Purchase Agreement and other definitive agreements, the satisfaction or waiver of customary closing conditions and receipt of required regulatory approvals, all of which have been received other than the French foreign investment approval. The parties expect to complete the transaction during the first quarter of fiscal 2020. Souriau-Sunbank is classified as held-for-sale as of September 30, 2019. The results of operations of Souriau-Sunbank are presented in discontinued operations in the accompanying consolidated financial statements for all periods presented since the date acquired (refer to Note 23, “Discontinued Operations”). Esterline Interface Technology Group – On September 20, 2019, TransDigm completed the divestiture of its Esterline Interface Technology (“EIT”) group of businesses to an affiliate of KPS Capital Partners, LP for approximately $190 million . EIT was acquired by TransDigm as part of its acquisition of Esterline in March 2019. The results of operations of EIT are presented in discontinued operations in the accompanying consolidated financial statements for all periods presented since the date acquired (refer to Note 23, “Discontinued Operations”). Schroth – On February 22, 2017, the Company acquired all of the outstanding stock of Schroth Safety Products GmbH and certain aviation and defense assets and liabilities from subsidiaries of Takata Corporation (collectively, "Schroth"), for a total purchase price of approximately $89.7 million , of which consisted primarily of $79.7 million paid in cash during fiscal 2017 and an approximately $9.0 million indemnity holdback, of which $8.5 million was paid in April 2018 and $0.5 million remains a reserve as of September 30, 2019. In connection with the settlement of a Department of Justice investigation into the competitive effects of the acquisition, during the fourth quarter of 2017, the Company committed to divest of the Schroth business. Therefore, Schroth was classified as held-for-sale beginning in the fourth quarter of 2017. The results of operations of Schroth are presented in discontinued operations in the accompanying consolidated financial statements for all periods presented. On January 26, 2018, the Company completed the sale of Schroth in a management buyout to a private equity fund and certain members of Schroth management for approximately $61.4 million , which includes a working capital adjustment of $0.3 million

SUMMARY OF SIGNIFICANT ACCOUNTI

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES	12 Months Ended
	Sep. 30, 2019
Accounting Policies [Abstract]
SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES	SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES Basis of Presentation and Consolidation —The accompanying consolidated financial statements were prepared in conformity with generally accepted accounting principles in the United States (“GAAP”) and include the accounts of TD Group and subsidiaries. All significant intercompany balances and transactions have been eliminated. Certain reclassifications have been made to the prior year consolidated financial statements to conform to current year classifications related to the adoption of ASU 2017-07, "Compensation—Retirement Benefits (ASC 715), impacting the presentation of the net periodic benefit cost in the consolidated statements of income. The accounting pronouncement and impact of the fiscal year 2019 adoption of the pronouncement on the consolidated financial statements is summarized in Note 4, "Recent Accounting Pronouncements." The Esterline businesses were acquired during the second quarter of fiscal 2019 and preliminarily assessed as a separate segment of the Company. During the third quarter of fiscal 2019, the Esterline businesses were integrated into TransDigm's existing Power & Control, Airframe and Non-aviation segments. For financial information about our segments, see Note 17, "Segments." Revenue Recognition —The Company adopted Accounting Standards Codification (“ASC”) 606, “Revenue from Contracts with Customers,” in the first quarter of fiscal 2019 using the modified retrospective method. The adoption of this standard did not have a material impact on our consolidated results of operations, financial position or cash flows. The results for periods before fiscal 2019 were not restated for the new standard and the cumulative effect of the change in accounting was recognized through retained earnings at the date of adoption. Refer to Note 5, "Revenue Recognition," for additional disclosures relating to ASC 606. Revenue is recognized from the sale of products when control transfers to the customer, which is demonstrated by our right to payment, a transfer of title, a transfer of the risk and rewards of ownership, or the customer acceptance, but most frequently upon shipment where the customer obtains physical possession of the goods. The majority of the Company's revenue is recorded at a point in time. Sales recognized over time are generally accounted for using an input measure to determine progress completed at the end of the period. Sales for service contracts generally are recognized as the services are provided. For agreements with multiple performance obligations, judgment is required to determine whether performance obligations specified in these agreements are distinct and should be accounted for as separate revenue transactions for recognition purposes. Shipping and Handling Costs —Shipping and handling costs are included in cost of sales in the consolidated statements of income. Research and Development Costs —The Company expenses research and development costs as incurred and classifies such amounts in selling and administrative expenses. The expense recognized for research and development costs for the fiscal years ended September 30, 2019 , 2018 and 2017 was approximately $116.8 million , $73.8 million , and $73.8 million , respectively. Cash Equivalents —The Company considers all highly liquid investments with a maturity of three months or less when purchased to be cash equivalents. Allowance for Uncollectible Accounts —The Company reserves for amounts determined to be uncollectible based on specific identification of losses and estimated losses based on historical experience. The allowance also incorporates a provision for the estimated impact of disputes with customers. The determination of the amount of the allowance for uncollectible accounts is subject to significant levels of judgment and estimation by management. If circumstances change or economic conditions deteriorate or improve, the allowance for uncollectible accounts could increase or decrease. Inventories —Inventories are stated at the lower of cost or net realizable value. Cost of inventories is generally determined by the average cost and the first-in, first-out (FIFO) methods and includes material, labor and overhead related to the manufacturing process. Provision for potentially obsolete or slow-moving inventory is made based on management’s analysis of inventory levels and future sales forecasts. Property, Plant and Equipment —Property, plant and equipment are stated at cost and include improvements which significantly increase capacities or extend the useful lives of existing plant and equipment. Depreciation is computed using the straight-line method over the following estimated useful lives: land improvements from 10 to 20 years, buildings and improvements from 5 to 30 years, machinery and equipment from 2 to 10 years and furniture and fixtures from 3 to 10 years. Net gains or losses related to asset dispositions are recognized in earnings in the period in which dispositions occur. Routine maintenance, repairs and replacements are expensed as incurred. Amortization expense of assets accounted for as capital leases is included with depreciation expense. Property, plant and equipment is assessed for potential impairment whenever indicators of impairment are present by determining whether the carrying value of the property can be recovered through projected, undiscounted cash flows from future operations over the property’s remaining estimated useful life. Any impairment recognized is the amount by which the carrying amount exceeds the fair value of the asset. Fair value is measured based on quoted market prices in active markets, if available. If quoted market prices are not available, the estimate of fair value is based on various valuation techniques, including the discounted value of estimated future cash flows. Debt Issuance Costs, Premiums and Discounts —The cost of obtaining financing as well as premiums and discounts are amortized using the effective interest method over the terms of the respective obligations as a component of interest expense within the consolidated statements of income. Debt issuance costs are presented in the consolidated balance sheets as a direct reduction from the carrying amount of the related debt liabilities. Financial Instruments —Interest rate swap and cap agreements are used to manage interest rate risk associated with floating-rate borrowings under our credit facility. The interest rate swap and cap agreements utilized by the Company effectively modify the Company’s exposure to interest rate risk by converting a portion of the Company’s floating-rate debt to a fixed rate basis through the expiration date of the interest rate swap and cap agreements, thereby reducing the impact of interest rate changes on future interest expense. These agreements involve the receipt of floating rate amounts in exchange for fixed rate interest payments over the term of the agreements without an exchange of the underlying principal amount. These derivative instruments qualify as effective cash flow hedges under GAAP. The Company transacts business in various foreign currencies, which subjects the Company’s cash flows and earnings to exposure related to changes in foreign currency exchange rates. These exposures arise primarily from purchases or sales of products and services from third parties. Foreign currency forward exchange contracts provide for the purchase or sale of foreign currencies at specified future dates at specified exchange rates, and are used to offset changes in the fair value of certain assets or liabilities or forecasted cash flows resulting from transactions denominated in foreign currencies. For the interest rate swap and cap agreements and the foreign currency forward contracts designated as cash flow hedges, the effective portion of the gain or loss from the financial instruments was initially reported as a component of accumulated other comprehensive loss in stockholders’ deficit and subsequently reclassified into earnings in the same line as the hedged item in the same period or periods during which the hedged item affected earnings. As the interest rate swap and cap agreements are used to manage interest rate risk, any gains or losses from the derivative instruments that are reclassified into earnings are recognized in interest expense - net in the consolidated statements of income. As the foreign currency forward exchange contracts are used to manage foreign currency exposure primarily arising from purchases or sales from third parties, any gains or losses from the derivative instruments that are reclassified into earnings are recognized in cost of sales or selling and administrative expenses in the consolidated statements of income. Goodwill and Other Intangible Assets —In accordance with ASC 805, “Business Combinations,” the Company uses the acquisition method of accounting to allocate costs of acquired businesses to the assets acquired and liabilities assumed based on their estimated fair values at the dates of acquisition. The excess costs of acquired businesses over the fair values of the assets acquired and liabilities assumed were recognized as goodwill. The valuations of the acquired assets and liabilities assumed will impact the determination of future operating results. Determining the fair value of assets acquired and liabilities assumed requires management’s judgment and often involves the use of significant estimates and assumptions, including assumptions with respect to future cash inflows and outflows, revenue growth rates, discount rates, customer attrition rates, royalty rates, asset lives and market multiples, among other items. We determine the fair values of intangible assets acquired generally in consultation with third-party valuation advisors. Fair value adjustments to the Company’s assets and liabilities are recognized and the results of operations of the acquired business are included in our consolidated financial statements from the effective date of the merger or acquisition. Intangible assets other than goodwill are recognized if the benefit of the intangible asset is obtained through contractual or other legal rights, or if the intangible asset can be sold, transferred, licensed or exchanged, regardless of the Company’s intent to do so. Goodwill is the excess of the purchase price paid over the estimated fair value of the net assets of a business acquired. Other intangible assets consist of identifiable intangibles acquired or recognized in accounting for the acquisitions (trademarks, trade names, technology, customer relationships, order backlog and other intangible assets). Goodwill and intangible assets that have indefinite useful lives (i.e., trademarks and trade names) are subject to annual impairment testing. Management determines fair value using a discounted future cash flow analysis or other accepted valuation techniques. The Company performs an annual impairment test for goodwill and other intangible assets as of the first day of the fourth fiscal quarter of each year, or more frequently, if an event occurs or circumstances change that would more likely than not reduce fair value below current value. At the time of goodwill impairment testing, the Company first assesses qualitative factors to determine whether it is more likely than not that the fair value of a reporting unit is less than its carrying amount, and whether it is therefore necessary to perform the quantitative goodwill impairment test. The quantitative goodwill impairment test consists of two steps. The first step of the goodwill impairment test, used to identify potential impairment, compares the fair value of a reporting unit (as defined) with its carrying amount, including goodwill. If the fair value of the reporting unit exceeds its carrying amount, goodwill is not considered impaired, and the second step of the goodwill impairment test is unnecessary. The second step measures the amount of impairment, if any, by comparing the carrying value of the goodwill associated with a reporting unit to the implied fair value of the goodwill derived from the estimated overall fair value of the reporting unit and the individual fair values of the other assets and liabilities of the reporting unit. GAAP requires that the annual, and any interim, impairment assessment be performed at the reporting unit level. The reporting unit level is one level below an operating segment. Substantially all goodwill was determined and recognized for each reporting unit pursuant to the accounting for the merger or acquisition as of the date of each transaction. With respect to acquisitions integrated into an existing reporting unit, any acquired goodwill is combined with the goodwill of the reporting unit. The impairment test for indefinite lived intangible assets consists of a comparison between their fair values and carrying values. If the carrying amounts of intangible assets that have indefinite useful lives exceed their fair values, an impairment loss will be recognized in an amount equal to the sum of any such excesses. The Company assesses the recoverability of its amortizable intangible assets only when indicators of impairment are present by determining whether the amortization over their remaining lives can be recovered through projected, undiscounted cash flows from future operations. Amortization of amortizable intangible assets is computed using the straight-line method over the following estimated useful lives: technology from 20 to 22 years, order backlog from 1 year to 1.5 years, customer relationships over 20 years and other intangible assets over 20 years. Stock-Based Compensation —The Company records stock-based compensation expense using the Black-Scholes pricing model based on certain valuation assumptions. Compensation expense is recorded over the vesting periods of the stock options. The Company has classified stock-based compensation primarily within selling and administrative expenses to correspond with the classification of employees that receive stock option grants. No expense is recognized for any stock options ultimately forfeited because the recipients fail to meet vesting requirements. Income Taxes —The provision for income taxes is calculated using the asset and liability method. Under the asset and liability method, deferred income taxes are recognized for the tax effect of temporary differences between the financial statement carrying amount of assets and liabilities and the amounts used for income tax purposes and for certain changes in valuation allowances. Valuation allowances are recorded to reduce certain deferred tax assets when, in our estimation, it is more likely than not that a tax benefit will not be realized. Contingencies —During the ordinary course of business, the Company is from time to time threatened with, or may become a party to, legal actions and other proceedings. While the Company is currently involved in certain legal proceedings, it believes the results of these proceedings will not have a material adverse effect on its financial condition, results of operations, or cash flows. Estimates —The preparation of financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities at the date of the financial statements and the reported amounts of revenues and expenses during the reporting period. Actual results could differ from those estimates. Comprehensive Income (Loss) —The term “comprehensive income (loss)” represents the change in stockholders’ equity (deficit) from transactions and other events and circumstances resulting from non-stockholder sources. The Company’s accumulated other comprehensive income or loss, consisting principally of fair value adjustments to its interest rate swap and cap agreements (net of tax), cumulative foreign currency translation adjustments and pension liability adjustments (net of tax), is reported separately in the accompanying consolidated statements of comprehensive income. Foreign Currency Translation and Transactions —The assets and liabilities of subsidiaries located outside the United States are translated into U.S. dollars at the rates of exchange in effect at the balance sheet dates. Revenue and expense items are translated at the average monthly exchange rates prevailing during the period. Gains and losses resulting from foreign currency transactions are recognized currently in income, and those resulting from translation of financial statements are accumulated as a separate component of other comprehensive income (loss) for the period. Foreign currency gains or losses recognized currently in income from changes in exchange rates were immaterial to our results of operations. Earnings per Share —Earnings per share information is determined using the two-class method, which includes the weighted-average number of common shares outstanding during the period and other securities that participate in dividends (“participating securities”). Our vested stock options are considered “participating securities” because they include non-forfeitable rights to dividends. In applying the two-class method, earnings are allocated to both common stock shares and participating securities based on their respective weighted-average shares outstanding for the period. Diluted earnings per share information may include the additional effect of other securities, if dilutive, in which case the dilutive effect of such securities is calculated using the treasury stock method. Contingently issuable shares are not included in earnings per share until the period in which the contingency is satisfied; therefore, basic and diluted earnings per share are the same. Pension Benefits —The Company accounts for pension expense using the end of the fiscal year as our measurement date. Management selects appropriate assumptions including the discount rate, rate of increase in future compensation levels and assumed long-term rate of return on plan assets. The assumptions are based upon historical results, the current economic environment and reasonable expectations of future events. Actual results which vary from our assumptions are accumulated and amortized over future periods, and accordingly, are recognized in expense in these periods. Significant differences between the assumptions and actual experience or significant changes in assumptions could impact the pension costs and the pension obligation.

RECENT ACCOUNTING PRONOUNCEMENT

RECENT ACCOUNTING PRONOUNCEMENTS	12 Months Ended
	Sep. 30, 2019
New Accounting Pronouncements and Changes in Accounting Principles [Abstract]
RECENT ACCOUNTING PRONOUNCEMENTS	RECENT ACCOUNTING PRONOUNCEMENTS In May 2014, the FASB issued Accounting Standards Update (“ASU”) 2014-09, which created a new topic in the Accounting Standards Codification (“ASC”) 606, “Revenue from Contracts with Customers.” In addition to superseding and replacing nearly all existing U.S. GAAP revenue recognition guidance, including industry-specific guidance, ASC 606 requires an entity to recognize revenue in a manner that depicts the transfer of promised goods or services to customers in an amount that reflects the consideration to which the entity expects to be entitled in exchange for those goods or services. The standard also specifies the accounting of some costs to obtain or fulfill a contract with a customer and expands the disclosure requirements around contracts with customers. The Company adopted this standard in the first quarter of 2019 using the modified retrospective method. The adoption of this standard did not have a material impact on our consolidated results of operations, financial position or cash flows. The results for periods before fiscal 2019 were not restated for the new standard and the cumulative effect of the change in accounting was recognized through retained earnings at the date of adoption. Refer to Note 5, "Revenue Recognition," for additional disclosures relating to ASC 606. In February 2016, the FASB issued ASU 2016-02, “Leases (ASC 842),” which requires lessees to recognize a right-of-use asset and lease liability for all leases with a term of more than 12 months. ASU 2016-02 is effective for us on October 1, 2019, and requires a modified retrospective application. In July 2018, the FASB issued ASU 2018-11, “Leases (ASC 842) Targeted Improvements,” which provides an additional transition method that allows entities to initially apply the new standard at the adoption date and recognize a cumulative effect adjustment to the opening balance of retained earnings in the period of adoption without restating prior periods. We plan to utilize this transition method upon adoption, and as a result, we will not adjust comparative period financial information or make the new required lease disclosures for periods before the effective date. Our preparation for the adoption of ASC 842 is substantially complete. We have compiled an inventory of our lease agreements in order to determine the impact the new guidance will have on our financial statements and disclosures and have implemented new lease accounting software in preparation for the standard’s additional reporting requirements. We have elected certain practical expedients available under the guidance, including a package of practical expedients which allows us to not reassess prior conclusions related to contracts containing leases, lease classification, and initial direct costs. Based on our assessment to date, we expect that the adoption of ASC 842 will result in the recognition of right-of-use assets and corresponding lease liabilities of approximately 1% of total assets and liabilities, respectively, in our consolidated balance sheet as of October 1, 2019. We do not expect the new standard to have a material impact on our consolidated results of operations and cash flows. In June 2016, the FASB issued ASU 2016-13, "Financial Instruments—Credit Losses: Measurement of Credit Losses on Financial Instruments (ASU 2016-13)," which changes the impairment model for most financial assets. The new model uses a forward-looking expected loss method, which will generally result in earlier recognition of allowances for losses. ASU 2016-13 is effective for the Company for annual and interim periods beginning after October 1, 2020 and early adoption is permitted. The Company is currently evaluating the impact of adopting this standard on our consolidated financial statements and disclosures. In October 2016, the FASB issued ASU 2016-16, “Intra-Entity Transfers of Assets Other Than Inventory” (ASU 2016-16). This accounting standard requires companies to recognize the income tax effects of intercompany sales and transfers of assets, other than inventory, in the period in which the transfer occurs. Under previous guidance companies were required to defer the income tax effects of intercompany transfers of assets by recording prepaid taxes, until such assets were sold to an outside party or otherwise recognized. Current guidance requires companies to write off any income tax amounts previously deferred as prepaid taxes from past intercompany transactions, and to record deferred tax balances for amounts not previously recognized, through a cumulative-effect adjustment to retained earnings. ASU 2016-16 is effective for public business entities for fiscal years beginning after December 15, 2017, including interim periods within those years. The Company adopted this standard in the first quarter of fiscal 2019. The adoption of this standard did not have a material impact on our consolidated financial statements. Refer to the consolidated statements of stockholders' deficit for the impact of the adoption of ASU 2016-16 on retained earnings. In January 2017, the FASB issued ASU 2017-04, “Simplifying the Test for Goodwill Impairment,” to eliminate Step 2 from the goodwill impairment test in order to simplify the subsequent measurement of goodwill. The guidance is effective for the Company for fiscal years beginning after October 1, 2020, with early adoption permitted. The adoption of this standard is not expected to have a material impact on our consolidated financial statements and disclosures. In March 2017, the FASB issued ASU 2017-07, "Compensation—Retirement Benefits (ASC 715): Improving the Presentation of Net Periodic Pension Cost and Net Periodic Postretirement Benefit Cost," that changes how employers that sponsor defined benefit and/or other postretirement benefit plans present the net periodic benefit cost in the income statement. Under previous guidance, companies included all components of the net periodic benefit costs in the same lines as the service cost component. Current guidance requires employers to present the other components of the net periodic benefit costs separately from the line items that include the service cost and outside of any subtotal of operating income. In addition, only the service cost component will be eligible for capitalization in assets. Employers will have to disclose the lines used to present the other components of net periodic benefit cost, if the components are not presented separately in the income statement. The standard is effective for public business entities for fiscal years beginning after December 15, 2017, and interim periods within the fiscal year. The Company adopted this standard in the first quarter of fiscal 2019. The adoption of this standard did not have a material impact on our consolidated financial statements. In May 2017, the FASB issued ASU 2017-09, "Compensation—Stock Compensation (ASC 718): Scope of Modification Accounting," which provides clarity on which changes to the terms or conditions of share-based payment awards require an entity to apply the modification accounting provisions required in ASC 718. The standard is effective for all entities for annual periods beginning after December 15, 2017, with early adoption permitted, including adoption in any interim period for which financial statements have not yet been issued. The Company adopted this standard in the first quarter of fiscal 2019. The adoption of this standard did not have a material impact on our consolidated financial statements. In February 2018, the FASB issued ASU 2018-02, "Income Statement - Reporting Comprehensive Income (ASC 220): Reclassification of Certain Tax Effects from Accumulated Other Comprehensive Income," which gives entities the option to reclassify tax effects stranded in accumulated other comprehensive income as a result of the Tax Cuts and Jobs Act (the "Act") into retained earnings. The guidance allows entities to reclassify from accumulated other comprehensive income to retained earnings stranded tax effects resulting from the Act's new federal corporate income tax rate. The guidance also allows entities to elect to reclassify other stranded tax effects that relate to the Act but do not directly relate to the change in the federal tax rate (e.g., state taxes, changing from a worldwide tax system to a territorial system). Tax effects that are stranded in accumulated other comprehensive income for other reasons (e.g., prior changes in tax law, a change in valuation allowance) may not be reclassified. The standard is effective for the Company for fiscal years beginning after October 1, 2019, and interim periods within the fiscal year. Early adoption is permitted, including adoption in any interim period for which financial statements have not yet been issued. Entities have the option to apply the guidance retrospectively or in the period of adoption. As early adoption is permissible, the Company adopted the pronouncement beginning October 1, 2018. Changes were applied in the period of adoption and prior periods were not adjusted.The adoption of this standard did not have a material impact on our consolidated financial statements. In August 2018, the FASB issued ASU 2018-14, "Compensation - Retirement Benefits - Defined Benefit Plans - General (ASC 715-20)." ASU 2018-14 modifies disclosure requirements for employers that sponsor defined benefit pension or other postretirement plans. The ASU also requires an entity to disclose the weighted-average interest crediting rates for cash balance plans and to explain the reasons for significant gains and losses related to changes in the benefit obligation. The ASU is effective for the Company on October 1, 2020 and early adoption is permitted. The Company is currently evaluating the impact of adopting this standard on our consolidated financial statements and disclosures.
New Accounting Pronouncements, Policy [Policy Text Block]	RECENT ACCOUNTING PRONOUNCEMENTS In May 2014, the FASB issued Accounting Standards Update (“ASU”) 2014-09, which created a new topic in the Accounting Standards Codification (“ASC”) 606, “Revenue from Contracts with Customers.” In addition to superseding and replacing nearly all existing U.S. GAAP revenue recognition guidance, including industry-specific guidance, ASC 606 requires an entity to recognize revenue in a manner that depicts the transfer of promised goods or services to customers in an amount that reflects the consideration to which the entity expects to be entitled in exchange for those goods or services. The standard also specifies the accounting of some costs to obtain or fulfill a contract with a customer and expands the disclosure requirements around contracts with customers. The Company adopted this standard in the first quarter of 2019 using the modified retrospective method. The adoption of this standard did not have a material impact on our consolidated results of operations, financial position or cash flows. The results for periods before fiscal 2019 were not restated for the new standard and the cumulative effect of the change in accounting was recognized through retained earnings at the date of adoption. Refer to Note 5, "Revenue Recognition," for additional disclosures relating to ASC 606. In February 2016, the FASB issued ASU 2016-02, “Leases (ASC 842),” which requires lessees to recognize a right-of-use asset and lease liability for all leases with a term of more than 12 months. ASU 2016-02 is effective for us on October 1, 2019, and requires a modified retrospective application. In July 2018, the FASB issued ASU 2018-11, “Leases (ASC 842) Targeted Improvements,” which provides an additional transition method that allows entities to initially apply the new standard at the adoption date and recognize a cumulative effect adjustment to the opening balance of retained earnings in the period of adoption without restating prior periods. We plan to utilize this transition method upon adoption, and as a result, we will not adjust comparative period financial information or make the new required lease disclosures for periods before the effective date. Our preparation for the adoption of ASC 842 is substantially complete. We have compiled an inventory of our lease agreements in order to determine the impact the new guidance will have on our financial statements and disclosures and have implemented new lease accounting software in preparation for the standard’s additional reporting requirements. We have elected certain practical expedients available under the guidance, including a package of practical expedients which allows us to not reassess prior conclusions related to contracts containing leases, lease classification, and initial direct costs. Based on our assessment to date, we expect that the adoption of ASC 842 will result in the recognition of right-of-use assets and corresponding lease liabilities of approximately 1% of total assets and liabilities, respectively, in our consolidated balance sheet as of October 1, 2019. We do not expect the new standard to have a material impact on our consolidated results of operations and cash flows. In June 2016, the FASB issued ASU 2016-13, "Financial Instruments—Credit Losses: Measurement of Credit Losses on Financial Instruments (ASU 2016-13)," which changes the impairment model for most financial assets. The new model uses a forward-looking expected loss method, which will generally result in earlier recognition of allowances for losses. ASU 2016-13 is effective for the Company for annual and interim periods beginning after October 1, 2020 and early adoption is permitted. The Company is currently evaluating the impact of adopting this standard on our consolidated financial statements and disclosures. In October 2016, the FASB issued ASU 2016-16, “Intra-Entity Transfers of Assets Other Than Inventory” (ASU 2016-16). This accounting standard requires companies to recognize the income tax effects of intercompany sales and transfers of assets, other than inventory, in the period in which the transfer occurs. Under previous guidance companies were required to defer the income tax effects of intercompany transfers of assets by recording prepaid taxes, until such assets were sold to an outside party or otherwise recognized. Current guidance requires companies to write off any income tax amounts previously deferred as prepaid taxes from past intercompany transactions, and to record deferred tax balances for amounts not previously recognized, through a cumulative-effect adjustment to retained earnings. ASU 2016-16 is effective for public business entities for fiscal years beginning after December 15, 2017, including interim periods within those years. The Company adopted this standard in the first quarter of fiscal 2019. The adoption of this standard did not have a material impact on our consolidated financial statements. Refer to the consolidated statements of stockholders' deficit for the impact of the adoption of ASU 2016-16 on retained earnings. In January 2017, the FASB issued ASU 2017-04, “Simplifying the Test for Goodwill Impairment,” to eliminate Step 2 from the goodwill impairment test in order to simplify the subsequent measurement of goodwill. The guidance is effective for the Company for fiscal years beginning after October 1, 2020, with early adoption permitted. The adoption of this standard is not expected to have a material impact on our consolidated financial statements and disclosures. In March 2017, the FASB issued ASU 2017-07, "Compensation—Retirement Benefits (ASC 715): Improving the Presentation of Net Periodic Pension Cost and Net Periodic Postretirement Benefit Cost," that changes how employers that sponsor defined benefit and/or other postretirement benefit plans present the net periodic benefit cost in the income statement. Under previous guidance, companies included all components of the net periodic benefit costs in the same lines as the service cost component. Current guidance requires employers to present the other components of the net periodic benefit costs separately from the line items that include the service cost and outside of any subtotal of operating income. In addition, only the service cost component will be eligible for capitalization in assets. Employers will have to disclose the lines used to present the other components of net periodic benefit cost, if the components are not presented separately in the income statement. The standard is effective for public business entities for fiscal years beginning after December 15, 2017, and interim periods within the fiscal year. The Company adopted this standard in the first quarter of fiscal 2019. The adoption of this standard did not have a material impact on our consolidated financial statements. In May 2017, the FASB issued ASU 2017-09, "Compensation—Stock Compensation (ASC 718): Scope of Modification Accounting," which provides clarity on which changes to the terms or conditions of share-based payment awards require an entity to apply the modification accounting provisions required in ASC 718. The standard is effective for all entities for annual periods beginning after December 15, 2017, with early adoption permitted, including adoption in any interim period for which financial statements have not yet been issued. The Company adopted this standard in the first quarter of fiscal 2019. The adoption of this standard did not have a material impact on our consolidated financial statements. In February 2018, the FASB issued ASU 2018-02, "Income Statement - Reporting Comprehensive Income (ASC 220): Reclassification of Certain Tax Effects from Accumulated Other Comprehensive Income," which gives entities the option to reclassify tax effects stranded in accumulated other comprehensive income as a result of the Tax Cuts and Jobs Act (the "Act") into retained earnings. The guidance allows entities to reclassify from accumulated other comprehensive income to retained earnings stranded tax effects resulting from the Act's new federal corporate income tax rate. The guidance also allows entities to elect to reclassify other stranded tax effects that relate to the Act but do not directly relate to the change in the federal tax rate (e.g., state taxes, changing from a worldwide tax system to a territorial system). Tax effects that are stranded in accumulated other comprehensive income for other reasons (e.g., prior changes in tax law, a change in valuation allowance) may not be reclassified. The standard is effective for the Company for fiscal years beginning after October 1, 2019, and interim periods within the fiscal year. Early adoption is permitted, including adoption in any interim period for which financial statements have not yet been issued. Entities have the option to apply the guidance retrospectively or in the period of adoption. As early adoption is permissible, the Company adopted the pronouncement beginning October 1, 2018. Changes were applied in the period of adoption and prior periods were not adjusted.The adoption of this standard did not have a material impact on our consolidated financial statements. In August 2018, the FASB issued ASU 2018-14, "Compensation - Retirement Benefits - Defined Benefit Plans - General (ASC 715-20)." ASU 2018-14 modifies disclosure requirements for employers that sponsor defined benefit pension or other postretirement plans. The ASU also requires an entity to disclose the weighted-average interest crediting rates for cash balance plans and to explain the reasons for significant gains and losses related to changes in the benefit obligation. The ASU is effective for the Company on October 1, 2020 and early adoption is permitted. The Company is currently evaluating the impact of adopting this standard on our consolidated financial statements and disclosures.

REVENUE RECOGNITION (Notes)

REVENUE RECOGNITION (Notes)	12 Months Ended
	Sep. 30, 2019
Revenue Recognition [Abstract]
Revenue from Contract with Customer [Text Block]	REVENUE RECOGNITION The Company’s sales are concentrated in the aerospace industry. TransDigm’s customers include: distributors of aerospace components; commercial airlines, large commercial transport and regional and business aircraft OEMs; various armed forces of the United States and friendly foreign governments; defense OEMs; system suppliers; and various other industrial customers. In 2019 , one customer accounted for approximately 11% of the Company’s net sales for the fiscal year ended 2019. Sales to this customer was split approximately 60% and 40% between the Airframe and Power & Control segments, respectively. No other customer individually accounted for more than 10% of the Company’s net sales. In 2018 and 2017 , two customers individually accounted for more than 10% of the Company’s net sales. One customer accounted for approximately 11% and 13% of the Company’s net sales for fiscal years ended 2018 and 2017, respectively. The second customer accounted for approximately 10% and 11% of the Company’s net sales for fiscal years ended 2018 and 2017 , respectively. Sales to these customers were split approximately evenly between the Power & Control and Airframe segments. Sales to foreign customers, primarily in Western Europe, Canada and Asia, were $1,778.4 million , $1,355.1 million and $1,318.9 million during the fiscal years ended 2019 , 2018 and 2017 . Adoption of ASC 606, “Revenue from Contracts with Customers” The Company adopted ASC 606, “Revenue from Contracts with Customers,” beginning October 1, 2018 using the modified retrospective method. The new standard primarily impacted the Company's timing of revenue recognition for certain contracts and subcontracts with the U.S. government that contain termination for convenience clauses and for which the product being produced has no alternative use, and resulted in an increase to retained earnings of $3.3 million . The comparative information has not been restated and continues to be reported under the accounting standards in effect for those periods. The cumulative effect of the changes made to our consolidated balance sheet as of October 1, 2018 for the adoption of ASC 606 were as follows (in thousands): September 30, 2018 Adjustments due to ASC 606 October 1, 2018 Assets Unbilled receivables (1) $ 10,056 $ 8,272 $ 18,328 Inventories - Net 805,292 (3,977 ) 801,315 Liabilities and Stockholders' Deficit Deferred income taxes $ 399,496 $ 1,011 $ 400,507 Accumulated deficit (2,246,578 ) 3,284 (2,243,294 ) (1) Included in prepaid expenses and other on the consolidated balance sheet. Revenue is recognized from the sale of products when control transfers to the customer, which is demonstrated by our right to payment, a transfer of title, a transfer of the risk and rewards of ownership, or the customer acceptance, but most frequently upon shipment where the customer obtains physical possession of the goods. The majority of the Company's revenue is recorded at a point in time. In certain contracts the Company found that under ASC 606, control transferred to the customer over time primarily in contracts where the customer is required to pay for the cost of both the finished and unfinished goods at the time of cancellation plus a reasonable profit relative to the work performed for products that were customized for the customer. Upon adoption of ASC 606, we recognize revenue over time for those agreements that have a right to margin and where the products being produced have no alternative use. Prior to the adoption date, revenue related to these agreements was recognized when the goods were shipped; as a result of the adoption of ASC 606, a portion of our revenue may be earned in periods earlier than it would have been in prior years. The cumulative adjustment to retained earnings upon adoption, which is presented in the table above, represents those earnings that would have been recognized in the previous year had ASC 606 been in effect during that time. Based on our production cycle, it is generally expected that goods related to the revenue represented in that adjustment will be shipped and billed within the current year. For revenue recognized over time, we estimate the amount of revenue attributable to a contract earned at a given point during the production cycle based on certain costs, such as materials and labor incurred to date, plus the expected profit, which is a cost-to-cost input method. The Company’s payment terms vary by the type and location of the customer and the products or services offered. The Company does not offer any payment terms that would meet the requirements for consideration as a significant financing component under ASC 606. Shipping and handling fees and costs incurred in connection with products sold are recorded in cost of sales in the consolidated statements of income, and are not considered a performance obligation to our customers. Contract Assets and Liabilities —Contract assets reflect revenue recognized and performance obligations satisfied in advance of customer billing or reimbursable costs related to a specific contract. Contract liabilities relate to payments received in advance of the satisfaction of performance under the contract. We receive payments from customers based on the terms established in our contracts. The following table summarizes our contract assets and liabilities balances (in thousands): September 30, 2019 October 1, 2018 Change Contract assets, current (1) $ 44,097 $ 18,328 $ 25,769 Contract assets, non-current (2) 7,238 118 7,120 Total contract assets 51,335 18,446 32,889 Contract liabilities, current (3) 17,840 2,742 15,098 Contract liabilities, non-current (4) 13,234 — 13,234 Total contract liabilities 31,074 2,742 28,332 Net contract assets $ 20,261 $ 15,704 $ 4,557 (1) Included in prepaid expenses and other on the consolidated balance sheet. (2) Included in other non-current assets on the consolidated balance sheet. (3) Included in accrued liabilities on the consolidated balance sheet. (4) Included in other non-current liabilities on the consolidated balance sheet. Changes in the contract asset and liability balances during the fiscal year ended September 30, 2019 were not materially impacted by any factors other than the Esterline acquisition. For the fiscal year ended September 30, 2019 , the revenue recognized that was previously included in the beginning balance of contract liabilities was immaterial. Refer to Note 17, “Segments,” for disclosures related to the disaggregation of revenue.

EARNINGS PER SHARE

EARNINGS PER SHARE	12 Months Ended
	Sep. 30, 2019
Earnings Per Share [Abstract]
EARNINGS PER SHARE (TWO-CLASS METHOD)	EARNINGS PER SHARE The following table sets forth the computation of basic and diluted earnings per share (in thousands, except per share data) using the two-class method: Fiscal Years Ended September 30, 2019 2018 2017 Numerator for earnings per share: Income from continuing operations including noncontrolling interests $ 840,879 $ 961,536 $ 628,541 Net income attributable to noncontrolling interests (1,541 ) — — Net income from continuing operations attributable to TD Group 839,338 961,536 628,541 Less dividends paid on participating securities (111,021 ) (56,148 ) (159,257 ) 728,317 905,388 469,284 Income (loss) from discontinued operations, net of tax 50,432 (4,474 ) (31,654 ) Net income applicable to TD Group common stock—basic and diluted $ 778,749 $ 900,914 $ 437,630 Denominator for basic and diluted earnings per share under the two-class method: Weighted-average common shares outstanding 53,091 52,345 52,517 Vested options deemed participating securities 3,174 3,252 3,013 Total shares for basic and diluted earnings per share 56,265 55,597 55,530 Net earnings per share from continuing operations—basic and diluted $ 12.94 $ 16.28 $ 8.45 Net earnings (loss) per share from discontinued operations—basic and diluted 0.90 (0.08 ) (0.57 ) Net earnings per share $ 13.84 $ 16.20 $ 7.88

TRADE ACCOUNTS RECEIVABLE

TRADE ACCOUNTS RECEIVABLE	12 Months Ended
	Sep. 30, 2019
Receivables [Abstract]
SALES AND TRADE ACCOUNTS RECEIVABLE	TRADE ACCOUNTS RECEIVABLE Trade accounts receivable consist of the following (in thousands): September 30, 2019 September 30, 2018 Trade accounts receivable—gross $ 1,085,005 $ 708,984 Allowance for uncollectible accounts (17,402 ) (4,674 ) Trade accounts receivable—net $ 1,067,603 $ 704,310 At September 30, 2019 , approximately 20% of the Company’s trade accounts receivable was due from two customers. One customer accounted for approximately 13% percent of the Company’s trade accounts receivable and the other customer accounted for approximately 7% of the Company’s trade accounts receivable. In addition, approximately 36%

INVENTORIES

INVENTORIES	12 Months Ended
	Sep. 30, 2019
Inventory Disclosure [Abstract]
INVENTORIES	INVENTORIES Inventories consist of the following (in thousands): September 30, 2019 September 30, 2018 Raw materials and purchased component parts $ 804,687 $ 540,290 Work-in-progress 360,230 237,335 Finished goods 191,535 127,018 Total 1,356,452 904,643 Reserves for excess and obsolete inventory (123,803 ) (99,351 ) Inventories—Net $ 1,232,649 $ 805,292

PROPERTY, PLANT AND EQUIPMENT

PROPERTY, PLANT AND EQUIPMENT	12 Months Ended
	Sep. 30, 2019
Property, Plant and Equipment [Abstract]
PROPERTY, PLANT AND EQUIPMENT	PROPERTY, PLANT AND EQUIPMENT Property, plant and equipment consist of the following (in thousands): September 30, 2019 September 30, 2018 Land and improvements $ 95,536 $ 77,455 Buildings and improvements 407,461 171,269 Machinery, equipment and other 628,096 448,014 Construction in progress 52,241 31,237 Total 1,183,334 727,975 Accumulated depreciation (426,577 ) (339,642 ) Property, plant and equipment—net $ 756,757 $ 388,333

INTANGIBLE ASSETS

INTANGIBLE ASSETS	12 Months Ended
	Sep. 30, 2019
Goodwill and Intangible Assets Disclosure [Abstract]
INTANGIBLE ASSETS	INTANGIBLE ASSETS Other intangible assets - net in the consolidated balance sheets consist of the following at September 30 (in thousands): 2019 2018 Gross Carrying Amount Accumulated Amortization Net Gross Carrying Amount Accumulated Amortization Net Trademarks and trade names $ 956,377 $ — $ 956,377 $ 799,749 $ — $ 799,749 Technology 1,805,715 496,311 1,309,404 1,347,314 416,579 930,735 Order backlog 106,889 44,603 62,286 12,200 5,409 6,791 Customer relationships 437,973 29,777 408,196 62,561 14,277 48,284 Other 16,707 9,150 7,557 10,873 8,028 2,845 Total $ 3,323,661 $ 579,841 $ 2,743,820 $ 2,232,697 $ 444,293 $ 1,788,404 Information regarding the amortization expense of amortizable intangible assets is detailed below (in thousands): Annual Amortization Expense: Years ended September 30, 2019 $ 134,952 2018 72,454 2017 89,226 Estimated Amortization Expense: Years ending September 30, 2020 $ 182,583 2021 119,067 2022 119,067 2023 119,067 2024 119,067 As disclosed in Note 2, "Acquisitions and Divestitures," the estimated fair value of the net identifiable tangible and intangible assets acquired from Esterline are based on the acquisition method of accounting and are subject to adjustment upon completion of the third-party valuation appraisals. Material adjustments may occur. The fair value of the net identifiable tangible and intangible assets acquired will be finalized within the allowable one year measurement period. Intangible assets acquired during fiscal year ended September 30, 2019 are summarized in the table below (in thousands): Gross Amount Amortization Period Intangible assets not subject to amortization: Goodwill $ 2,194,324 Trademarks and trade names 238,200 2,432,524 Intangible assets subject to amortization: Technology 503,500 20 years Order backlog 99,100 1.5 years Customer relationships 483,935 20 years 1,086,535 18 years Total $ 3,519,059 The changes in the carrying amount of goodwill by segment for the fiscal years ended September 30, 2018 and 2019 were as follows (in thousands): Power & Control Airframe Non- aviation Total Balance at September 30, 2017 $ 3,269,981 $ 2,382,082 $ 93,275 $ 5,745,338 Goodwill acquired during the year (Note 2) 402,540 73,321 — 475,861 Purchase price allocation adjustments 5,354 — — 5,354 Currency translation adjustment — (3,258 ) — (3,258 ) Other (192 ) 187 — (5 ) Balance at September 30, 2018 3,677,683 2,452,332 93,275 6,223,290 Goodwill acquired during the year (Note 2) 468,613 1,179,999 545,712 2,194,324 Divestiture of goodwill acquired during the year — — (42,678 ) (42,678 ) Reclassification of goodwill acquired to assets held-for-sale (Note 23) — — (480,312 ) (480,312 ) Purchase price allocation adjustments (8,690 ) (22,901 ) — (31,591 ) Currency translation adjustment (16,422 ) (11,695 ) (14,813 ) (42,930 ) Balance at September 30, 2019 $ 4,121,184 $ 3,597,735 $ 101,184 $ 7,820,103

ACCRUED LIABILITIES

ACCRUED LIABILITIES	12 Months Ended
	Sep. 30, 2019
Payables and Accruals [Abstract]
ACCRUED LIABILITIES	ACCRUED LIABILITIES Accrued liabilities consist of the following (in thousands): September 30, 2019 September 30, 2018 Compensation and related benefits $ 177,862 $ 81,035 Interest 92,642 96,590 Interest rate swap agreements 13,219 528 Product warranties 33,882 21,056 Dividend equivalent payments—current (see Note 18) 63,796 24,200 Environmental and other litigation reserves 12,016 31,079 Income taxes payable 44,370 9,168 Loss contract reserves 64,665 11,682 Other 173,243 76,105 Total $ 675,695 $ 351,443

DEBT

DEBT	12 Months Ended
	Sep. 30, 2019
Debt Disclosure [Abstract]
DEBT	DEBT The Company’s debt consists of the following (in thousands): September 30, 2019 Gross Amount Debt Issuance Costs Original Issue Discount or Premium Net Amount Short-term borrowings—trade receivable securitization facility $ 350,000 $ (481 ) $ — $ 349,519 Term loans $ 7,523,507 $ (57,744 ) $ (17,214 ) $ 7,448,549 6.00% senior subordinated notes due July 15, 2022 (2022 Notes) 1,150,000 (4,061 ) — 1,145,939 6.50% senior subordinated notes due July 15, 2024 (2024 Notes) 1,200,000 (5,690 ) — 1,194,310 6.50% senior subordinated notes due May 15, 2025 (2025 Notes) 750,000 (2,977 ) 3,090 750,113 6.375% senior subordinated notes due June 15, 2026 (6.375% 2026 Notes) 950,000 (6,790 ) — 943,210 6.875% senior subordinated notes due May 15, 2026 (6.875% 2026 Notes) 500,000 (5,532 ) (3,137 ) 491,331 6.25% secured notes due March 15, 2026 (2026 Secured Notes) 4,000,000 (59,630 ) 1,812 3,942,182 7.50% senior subordinated notes due March 15, 2027 (2027 Notes) 550,000 (5,300 ) — 544,700 Government refundable advances 39,195 — — 39,195 Capital lease obligations 49,905 — — 49,905 16,712,607 (147,724 ) (15,449 ) 16,549,434 Less current portion 80,951 (738 ) — 80,213 Long-term debt $ 16,631,656 $ (146,986 ) $ (15,449 ) $ 16,469,221 September 30, 2018 Gross Amount Debt Issuance Costs Original Issue Discount or Premium Net Amount Short-term borrowings—trade receivable securitization facility $ 300,000 $ (481 ) $ — $ 299,519 Term loans $ 7,599,932 $ (69,697 ) $ (21,030 ) $ 7,509,205 5.50% 2020 Notes 550,000 (2,187 ) — 547,813 6.00% 2022 Notes 1,150,000 (5,501 ) — 1,144,499 6.50% 2024 Notes 1,200,000 (6,866 ) — 1,193,134 6.50% 2025 Notes 750,000 (3,505 ) 3,636 750,131 6.375% 2026 Notes 950,000 (7,798 ) — 942,202 6.875% 2026 Notes 500,000 (5,616 ) (3,605 ) 490,779 12,699,932 (101,170 ) (20,999 ) 12,577,763 Less current portion 76,427 (610 ) — 75,817 Long-term debt $ 12,623,505 $ (100,560 ) $ (20,999 ) $ 12,501,946 Trade Receivable Securitization Facility During fiscal 2014, the Company established a trade receivable securitization facility (the “Securitization Facility”). The Securitization Facility effectively increases the Company’s borrowing capacity depending on the amount of the domestic operations’ trade accounts receivable. The Securitization Facility includes the right for the Company to exercise annual one year extensions as long as there have been no termination events as defined by the agreement. The Company uses the proceeds from the Securitization Facility as an alternative to other forms of debt, effectively reducing borrowing costs. On July 30, 2019, the Company amended the Securitization Facility to extend the maturity date to July 31, 2020. As of September 30, 2019, the Company has borrowed $350 million under the Securitization Facility, which bears interest at a rate of 0.9% plus LIBOR. At September 30, 2019, the applicable interest rate was 2.94% . The Securitization Facility is collateralized by substantially all of the Company’s domestic operations’ trade accounts receivable. Issuance of Senior Secured Notes due 2026 On January 30, 2019, the Company entered into a purchase agreement in connection with a private offering of $3.8 billion aggregate principal amount of 6.25% senior secured notes due 2026. In addition, on February 1, 2019, the Company entered into a purchase agreement in connection with a private offering of $200 million aggregate principal amount of 6.25% senior secured notes due 2026 (herein the "2026 Secured Notes"). All $4.0 billion aggregate principal amount of the 2026 Secured Notes constituted a single class and were issued under a single indenture. The notes in the $3.8 billion secured notes offering were issued at a price of 100% of their principal amount and the notes in the $200 million secured notes offering were issued at a price of 101% of their principal amount. The 2026 Secured Notes are guaranteed, with certain exceptions, by TransDigm Group, TransDigm UK and all of TransDigm Inc.’s existing U.S. subsidiaries on a senior secured basis. The 2026 Secured Notes bear interest at a rate of 6.25% per annum, which accrues from February 13, 2019 and is payable semiannually in arrears on March 15th and September 15th of each year, commencing on September 15, 2019. The 2026 Secured Notes mature on March 15, 2026, unless earlier redeemed or repurchased, and are subject to the terms and conditions set forth in the Secured Notes Indenture. In addition to the premium of $2.0 million capitalized upon the issuance of the $200 million issuance of the 2026 Senior Notes, the Company capitalized $65.6 million and expensed $0.8 million of debt issuance costs associated with the issuance of the 2026 Senior Secured Notes during the fiscal year ended September 30, 2019 . Issuance of Senior Subordinated Notes due 2027 On February 1, 2019, the Company entered into a purchase agreement in connection with a private offering of $550 million in new 7.50% senior subordinated notes due 2027 (herein the "2027 Notes"). The 2027 Notes were issued pursuant to an indenture, dated as of February 13, 2019, among TransDigm, as issuer, TD Group, TD UK and the other subsidiaries of TransDigm named therein, as guarantors, and The Bank of New York Mellon Trust Company, N.A., as trustee. The 2027 Notes bear interest at the rate of 7.50% per annum, which accrues from February 13, 2019 and is payable in arrears on March 15th and September 15th of each year, commencing on September 15, 2019. The 2027 Notes mature on March 15, 2027, unless earlier redeemed or repurchased, and are subject to the terms and conditions set forth in the indenture. The Company capitalized $5.8 million of debt issuance costs associated with the 2027 Notes during the fiscal year ended September 30, 2019 . Repurchase of Senior Subordinated Notes due 2020 On February 13, 2019, the Company announced a cash tender offer for any and all of its 2020 Notes outstanding. On March 15, 2019, the Company redeemed the principal amount of $550 million , plus accrued interest of approximately $12.6 million . The Company wrote off $1.7 million in unamortized debt issuance costs during the fiscal year ended September 30, 2019 in conjunction with the redemption of the 2020 Notes. Amendment No. 6 to the Second Amended and Restated Credit Agreement On March 14, 2019, the Company entered into Amendment No. 6 to the Second Amended and Restated Credit Agreement (herein, "Amendment No. 6"). Under the terms of Amendment No. 6, certain existing lenders increased the revolving commitments, including $52.1 million in multicurrency revolving commitments, in an aggregate principal amount of $160 million , to a total revolving commitments capacity of $760 million . The revolving commitments consist of two tranches which include up to $151.5 million of multicurrency revolving commitments. The terms and conditions that apply to the revolving credit facility, other than the additional revolving credit commitments, are substantially the same as the terms and conditions that applied to the revolving credit facility immediately prior to Amendment No. 6. At September 30, 2019 , the Company had $41.5 million in letters of credit outstanding, and $718.5 million of borrowings available under the revolving commitments, subject to restrictions under existing debt covenants. The Company utilizes letters of credit to back certain payment and performance obligations. Government Refundable Advances Government refundable advances consist of payments received from the Canadian government to assist in research and development related to commercial aviation. The requirement to repay this advance is solely based on year-over-year commercial aviation revenue growth at CMC Electronics, which is a subsidiary of TransDigm (acquired via the Esterline acquisition). These obligations were assumed in connection with the Esterline acquisition and the balance was $39.2 million at September 30, 2019 . Obligations under Capital Leases The Company leases certain buildings and equipment under capital leases. These obligations were assumed in connection with the Esterline acquisition and the present value of the minimum capital lease payments, net of the current portion, was a balance of $49.9 million at September 30, 2019 . Term Loans As of September 30, 2019 and 2018 , TransDigm had $7,523.5 million and $7,599.9 million in fully drawn term loans and $760 million and $600 million in revolving commitments. The term loans consist of three tranches as follows (in millions): Term Loan Facility Maturity Date Interest Rate Aggregate Principal as of September 30, 2019 2018 Tranche E May 30, 2025 LIBO rate + 2.5% $ 2,221.2 $ 2,243.7 Tranche F June 9, 2023 LIBO rate + 2.5% $ 3,524.1 $ 3,559.9 Tranche G August 22, 2024 LIBO rate + 2.5% $ 1,778.2 $ 1,796.3 The interest rates per annum applicable to all of the existing tranches of term loans are, at TransDigm’s option, equal to either an alternate base rate or an adjusted LIBO rate for one, two, three or six-month (or to the extent agreed to by each relevant lender, nine or twelve-month) interest periods chosen by TransDigm, in each case plus an applicable margin percentage. The adjusted LIBO rate is not subject to a floor. At September 30, 2019 and 2018 , the applicable interest rates for all existing tranches were 4.83% and 4.58% , respectively. Debt Issuance Costs, Premiums and Discounts During the fiscal year ended September 30, 2019 , the Company recorded refinancing costs of $3.0 million representing the repurchase of the $550 million 2020 Senior Subordinated Notes and issuance of the $4.0 billion 2026 Senior Secured Notes. During the fiscal year ended September 30, 2018 , the Company recorded refinancing costs of $6.4 million representing the refinancing of tranche D, E, F & G term loans, and issuance of the $500 million 6.875% Senior Subordinated Notes. During the fiscal year ended September 30, 2017 , the Company recorded refinancing costs of $39.8 million representing debt issuance costs and premium expensed in conjunction with the new tranche G term loans, the refinancing of the tranche C term loans, and additional $300 million tack-on to the 6.375% Notes. Interest Rate Swap and Cap Agreements See Note 21, “Derivatives and Hedging Activities,” for information about how our interest rate swap and cap agreements are used to manage interest rate risk associated with floating-rate borrowings under our credit facilities. Senior Subordinated Notes The Notes are subordinated to all of TransDigm’s existing and future senior debt, rank equally with all of its existing and future senior subordinated debt and rank senior to all of its future debt that is expressly subordinated to the Notes. The Notes are guaranteed on a senior subordinated unsecured basis by TD Group and its 100% -owned domestic subsidiaries named in the indentures. The guarantees of the Notes are subordinated to all of the guarantors’ existing and future senior debt, rank equally with all of their existing and future senior subordinated debt and rank senior to all of their future debt that is expressly subordinated to the guarantees of the Notes. See Note 27, “Supplemental Guarantor Information,” for further details. The Notes are structurally subordinated to all of the liabilities of TD Group’s non-guarantor subsidiaries. The Notes contain many of the restrictive covenants included in the Restated Credit Agreement. TransDigm is in compliance with all the covenants contained in the Notes. At September 30, 2019 , future maturities of long-term debt are as follows (in thousands): Fiscal years ended September 30, 2020 $ 80,951 2021 81,979 2022 (1) 1,232,200 2023 3,462,528 2024 2,933,675 Thereafter 8,921,274 $ 16,712,607 (1) On October 29, 2019, the Company entered into a purchase agreement in connection with a private offering of $2.65 billion aggregate principal amount in 5.50% senior subordinated notes in which part of the proceeds will be used to repurchase its 2022 Notes in the first quarter of fiscal 2020. Refer to Note 26, “Subsequent Events” to our consolidated financial statements included herein for further details. Subsequent Event - Cash Tender and Redemption of 2022 Notes On October 29, 2019, the Company entered into a purchase agreement in connection with a private offering of $2.65 billion aggregate principal amount in 5.50% senior subordinated notes due November 15, 2027. The settlement of the debt financing transaction occurred on November 13, 2019. The notes were issued at a price of 100% of their principal amount. The Company will use a portion of the net proceeds from the offering of the notes to cash tender and redeem all of its outstanding (aggregate principal amount of $1.15 billion

RETIREMENT PLANS

RETIREMENT PLANS	12 Months Ended
	Sep. 30, 2019
Retirement Benefits [Abstract]
RETIREMENT PLANS	RETIREMENT PLANS The Company maintains certain non-contributory defined benefit pension plans. The plans provide benefits of stated amounts for each year of service. The Company’s funding policy is to contribute actuarially determined amounts allowable under tax and statutory regulations for the qualified plans. The Company uses a September 30th measurement date for its defined benefit pension plans. In addition, the Company makes actuarially computed contributions to these plans as necessary to adequately fund benefits. The Company’s funding policy is consistent with the minimum funding requirements of ERISA. As part of the Esterline acquisition, the Company acquired the Esterline defined benefit plan that covers certain U.S. employees. Refer to Note 2, “Acquisitions and Divestitures,” for further discussion of the Esterline acquisition. Under the Esterline defined benefit plan, pension benefits are earned under a cash balance formula with annual pay credits ranging from 2% to 6% effective January 1, 2003. Prior to 2003, pension benefits are based on years of service and five-year average compensation for the highest five consecutive years’ compensation during the last ten years of employment. Participants elected either to continue earning benefits under the prior plan formula or to earn benefits under the cash balance formula. Effective January 1, 2003, all new participants were enrolled in the cash balance formula. Additionally, as part of the Esterline acquisition, the Company acquired an unfunded supplemental retirement plan for key Esterline executives providing for periodic payments upon retirement. The Company also sponsors other retirement benefit plans for certain employees in the U.S. Other retirement benefit plans are non-contributory health care and life insurance plans. The Company sponsors a number of non-U.S. defined benefit pension plans primarily in Canada, Belgium, France, Germany and the United Kingdom. These defined benefit plans generally provide benefits to employees based on formulas recognizing length of service and earnings. The Company also sponsors other retirement benefit plans for its employees in Canada. Other retirement benefit plans are non-contributory health care and life insurance plans. The accumulated benefit obligation and projected benefit obligation for the U.S. plans are $365.6 million and $378.8 million , respectively, with plan assets of $317.9 million as of September 30, 2019. The underfunded status for the Company’s U.S. plans is $61.0 million at September 30, 2019, of which $22.1 million is for the acquired unfunded supplemental retirement plan for the former Esterline key executives. Contributions to the Company’s qualified and non-qualified U.S. plans totaled $1.4 million and $0.9 million , respectively, in fiscal 2019. Contributions to the Company’s qualified U.S. plans totaled $1.6 million in fiscal 2018. The Company had no unqualified U.S. plans in fiscal 2018. There is an expected funding requirement of $0.7 million for fiscal 2020 for the qualified U.S. pension plans maintained by the Company. The accumulated benefit obligation and projected benefit obligation for the non-U.S. plans are $258.2 million and $270.0 million , respectively, with plan assets of $233.6 million as of September 30, 2019. The underfunded status for these non-U.S. plans is $36.4 million at September 30, 2019. Contributions to the non-U.S. plans totaled $2.7 million and $1.0 million in fiscal 2019 and 2018, respectively. The expected funding requirement for fiscal 2020 for the non-U.S. plans is $5.3 million . U.S. Defined Benefit Pension Plans Non-U.S. Defined Benefit Pension Plans Principal assumptions as of year end: 2019 2018 2019 2018 Discount rate 3.03% 3.96% 2.20% 2.68% Rate of increase in future compensation levels 4.48% N/A 2.98% 3.22% Assumed long-term rate of return on plan assets 6.00% 6.50% 4.16% 4.3% U.S. Post-Retirement Pension Plans Non-U.S. Post Retirement Pension Plans Principal assumptions as of year end: 2019 2018 2019 2018 Discount rate 2.86% 3.99% 2.68% N/A Initial weighted average health care trend rate 7.46% 8.50% 5.60% N/A Ultimate weighted average health care trend rate 6.00% 6.00% 4.10% N/A The Company uses discount rates developed from a yield curve established from high-quality corporate bonds and matched to plan-specific projected benefit payments. Although future changes to the discount rate are unknown, had the discount rate increased or decreased by 25 basis points, pension liabilities in total would have decreased $19.2 million or increased $20.3 million , respectively. Had the discount rate increased or decreased by 25 basis points, fiscal 2019 net periodic benefit cost for the pension plans would have remained approximately the same or decreased $0.1 million , respectively. In determining the expected long-term rate of return on the defined benefit pension plans’ assets, the Company considers the historical rates of return, the nature of investments, the asset allocation, and expectations of future investment strategies. Had the expected return on assets increased or decreased by 25 basis points, fiscal 2019 net periodic benefit cost would have decreased $0.8 million or increased $0.8 million , respectively. Management is not aware of any legislative or other initiatives or circumstances that will significantly impact the Company’s pension obligations in fiscal 2020. The Company’s health care trend rate was based on the experience of its plans and expectations for the future. A 100 basis points increase in the health care trend rate would increase the post-retirement benefit obligation by $1.5 million . A 100 basis points decrease in the health care trend rate would decrease the post-retirement benefit obligation by $1.3 million . Assuming all other assumptions are held constant, the estimated effect on fiscal 2019 post-retirement benefit expense from a hypothetical 100 basis points increase or decrease in the health care trend rate would not have a material effect on our post-retirement benefit expense. Plan assets are invested in a diversified portfolio of equity and debt securities consisting primarily of common stocks, bonds and government securities. The objective of these investments is to maintain sufficient liquidity to fund current benefit payments and achieve targeted risk-adjusted returns. Management periodically reviews allocations of plan assets by investment type and evaluates external sources of information regarding the long-term historical returns and expected future returns for each investment type. Allocations by investment type are as follows : Actual Plan assets allocation as of fiscal year end: Target 2019 2018 Equity securities 35 - 70% 35.1% 27.1% Debt securities 30 - 65% 59.5% 72.5% Cash —% 5.4% 0.4% Total 100.0% 100.0% The following table presents the fair value of the Company’s pension plan assets as of September 30, 2019 , by asset category segregated by level within the fair value hierarchy, as described in Note 20, “Fair Value Measurements” (in thousands): Fair Value Hierarchy Level 1 Level 2 Total Investments measured at fair value by category: Equity Funds: (1) U.S. Equity Securities $ 3,472 $ — $ 3,472 Non-U.S. Equity Securities 47,903 — 47,903 Fixed Income Securities: (2) Non-U.S. Foreign Commercial and Government Bonds — 86,281 86,281 Cash and Cash Equivalents (3) 29,588 — 29,588 $ 80,963 $ 86,281 $ 167,244 Investments measured at net asset value by category: (4) Equity Funds: (1) Commingled Trust Funds - Non-U.S. Securities 142,132 Fixed Income Securities: (2) U.S. Government Bonds and Securities 86,214 U.S Corporate Bonds 108,135 Non-U.S. Corporate Bonds 17,449 Non-U.S. Foreign Commercial and Government Bonds 30,330 Total $ 551,504 The following table presents the fair value of the Company’s pension plan assets as of September 30, 2018 , by asset category segregated by level within the fair value hierarchy, as described in Note 20, “Fair Value Measurements” (in thousands): Fair Value Hierarchy Level 1 Level 2 Total Investments measured at fair value by category: Equity Funds: (1) U.S. Equity Securities $ 3,545 $ — $ 3,545 Non-U.S. Equity Securities 4,959 — 4,959 Cash and Cash Equivalents (3) 295 — 295 $ 8,799 $ — $ 8,799 Investments measured at net asset value by category: (4) Equity Funds: (1) Commingled Trust Funds - Non-U.S. Securities 10,056 Fixed Income Securities: (2) U.S Corporate Bonds 3,710 Non-U.S. Corporate Bonds 16,759 Non-U.S. Foreign Commercial and Government Bonds 29,131 Total $ 68,455 (1) Level 1 Equity Securities are actively traded on U.S. and non-U.S. exchanges and are either valued using the market approach at quoted market prices on the measurement date or at the net asset value of the shares held by the plan on the measurement date based on quoted market prices. (2) Level 2 fixed income securities are primarily valued using the market approach at either quoted market prices, pricing models that use observable market data, or bids provided by independent investment brokerage firms. (3) Cash and cash equivalents include cash which is used to pay benefits and cash invested in a short-term investment fund that holds securities with values based on quoted market prices, but for which the funds are not valued on quoted market basis. (4) These investments are valued at the net asset value (“NAV”) of units held. The NAV is used to estimated fair value and is based on the fair value of the underlying investments held by the fund less its liability. Net periodic pension cost for the Company’s defined benefit plans at the end of each fiscal year consisted of the following (in thousands): Defined Benefit Pension Plans 2019 2018 2017 U.S. Pension Plans Non-U.S. Pension Plans U.S. Pension Plans Non-U.S. Pension Plans U.S. Pension Plans Non-U.S. Pension Plans Components of Net Periodic Cost Service cost $ 4,486 $ 3,486 $ 293 $ 545 $ 304 $ 760 Interest cost 7,434 4,806 778 1,798 1,064 1,721 Expected return on plan assets (10,339 ) (6,267 ) (517 ) (2,334 ) (463 ) (2,550 ) Settlements — 70 — — — — Amortization of prior service cost 62 14 36 — — — Amortization of actuarial loss (gain) 337 221 226 559 630 1,196 Amortization of transition obligation — — 209 — 314 — Net periodic cost (benefit) $ 1,980 $ 2,330 $ 1,025 $ 568 $ 1,849 $ 1,127 Post-Retirement Pension Plans 2019 2018 2017 U.S. Pension Plans Non-U.S. Pension Plans U.S. Pension Plans Non-U.S. Pension Plans U.S. Pension Plans Non-U.S. Pension Plans Components of Net Periodic Cost Service cost $ 5 $ 208 $ 5 $ — $ 5 $ — Interest cost 40 227 31 — 42 — Expected return on plan assets — — — — — — Settlements — — — — — — Amortization of prior service cost 24 — 12 — — — Amortization of actuarial (gain) loss (53 ) — (42 ) — (117 ) — Net periodic cost (benefit) $ 16 $ 435 $ 6 $ — $ (70 ) $ — The funded status of the defined benefit pension and post-retirement plans at the end of fiscal 2019 and 2018 were as follows (in thousands): Defined Benefit Pension Plans Post-Retirement Pension Plans September 30, 2019 September 30, 2018 September 30, 2019 September 30, 2018 U.S. Pension Plans Non-U.S. Pension Plans U.S. Pension Plans Non-U.S. Pension Plans U.S. Pension Plans Non-U.S. Pension Plans U.S. Pension Plans Non-U.S. Pension Plans Benefit Obligations Beginning balance $ 18,683 $ 72,540 $ 19,966 $ 79,495 $ 957 $ — $ 1,002 $ — Currency translation adjustment — (3,973 ) — (1,981 ) — 138 — — Service cost 4,486 3,486 277 578 5 208 5 — Interest cost 7,434 4,806 666 1,821 40 227 31 — Plan participant contributions — 380 — 60 — — — — Actuarial (gain) loss 43,368 28,127 (660 ) (5,387 ) 176 1,058 (136 ) — Acquisitions 318,161 171,377 — — 196 12,459 — — Other adjustments 440 505 — — — — 111 — Benefits paid (13,726 ) (7,239 ) (1,566 ) (2,046 ) (90 ) (315 ) (56 ) — Ending balance $ 378,846 $ 270,009 $ 18,683 $ 72,540 $ 1,284 $ 13,775 $ 957 $ — Plan Assets - Fair Value Beginning balance $ 8,655 $ 59,800 $ 8,006 $ 61,884 $ — $ — $ — $ — Currency translation adjustment — (2,719 ) — (1,572 ) — — — — Realized and unrealized gain (loss) on plan assets 30,743 18,854 582 425 — — — — Plan participants contributions — 380 — 60 — — — — Company contributions 2,300 2,726 1,633 1,049 90 315 56 — Acquisitions 289,944 162,015 — — — — — — Other adjustments — (209 ) — — — — — — Expenses paid (20 ) — — — — — — — Benefits paid (13,726 ) (7,239 ) (1,566 ) (2,046 ) (90 ) (315 ) (56 ) — Ending balance $ 317,896 $ 233,608 $ 8,655 $ 59,800 $ — $ — $ — $ — Funded Status Fair value of plan assets $ 317,896 $ 233,608 $ 8,655 $ 59,800 $ — $ — $ — $ — Benefit obligations (378,846 ) (270,009 ) (18,683 ) (72,540 ) (1,284 ) (13,775 ) (957 ) — Net amount recognized $ (60,950 ) $ (36,401 ) $ (10,028 ) $ (12,740 ) $ (1,284 ) $ (13,775 ) $ (957 ) $ — Amount Recognized on Consolidated Balance Sheet Non-current asset $ — $ 3,639 $ — $ — $ — $ — $ — $ — Current liability (2,460 ) (482 ) (841 ) (254 ) (154 ) (714 ) (88 ) — Non-current liability (58,490 ) (39,558 ) (9,187 ) (12,486 ) (1,130 ) (13,061 ) (869 ) — Net amount recognized $ (60,950 ) $ (36,401 ) $ (10,028 ) $ (12,740 ) $ (1,284 ) $ (13,775 ) $ (957 ) $ — Amounts Recognized in Accumulated Other Comprehensive Income Net actuarial loss (gain) $ 27,809 $ 23,533 $ 5,183 $ 9,416 $ (388 ) $ 1,060 $ (617 ) $ — Prior service cost 766 875 368 185 192 — 216 — Ending balance $ 28,575 $ 24,408 $ 5,551 $ 9,601 $ (196 ) $ 1,060 $ (401 ) $ — The accumulated benefit obligation for all pension plans was $623.8 million at September 30, 2019 and $89.9 million at September 30, 2018 . During fiscal year 2020, the Company expects to recognize amortization of net actuarial losses and prior service credit of $1.5 million and $0.2 million , respectively, in net periodic benefit cost. Estimated future benefit payments expected to be paid from the pension and post-retirement benefit plans or from the Company’s assets are as follows (in thousands): Fiscal Year 2020 $ 34,275 2021 34,700 2022 35,697 2023 37,305 2024 38,059 2025 - 2029 201,998 Defined Contribution Plans The Company sponsors certain defined contribution employee savings plans that cover substantially all of the Company’s employees. Under certain plans, the Company contributes a percentage of employee compensation and matches a portion of employee contributions. The cost recognized for such contributions for the fiscal years ended September 30, 2019 , 2018 and 2017 was approximately $24.5 million , $14.9 million and $14.6 million , respectively.

INCOME TAXES

INCOME TAXES	12 Months Ended
	Sep. 30, 2019
Income Tax Disclosure [Abstract]
INCOME TAXES	INCOME TAXES The Company’s income from continuing operations before income taxes includes the following components for the periods shown below (in thousands): Fiscal Years Ended September 30, 2019 2018 2017 United States $ 877,949 $ 826,539 $ 698,201 Foreign 184,916 159,018 139,229 $ 1,062,865 $ 985,557 $ 837,430 The Company’s income tax provision on income from continuing operations consists of the following for the periods shown below (in thousands): Fiscal Years Ended September 30, 2019 2018 2017 Current Federal $ 153,704 $ 136,651 $ 179,884 State 14,911 11,771 8,596 Foreign 53,720 27,239 21,327 222,335 175,661 209,807 Deferred (349 ) (151,640 ) (918 ) $ 221,986 $ 24,021 $ 208,889 The differences between the income tax provision on income from continuing operations at the federal statutory income tax rate and the tax provision shown in the accompanying consolidated statements of income for the periods shown below are as follows (in thousands): Fiscal Years Ended September 30, 2019 2018 2017 Tax at statutory rate of 21% (24.5% for fiscal 2018 and 35% for fiscal 2017) $ 223,202 $ 241,853 $ 293,129 Stock compensation (57,519 ) (50,796 ) (50,314 ) Domestic manufacturing deduction — (15,091 ) (17,832 ) US tax reform (1) — (146,380 ) — Foreign rate differential 2,136 (13,770 ) (29,685 ) Foreign derived intangible income (15,886 ) — — Foreign tax credits (18,370 ) (2,939 ) — Changes in valuation allowances impacting results (2) 66,101 — — Other—net 22,322 11,144 13,591 Income tax provision $ 221,986 $ 24,021 $ 208,889 (1) On December 22, 2017, the Tax Cuts and Jobs Act (the “Act”) was enacted. The Act reduces the U.S. federal corporate tax rate from 35% to 21% , requires companies to pay a one-time transition tax on earnings from certain foreign subsidiaries that were previously deferred as well as other changes. We recorded tax benefits of $176.4 million related to the remeasurement of our net U.S. deferred tax liabilities to reflect the reduction in the corporate tax rate. We also recorded tax expense of $30.0 million related to the one-time transition tax. (2) Primarily relates to the Company’s business interest expense limitation pursuant to IRC §163(j) as modified by the Act. Such provision, as modified, is effective for the Company beginning in fiscal 2019. In general, the deduction for interest expense is limited to 30% of the sum of the Company’s adjusted taxable income (ATI) and its business interest income. Interest expense disallowed by such limitation, in a taxable year, may be carried forward indefinitely. Based upon available evidence, a valuation allowance was recorded for the resulting carryforward to reflect the Company’s belief that is more likely than not that that such deferred tax asset will not be realized. The components of the deferred taxes consist of the following at September 30 (in thousands): 2019 2018 Deferred tax liabilities: Intangible assets $ (709,561 ) $ (469,939 ) Property, plant and equipment (63,603 ) (26,615 ) Unremitted foreign earnings (7,310 ) (4,488 ) Employee benefits 122,777 73,906 U.S. interest expense limitation 64,968 — Loss contract reserves 62,513 12,670 Net operating losses 58,047 46,487 Interest rate swaps and caps 54,643 (20,052 ) Inventories 39,240 20,916 Non-U.S. income tax credits 23,746 289 U.S. income tax credits 16,850 3,114 Environmental reserves 9,636 8,551 Product warranty reserves 8,394 4,471 Other 11,338 (1,557 ) Total (308,322 ) (352,247 ) Add: Valuation allowance (117,660 ) (47,249 ) Total net deferred tax liabilities $ (425,982 ) $ (399,496 ) At September 30, 2019 , the Company has United Kingdom net operating loss carryforwards of approximately $12.3 million , German net operating loss carryforwards of approximately $14.2 million , Belgium net operating loss carryforwards of $39.5 million , France net operating loss carryforwards of $3.6 million and state net operating loss carryforwards of approximately $1,342.7 million that expire in various years from 2019 to 2039 . The Company had U.S. and non-U.S. tax credit carryforwards of $40.6 million that expire beginning in 2025 . The deferred tax assets for the interest expense limitation, net operating losses, and tax credit carryforwards are reduced by a valuation allowance for the amount of such asset that the Company believes will not be realized. The Company and its subsidiaries file income tax returns in the U.S. federal jurisdiction and various state and local jurisdictions, as well as foreign jurisdictions located in Belgium, Canada, China, France, Germany, Hong Kong, Hungary, India, Israel, Japan, Malaysia, Mexico, Norway, Singapore, Spain, Sri Lanka, Sweden and the United Kingdom. The Company is no longer subject to U.S. federal examinations for years before fiscal 2015.The Company is currently under examination for its federal income taxes in the U.S. for fiscal 2016, in Belgium for fiscal(s) 2016, 2017, and 2018, in Canada for fiscal(s) 2013, 2014, and 2015, and in France for fiscal(s) 2015, 2016, 2017, and 2018. The Company expects the examination to be completed during fiscal 2020. In addition, the Company is subject to state income tax examinations for fiscal years 2009 and later. At September 30, 2018, the Company had not completed its accounting related to the Act. All provisional amounts were based on reasonable estimates using the best information available at the time. During the first quarter of fiscal 2019, the Company completed its accounting related to the Act. Such completion did not have a material impact on the Company’s Consolidated Financial Statements. Other provisions of the Act became effective for the Company in fiscal 2019. The Foreign-Derived Intangible Income (“FDII”) provision effectively applies a lower U.S. tax rate to intangible income derived from serving non-U.S. markets. Conversely, the Global Intangible Low-Taxed Income (“GILTI”) provision requires the Company to subject to U.S. taxation the portion of its earnings, from foreign subsidiaries that exceed an allowable return. The Company has made an accounting policy election to treat GILTI as a current year tax expense in the period in which it is incurred. We, therefore, have not provided for any deferred income tax impacts of GILTI in our consolidated financial statements for the fiscal year ended September 30, 2019. The Act’s one-time repatriation tax and GILTI effectively taxed the undistributed earnings previously deferred from U.S. income taxes. We have provided for foreign withholding taxes in jurisdictions in which we are not considered definitely reinvested, however, such amounts are not significant. A reconciliation of the beginning and ending amount of unrecognized tax benefits is as follows (in thousands): 2019 2018 Balance at October 1 $ 14,080 $ 8,655 Additions based on tax positions related to the prior year 25,936 4,637 Additions based on tax positions related to the current year 422 2,390 Reductions based on tax positions related to the prior year (2,691 ) (100 ) Settlement with tax authorities — (66 ) Lapse in statute of limitations (1,238 ) (1,436 ) Balance at September 30 $ 36,509 $ 14,080 Unrecognized tax benefits at September 30, 2019 and 2018 , the recognition of which would have an effect on the effective tax rate for each fiscal year, amounted to $31.4 million and $ 14.1 million , respectively. The Company classifies all income tax related interest and penalties as income tax expense, which were not significant for the years ended September 30, 2019 and 2018 . As of September 30, 2019 and 2018 , the Company accrued $5.0 million and $1.9 million , respectively, for the potential payment of interest and penalties. The Company anticipates no significant changes to its total unrecognized tax benefits through fiscal 2020.

ENVIRONMENTAL LIABILITIES

ENVIRONMENTAL LIABILITIES	12 Months Ended
	Sep. 30, 2019
Environmental Remediation Obligations [Abstract]
ENVIRONMENTAL LIABILITIES	ENVIRONMENTAL LIABILITIES Our operations and facilities are subject to a number of federal, state, local and foreign environmental laws and regulations that govern, among other things, discharges of pollutants into the air and water, the generation, handling, storage and disposal of hazardous materials and wastes, the remediation of contamination and the health and safety of our employees. Environmental laws and regulations may require that the Company investigate and remediate the effects of the release or disposal of materials at sites associated with past and present operations. Certain facilities and third-party sites utilized by the Company have been identified as potentially responsible parties under the federal superfund laws and comparable state laws. The Company is currently involved in the investigation and remediation of a number of sites under applicable laws. Estimates of the Company’s environmental liabilities are based on current facts, laws, regulations and technology. These estimates take into consideration the Company’s prior experience and professional judgment of the Company’s environmental advisors. Estimates of the Company’s environmental liabilities are further subject to uncertainties regarding the nature and extent of site contamination, the range of remediation alternatives available, evolving remediation standards, imprecise engineering evaluations and cost estimates, the extent of corrective actions that may be required and the number and financial condition of other potentially responsible parties, as well as the extent of their responsibility for the remediation. Accordingly, as investigation and remediation proceed, it is likely that adjustments in the Company’s accruals will be necessary to reflect new information. The amounts of any such adjustments could have a material adverse effect on the Company’s results of operations or cash flows in a given period. Based on currently available information, however, the Company does not believe that future environmental costs in excess of those accrued with respect to sites for which the Company has been identified as a potentially responsible party are likely to have a material adverse effect on the Company’s financial condition. Environmental liabilities are recorded when the liability is probable and the costs are reasonably estimable, which generally is not later than at completion of a feasibility study or when the Company has recommended a remedy or has committed to an appropriate plan of action. The Company also takes into consideration the estimated period of time in which payments will be required. The liabilities are reviewed periodically and, as investigation and remediation proceed, adjustments are made as necessary. Liabilities for losses from environmental remediation obligations do not consider the effects of inflation and anticipated expenditures are not discounted to their present value. The liabilities are not offset by possible recoveries from insurance carriers or other third parties, but do reflect anticipated allocations among potentially responsible parties at federal superfund sites or similar state-managed sites, third party indemnity obligations, and an assessment of the likelihood that such parties will fulfill their obligations at such sites. The Company’s consolidated balance sheets includes current environmental remediation obligations at September 30, 2019 and 2018 of $9.4 million and $7.3 million classified as a component of accrued liabilities, respectively, and non-current environmental remediation obligations at September 30, 2019 and 2018 of $32.7 million and $31.8 million

CAPITAL STOCK

CAPITAL STOCK	12 Months Ended
	Sep. 30, 2019
Equity [Abstract]
CAPITAL STOCK	CAPITAL STOCK TD Group consists of 224,400,000 shares of $.01 par value common stock and 149,600,000 shares of $.01 par value preferred stock. The total number of shares of common stock issued at September 30, 2019 and 2018 was 57,623,311 and 56,895,686 , respectively. The total number of shares held in treasury at September 30, 2019 and 2018 was 4,161,326 . There were no shares of preferred stock outstanding at September 30, 2019 and 2018 . The terms of the preferred stock have not been established. On November 8, 2017, our Board of Directors, authorized a stock repurchase program permitting repurchases of our outstanding shares not to exceed $650 million in the aggregate, subject to any restrictions specified in the Credit Agreement and/or Indentures governing the existing Notes. No repurchases were made under the program during the fiscal years ended September 30, 2019 and 2018. As of September 30, 2019, $650 million

SEGMENTS

SEGMENTS	12 Months Ended
	Sep. 30, 2019
Segment Reporting [Abstract]
SEGMENTS	SEGMENTS The Company’s businesses are organized and managed in three reporting segments: Power & Control, Airframe and Non-aviation. The Power & Control segment includes operations that primarily develop, produce and market systems and components that predominately provide power to or control power of the aircraft utilizing electronic, fluid, power and mechanical motion control technologies. Major product offerings include mechanical/electro-mechanical actuators and controls, ignition systems and engine technology, specialized pumps and valves, power conditioning devices, specialized AC/DC electric motors and generators, databus and power controls, advanced sensor products, switches and relay panels, high performance hoists, winches and lifting devices and cargo loading and handling systems. Primary customers of this segment are engine and power system and subsystem suppliers, airlines, third party maintenance suppliers, military buying agencies and repair depots. Products are sold in the original equipment and aftermarket market channels. The Airframe segment includes operations that primarily develop, produce and market systems and components that are used in non-power airframe applications utilizing airframe and cabin structure technologies. Major product offerings include engineered latching and locking devices, rods and locking devices, engineered connectors and elastomers, cockpit security components and systems, aircraft audio systems, specialized lavatory components, seat belts and safety restraints, engineered interior surfaces and related components, advanced displays, thermal protection, lighting and control technology, military personnel parachutes and cargo delivery systems. Primary customers of this segment are airframe manufacturers and cabin system suppliers and subsystem suppliers, airlines, third party maintenance suppliers, military buying agencies and repair depots. Products are sold in the original equipment and aftermarket market channels. The Non-aviation segment includes operations that primarily develop, produce and market products for non-aviation markets. Major product offerings include seat belts and safety restraints for ground transportation applications, mechanical/electro-mechanical actuators and controls for space applications, hydraulic/electromechanical actuators and fuel valves for land based gas turbines, and refueling systems for heavy equipment used in mining, construction and other industries and turbine controls for the energy and oil and gas markets. Primary customers of this segment are off-road vehicle suppliers and subsystem suppliers, child restraint system suppliers, satellite and space system suppliers, manufacturers of heavy equipment used in mining, construction and other industries and turbine original equipment manufacturers, gas pipeline builders and electric utilities. The primary measurement used by management to review and assess the operating performance of each segment is EBITDA As Defined. The Company defines EBITDA As Defined as earnings before interest, taxes, depreciation and amortization plus certain non-operating items recorded as corporate expenses including refinancing costs, acquisition-related costs, transaction-related costs, foreign currency gains and losses, and non-cash compensation charges incurred in connection with the Company’s stock incentive plans. Acquisition-related costs represent accounting adjustments to inventory associated with acquisitions of businesses and product lines that were charged to cost of sales when the inventory was sold; costs incurred to integrate acquired businesses and product lines into the Company’s operations, facility relocation costs and other acquisition-related costs; transaction-related costs comprising deal fees; legal, financial and tax diligence expenses and valuation costs that are required to be expensed as incurred and other acquisition accounting adjustments. EBITDA As Defined is not a measurement of financial performance under GAAP. Although the Company uses EBITDA As Defined to assess the performance of its business and for various other purposes, the use of this non-GAAP financial measure as an analytical tool has limitations, and it should not be considered in isolation or as a substitute for analysis of the Company’s results of operations as reported in accordance with GAAP. The Company’s segments are reported on the same basis used internally for evaluating performance and for allocating resources. The accounting policies for each segment are the same as those described in the summary of significant accounting policies in the Company’s consolidated financial statements. Intersegment sales and transfers are recorded at values based on market prices, which creates intercompany profit on intersegment sales or transfers that is eliminated in consolidation. Intersegment sales were immaterial for the periods presented below. Certain corporate-level expenses are allocated to the operating segments. The Esterline businesses were acquired during the second quarter of fiscal 2019 and preliminarily assessed as a separate segment of the Company. During the third quarter of fiscal 2019, the Esterline businesses were integrated into TransDigm's existing Power & Control, Airframe and Non-aviation segments. The following table presents net sales by reportable segment (in thousands): Fiscal Years Ended September 30, 2019 2018 2017 Net sales to external customers Power & Control Commercial OEM $ 547,462 $ 498,654 $ 460,444 Commercial Aftermarket 710,099 665,663 606,389 Defense 1,164,545 974,818 860,411 Esterline (1) 313,468 — — Total Power & Control 2,735,574 2,139,135 1,927,244 Airframe Commercial OEM 597,765 508,671 497,612 Commercial Aftermarket 759,697 701,110 630,382 Defense 389,426 321,161 314,079 Esterline (1) 582,520 — — Total Airframe 2,329,408 1,530,942 1,442,073 Total Non-aviation 158,221 141,049 134,969 $ 5,223,203 $ 3,811,126 $ 3,504,286 (1) The sales market classifications associated with the acquired Esterline businesses are currently being assessed by TransDigm management to ensure the reported market classifications are in compliance with TransDigm policy and being computed consistently with that of the existing TransDigm legacy businesses. Therefore, the sales associated with the Esterline acquisition are excluded from the market classifications reported for the fiscal year ended September 30, 2019. The following table reconciles EBITDA As Defined by segment to consolidated income from continuing operations before income taxes (in thousands): Fiscal Years Ended September 30, 2019 2018 2017 EBITDA As Defined Power & Control $ 1,395,085 $ 1,114,464 $ 980,046 Airframe 1,062,679 759,253 726,630 Non-aviation 50,575 44,310 42,475 Total segment EBITDA As Defined 2,508,339 1,918,027 1,749,151 Unallocated corporate expenses 89,538 41,469 38,588 Total Company EBITDA As Defined 2,418,801 1,876,558 1,710,563 Depreciation and amortization 225,700 129,844 141,025 Interest expense - net 859,753 663,008 602,589 Acquisition-related costs 168,898 28,450 31,191 Stock compensation expense 93,362 58,481 45,524 Refinancing costs 3,013 6,396 39,807 Other, net 5,210 4,822 12,997 Income from continuing operations before income taxes $ 1,062,865 $ 985,557 $ 837,430 The following table presents capital expenditures and depreciation and amortization by segment (in thousands): Fiscal Years Ended September 30, 2019 2018 2017 Capital expenditures Power & Control $ 49,573 $ 38,762 $ 32,424 Airframe 48,027 32,028 34,526 Non-aviation 2,546 2,156 3,981 Corporate 1,445 395 82 $ 101,591 $ 73,341 $ 71,013 Depreciation and amortization Power & Control $ 98,366 $ 67,721 $ 85,681 Airframe 119,259 55,732 51,440 Non-aviation 6,280 5,276 2,745 Corporate 1,795 1,115 1,159 $ 225,700 $ 129,844 $ 141,025 The following table presents total assets by segment (in thousands): September 30, 2019 September 30, 2018 Total assets Power & Control $ 7,037,090 $ 5,698,524 Airframe 6,672,179 4,091,011 Non-aviation 261,841 234,770 Corporate 1,321,492 2,173,162 Assets of discontinued operations 962,129 — $ 16,254,731 $ 12,197,467

STOCK-BASED COMPENSATION

STOCK-BASED COMPENSATION	12 Months Ended
	Sep. 30, 2019
Share-based Payment Arrangement [Abstract]
STOCK-BASED COMPENSATION	STOCK-BASED COMPENSATION The Company’s stock compensation plans are designed to assist the Company in attracting, retaining, motivating and rewarding key employees, directors or consultants, and promoting the creation of long-term value for stockholders by closely aligning the interests of these individuals with those of the Company’s stockholders. The Company’s stock compensation plans provide for the granting of stock options and other stock-based incentives. Non-cash stock compensation expense recognized by the Company during the fiscal years ended September 30, 2019 , 2018 and 2017 was $93.4 million , $58.5 million and $45.5 million , respectively. The weighted-average grant date fair value of options granted during the fiscal years ended September 30, 2019 , 2018 and 2017 was $114.43 , $81.04 and $67.11 , respectively. Compensation expense is recognized based upon probability assessments of awards that are expected to vest in future periods. Such probability assessments are subject to revision and, therefore, unrecognized compensation expense is subject to future changes in estimate. As of September 30, 2019 , there was approximately $103.0 million of total unrecognized compensation expense related to non-vested awards expected to vest, which is expected to be recognized over a weighted-average period of 2.4 years . The fair value of the Company’s employee stock options was estimated at the date of grant using a Black-Scholes option-pricing model with the following weighted average assumptions for all options granted during the fiscal years ended: Fiscal Years Ended September 30, 2019 2018 2017 Risk-free interest rate 2.33% to 3.03% 2.01% to 2.84% 1.56% to 2.01% Expected life of options 5.5 years 5.2 years 5.0 years Expected dividend yield of stock — — — Expected volatility of stock 25% 25% 25% The risk-free interest rate is based upon the Treasury bond rates as of the grant date. The average expected life of stock-based awards is based on the Company’s actual historical exercise experience. Expected volatility of stock was calculated using a rate based upon the historical volatility of TransDigm’s common stock. Notwithstanding the special cash dividends declared and paid from time to time, the Company historically has not declared and paid regular cash dividends and does not anticipate declaring and paying regular cash dividends in future periods; thus, no dividend rate assumption is used. The total fair value of options vested during fiscal years ended September 30, 2019 , 2018 and 2017 was $37.7 million , $44.4 million and $42.9 million , respectively. 2019 Stock Option Plan In August 2019, the Board of Directors of TD Group adopted a new stock option plan, which was subsequently approved by stockholders on October 3, 2019. The 2019 stock option plan permits TD Group to award stock options to our key employees, directors or consultants. The total number shares of TD Group common stock reserved for issuance or delivery under the 2019 stock option plan is 4,000,000 , subject to adjustment in the event of any stock dividend or split, reorganization, recapitalization, merger, share exchange or any other similar corporate transaction or event. No shares have been issued from TD Group’s 2019 stock option plan. 2014 Stock Option Plan In July 2014, the Board of Directors of TD Group adopted the 2014 stock option plan, which was subsequently approved by stockholders on October 2, 2014. The 2014 stock option plan permits TD Group to award our key employees, directors or consultants stock options. The total number of shares of TD Group common stock reserved for issuance or delivery under the 2014 stock option plan is 5,000,000 , subject to adjustment in the event of any stock dividend or split, reorganization, recapitalization, merger, share exchange or any other similar corporate transaction or event. Performance Vested Stock Options —All of the options granted through September 30, 2019 under the 2014 stock option plan have been pursuant to an equity incentive program adopted by the Company in 2008. Under the 2008 equity incentive program, all of the options granted will vest based on the Company’s achievement of established operating performance goals. The following table summarizes the activity, pricing and other information for the Company’s performance vested stock-based award activity during the fiscal year ended September 30, 2019 : Number of Options Weighted-Average Exercise Price Per Option Weighted-Average Remaining Contractual Term Aggregate Intrinsic Value Outstanding at September 30, 2018 2,113,278 $ 283.84 Granted 1,184,680 393.32 Exercised (24,150 ) 251.22 Forfeited (105,350 ) 322.71 Expired (1,000 ) 303.90 Outstanding at September 30, 2019 3,167,458 $ 323.73 8.3 years $ 623,799,179 Expected to vest 1,820,010 $ 323.70 8.3 years $ 358,483,056 Exercisable at September 30, 2019 824,797 $ 315.16 8.2 years $ 169,504,031 At September 30, 2019 , there were 1,797,892 remaining shares available for award under TD Group’s 2014 stock option plan. 2006 Stock Incentive Plan In conjunction with the consummation of the Company’s initial public offering, a 2006 stock incentive plan was adopted by TD Group. In July 2008 and March 2011, the plan was amended to increase the number of shares available for issuance thereunder. TD Group reserved 8,119,668 shares of its common stock for issuance to key employees, directors or consultants under the plan. Awards under the plan were in the form of options, restricted stock or other stock-based awards. Options granted under the plan expire no later than the tenth anniversary of the applicable date of grant of the options, and have an exercise price of not less than the fair market value of our common stock on the date of grant. Restricted stock granted under the plan vested over three years . No restricted stock units remained outstanding as of September 30, 2018. Performance Vested Stock Options —All of the options granted under the 2006 stock incentive plan have been pursuant to an equity incentive program adopted by the Company in 2008. Under the 2008 equity incentive program, all of the options granted vest based on the Company’s achievement of established operating performance goals. The following table summarizes the activity, pricing and other information for the Company’s performance vested stock-based award activity during the fiscal year ended September 30, 2019 : Number of Options Weighted-Average Exercise Price Per Option Weighted-Average Remaining Contractual Term Aggregate Intrinsic Value Outstanding at September 30, 2018 3,878,127 $ 147.50 Granted — — Exercised (702,600 ) 107.90 Forfeited (41,505 ) 223.42 Expired — — Outstanding at September 30, 2019 3,134,022 $ 155.34 3.9 years $ 1,144,952,257 Expected to vest 141,080 $ 225.90 6.1 years $ 41,586,446 Exercisable at September 30, 2019 2,995,342 $ 152.08 3.8 years $ 1,104,053,108 The 2006 stock incentive plan expired on March 14, 2016 and no further shares were granted under the plan thereafter. 2003 Stock Option Plan Certain executives and key employees of the Company were granted stock options under TD Group’s 2003 stock option plan. Upon the closing of the acquisition of the Company by Warburg Pincus in 2003, certain employees rolled over certain then-existing options to purchase shares of common stock of TransDigm Holdings. These employees were granted rollover options to purchase an aggregate of 3,870,152 shares of common stock of TD Group (after giving effect to the 149.60 for 1.00 stock split effected on March 14, 2006) . All rollover options granted were fully vested on the date of grant. In addition to shares of common stock reserved for issuance upon the exercise of rollover options, an aggregate of 5,469,301 shares of TD Group’s common stock were reserved for issuance upon the exercise of new management options. In general, approximately 20% of all new management options vested based on employment service or a change in control. These time vested options had a graded vesting schedule of up to four years . There were no remaining time vested stock-based options outstanding as of September 30, 2016. Approximately 80% of all new management options vested (i) based upon the satisfaction of specified performance criteria, which is annual and cumulative EBITDA As Defined targets through 2008, or (ii) upon the occurrence of a change in control if the Investor Group (defined as Warburg Pincus and the other initial investors in TD Group) received a minimum specified rate of return. Unless terminated earlier, the options expire ten years from the date of grant. TD Group reserved a total of 9,339,453 shares of its common stock for issuance to the Company’s employees under the plan, which had all been issued as of September 30, 2013. Performance Vested Stock Options —The following table summarizes the activity, pricing and other information for the Company’s performance vested stock-based award activity during the fiscal year ended September 30, 2019 : Number of Options Weighted-Average Exercise Price Per Option Weighted-Average Remaining Contractual Term Aggregate Intrinsic Value Outstanding at September 30, 2018 77,829 $ 130.09 Granted — — Exercised — — Outstanding at September 30, 2019 77,829 $ 130.09 3.1 years $ 30,398,451 Exercisable at September 30, 2019 77,829 $ 130.09 3.1 years $ 30,398,451 The total intrinsic value of time, performance and rollover options exercised during the fiscal years ended September 30, 2019 , 2018 and 2017 was $240.2 million , $192.5 million and $61.1 million , respectively. In addition to shares issued pursuant to options exercised, during the fiscal year ended September 30, 2019 , 875 shares of common stock were issued with a weighted-average grant date fair value of $476.33 as payment to directors in lieu of cash. Dividend Equivalent Plans Pursuant to the Third Amended and Restated TransDigm Group Incorporated 2003 Stock Option Plan Dividend Equivalent Plan, the Second Amended and Restated TransDigm Group Incorporated 2006 Stock Incentive Plan Dividend Equivalent Plan, the 2014 Stock Option Plan Dividend Equivalent Plan and the 2019 Stock Option Plan Dividend Equivalent Plan, all of the options granted under the 2003 stock option plan, the 2006 stock incentive plan, the 2014 stock option plan and the 2019 stock option plan are entitled to certain dividend equivalent payments in the event of the declaration of a dividend by the Company. Dividend equivalent payments on vested options were $111.0 million , $56.1 million and $19.5 million during the fiscal years ended September 30, 2019 , 2018 and 2017 , respectively. At September 30, 2019 , there was $63.8 million recorded in accrued liabilities and $48.3 million accrued in other non-current liabilities on the consolidated balance sheets related to the future dividend equivalent payments.

LEASES

LEASES	12 Months Ended
	Sep. 30, 2019
Leases [Abstract]
LEASES	LEASES TransDigm leases certain manufacturing facilities, offices, equipment and vehicles. Such leases, some of which are noncancelable and, in many cases, include renewals, expire at various dates. Rental expense during the fiscal years ended September 30, 2019 , 2018 and 2017 was $25.5 million , $19.2 million and $19.0 million , respectively. Future minimum rental commitments at September 30, 2019 under operating leases having initial or remaining non-cancelable lease terms exceeding one year are $22.3 million in fiscal 2020 , $31.5 million in fiscal 2021 , $17.2 million in fiscal 2022 , $14.1 million in fiscal 2023 , $12.5 million in fiscal 2024 , and $27.8 million thereafter.

FAIR VALUE MEASUREMENTS

FAIR VALUE MEASUREMENTS	12 Months Ended
	Sep. 30, 2019
Fair Value Disclosures [Abstract]
FAIR VALUE MEASUREMENTS	FAIR VALUE MEASUREMENTS The following tables present our assets and liabilities that are measured at fair value on a recurring basis and are categorized using the fair value hierarchy. The fair value hierarchy has three levels based on the reliability of the inputs used to determine fair value. Level 1 inputs are quoted prices (unadjusted) in active markets for identical assets or liabilities. Level 2 inputs are quoted prices for similar assets and liabilities in active markets, quoted prices for identical or similar assets or liabilities in markets that are not active, and inputs (other than quoted prices) that are observable for the asset or liability, either directly or indirectly. Level 3 inputs are unobservable inputs for the asset or liability. A financial asset or liability’s classification within the hierarchy is determined based on the lowest level input that is significant to the fair value measurement. The following summarizes the carrying amounts and fair values of financial instruments (in thousands): September 30, 2019 September 30, 2018 Level Carrying Amount Fair Value Carrying Amount Fair Value Assets: Cash and cash equivalents 1 $ 1,467,486 $ 1,467,486 $ 2,073,017 $ 2,073,017 Interest rate cap agreements (1) 2 1,225 1,225 36,160 36,160 Interest rate swap agreements (2) 2 — — 11,634 11,634 Interest rate swap agreements (1) 2 — — 61,126 61,126 Foreign currency forward exchange contracts (2) 2 80 80 — — Foreign currency forward exchange contracts (1) 2 21 21 — — Liabilities: Interest rate swap agreements (3) 2 13,218 13,218 528 528 Interest rate swap agreements (4) 2 202,378 202,378 142 142 Foreign currency forward exchange contracts (3) 2 6,308 6,308 — — Foreign currency forward exchange contracts (4) 2 403 403 — — Short-term borrowings - trade receivable securitization facility (5) 1 349,519 349,519 299,519 299,519 Long-term debt, including current portion: Term loans (5) 2 7,448,549 7,477,552 7,509,205 7,607,323 5.50% 2020 Notes (5) 1 — — 547,813 548,625 6.00% 2022 Notes (5) 1 1,145,939 1,167,250 1,144,499 1,155,750 6.50% 2024 Notes (5) 1 1,194,310 1,239,000 1,193,134 1,215,000 6.50% 2025 Notes (5) 1 750,113 781,875 750,131 757,500 6.375% 2026 Notes (5) 1 943,210 998,688 942,202 942,875 6.875% 2026 Notes (5) 1 491,331 535,000 490,779 507,500 6.25% 2026 Notes (5) 1 3,942,182 4,290,000 — — 7.50% 2027 Notes (5) 1 544,700 595,375 — — Government refundable advances 2 39,195 39,195 — — Capital lease obligations 2 49,906 49,906 — — (1) Included in other non-current assets on the consolidated balance sheets. (2) Included in prepaid expenses and other on the consolidated balance sheets. (3) Included in accrued liabilities on the balance sheets. (4) Included in other non-current liabilities on the consolidated balance sheet. (5) The carrying amount of the debt instrument is presented net of the debt issuance costs, premium and discount. Refer to Note 12, “Debt,” for gross carrying amounts. The Company values its financial instruments using an industry standard market approach, in which prices and other relevant information are generated by market transactions involving identical or comparable assets or liabilities. No financial instruments were recognized using unobservable inputs. Interest rate swaps were measured at fair value using quoted market prices for the swap interest rate indexes over the term of the swap discounted to present value versus the fixed rate of the contract. The interest rate caps were measured at fair value using implied volatility rates of each individual caplet and the yield curve for the related periods. The Company’s derivative contracts consist of foreign currency exchange contracts and, from time to time, interest rate swap and cap agreements. These derivative contracts are over-the-counter, and their fair value is determined using modeling techniques that include market inputs such as interest rates, yield curves, and currency exchange rates. These contracts are categorized as Level 2 in the fair value hierarchy. The estimated fair value of the Company’s term loans was based on information provided by the agent under the Company’s senior secured credit facility. The estimated fair values of the Company’s notes were based upon quoted market prices. There has not been any impact to the fair value of derivative liabilities due to the Company's own credit risk. Similarly, there has not been any impact to the fair value of derivative assets based on the Company's evaluation of counterparties' credit risks. The fair value of cash and cash equivalents, trade accounts receivable-net and accounts payable approximated book value due to the short-term nature of these instruments at September 30, 2019 and 2018

DERIVATIVES AND HEDGING ACTIVIT

DERIVATIVES AND HEDGING ACTIVITIES	12 Months Ended
	Sep. 30, 2019
Derivative Instruments and Hedging Activities Disclosure [Abstract]
DERIVATIVES AND HEDGING ACTIVITIES	DERIVATIVES AND HEDGING ACTIVITIES The Company is exposed to, among other things, the impact of changes in foreign currency exchange rates and interest rates in the normal course of business. The Company’s risk management program is designed to manage the exposure and volatility arising from these risks, and utilizes derivative financial instruments to offset a portion of these risks. The Company uses derivative financial instruments only to the extent necessary to hedge identified business risks and does not enter into such transactions for trading purposes. The Company generally does not require collateral or other security with counterparties to these financial instruments and is therefore subject to credit risk in the event of nonperformance; however, the Company monitors credit risk and currently does not anticipate nonperformance by other parties. These derivative financial instruments do not subject the Company to undue risk, as gains and losses on these instruments generally offset gains and losses on the underlying assets, liabilities, or anticipated transactions that are being hedged. The Company has agreements with each of its swap and cap counterparties that contain a provision whereby if the Company defaults on the credit facility the Company could also be declared in default on its swaps and caps, resulting in an acceleration of payment under the swaps and caps. All derivative financial instruments are recorded at fair value in the consolidated balance sheets. For a derivative that has not been designated as an accounting hedge, the change in the fair value is recognized immediately through earnings. For a derivative that has been designated as an accounting hedge of an existing asset or liability (a fair value hedge), the change in the fair value of both the derivative and underlying asset or liability is recognized immediately through earnings. For a derivative designated as an accounting hedge of an anticipated transaction (a cash flow hedge), the change in the fair value is recorded on the consolidated balance sheet in accumulated other comprehensive income to the extent the derivative is effective in mitigating the exposure related to the anticipated transaction. The change in the fair value related to the ineffective portion of the hedge, if any, is immediately recognized in earnings. The amount recorded within accumulated other comprehensive income is reclassified into earnings in the same period during which the underlying hedged transaction affects earnings. Interest Rate Swap and Cap Agreements – Interest rate swap and cap agreements are used to manage interest rate risk associated with floating-rate borrowings under our credit facility. The interest rate swap and cap agreements utilized by the Company effectively modify the Company’s exposure to interest rate risk by converting a portion of the Company’s floating-rate debt to a fixed rate basis through the expiration date of the interest rate swap and cap agreements, thereby reducing the impact of interest rate changes on future interest expense. These agreements involve the receipt of floating rate amounts in exchange for fixed rate interest payments over the term of the agreements without an exchange of the underlying principal amount. These derivative instruments qualify as effective cash flow hedges under GAAP. For these cash flow hedges, the effective portion of the gain or loss from the financial instruments was initially reported as a component of accumulated other comprehensive (loss) income in stockholders’ deficit and subsequently reclassified into earnings in the same line as the hedged item in the same period or periods during which the hedged item affected earnings. As the interest rate swap and cap agreements are used to manage interest rate risk, any gains or losses from the derivative instruments that are reclassified into earnings are recognized in interest expense - net in the consolidated statements of income. The following table summarizes the Company’s interest rate swap agreements: Aggregate Notional Amount (in millions) Start Date End Date Related Term Loans Conversion of Related Variable Rate Debt to Fixed Rate of: $750 3/31/2016 6/30/2020 Tranche E 5.3% (2.8% plus the 2.5% margin percentage) $500 6/29/2018 3/31/2025 Tranche E 5.5% (3.0% plus the 2.5% margin percentage) $750 6/30/2020 6/30/2022 Tranche E 5.0% (2.5% plus the 2.5% margin percentage) $1,500 6/30/2022 3/31/2025 Tranche E 5.6% (3.1% plus the 2.5% margin percentage) $1,000 6/28/2019 6/30/2021 Tranche F 4.3% (1.8% plus the 2.5% margin percentage) $1,400 6/30/2021 3/31/2023 Tranche F 5.5% (3.0% plus the 2.5% margin percentage) $500 12/30/2016 12/31/2021 Tranche G 4.4% (1.9% plus the 2.5% margin percentage) $400 9/30/2017 9/30/2022 Tranche G 4.4% (1.9% plus the 2.5% margin percentage) $900 12/31/2021 6/28/2024 Tranche G 5.6% (3.1% plus the 2.5% margin percentage) $400 9/30/2022 6/28/2024 Tranche G 5.5% (3.0% plus the 2.5% margin percentage) The following table summarizes the Company’s interest rate cap agreements: Aggregate Notional Amount Start Date End Date Related Debt Offsets Variable Rate Debt Attributable to Fluctuations Above: $750 9/30/2015 6/30/2020 Tranche E Three month LIBO rate of 2.5% $750 6/30/2020 6/30/2022 Tranche E Three month LIBO rate of 2.5% $400 6/30/2016 6/30/2021 Tranche F Three month LIBO rate of 2.0% $400 12/30/2016 12/30/2021 Tranche G Three month LIBO rate of 2.5% Certain derivative asset and liability balances are offset where master netting agreements provide for the legal right of setoff. For classification purposes, we record the net fair value of each type of derivative position that is expected to settle in less than one year with each counterparty as a net current asset or liability and each type of long-term position as a net non-current asset or liability. The amounts shown in the table below represent the gross amounts of recognized assets and liabilities, the amounts offset in the consolidated balance sheet and the net amounts of assets and liabilities presented therein. September 30, 2019 September 30, 2018 Asset Liability Asset Liability Interest rate cap agreements $ 1,225 $ — $ 36,160 $ — Interest rate swap agreements (1) — (215,596 ) 72,090 — Total 1,225 (215,596 ) 108,250 — Effect of counterparty netting — — 670 (670 ) Net derivatives as classified in the balance sheet (2) $ 1,225 $ (215,596 ) $ 108,920 $ (670 ) (1) The increase in the interest rate swap liability is primarily attributable to a downward trend in the LIBO rate during fiscal 2019. (2) Refer to Note 20, "Fair Value Measurements," for the consolidated balance sheet classification of our interest rate swap and cap agreements. Based on the fair value amounts of the interest rate swap and cap agreements determined as of September 30, 2019 , the estimated net amount of existing gains and losses and caplet amortization expected to be reclassified into interest expense within the next twelve months is approximately $17.2 million . Effective September 30, 2016, the Company redesignated the interest rate cap agreements related to the $400 million and the $750 million aggregate notional amount with cap rates of 2.0% and 2.5% , respectively, based on the expected probable cash flows associated with the 2016 term loans and 2015 term loans in consideration of the Company’s ability to select one-month, two-month, three-month, or six-month LIBO rate set forth in the Second Amended and Restated Credit Agreement. Accordingly, amounts previously recorded as a component of accumulated other comprehensive income (loss) in stockholder’s deficit amortized into interest expense was $4.8 million and $4.0 million for the fiscal years ended September 30, 2019 and 2018, respectively. The accumulated other comprehensive income to be reclassified into interest expense over the remaining term of the cap agreements is $6.2 million with a related tax benefit of $1.5 million as of September 30, 2019 . Effective December 30, 2017, the Company redesignated the existing interest rate swap agreements related to the $750 million , $500 million , $1,000 million and $750 million aggregate notional amounts with swap rates of 5.0% , 4.4% , 4.3% and 5.3% , respectively, based on the expected probable cash flows associated with certain term loans in consideration of the Company’s removal of the LIBO rate floor on the certain term loans as set forth in Amendment No. 4 to the Second Amended and Restated Credit Agreement. Accordingly, the amount recorded as a component of accumulated other comprehensive income in stockholders’ deficit related to these redesignated interest rate swap hedges will be amortized into earnings based on the original maturity date of the related interest rate swap agreements. Amounts previously recorded as a component of accumulated other comprehensive income in stockholder’s deficit amortized into interest expense was $1.1 million and $0.8 million for the fiscal years ended September 30, 2019 and 2018, respectively. The accumulated other comprehensive income to be reclassified into interest income over the remaining term of the swap agreements is $1.7 million with a related tax expense of $0.4 million as of September 30, 2019. Effective March 31, 2018, the Company redesignated the existing interest rate swap agreements related to the $1,000 million aggregate notional amount with a swap rate of 4.9% , which expired in June 2019, and the $400 million aggregate notional amount with swap rate of 4.4% based on the expected probable cash flows associated with certain term loans in consideration of the Company’s removal of the LIBO rate floor on the certain term loans as set forth in the refinancing facility agreement dated February 22, 2018 related to the Second Amended and Restated Credit Agreement. Accordingly, the amount recorded as a component of accumulated other comprehensive income in stockholders’ deficit related to these redesignated interest rate swap hedges will be amortized into earnings based on the original maturity date of the related interest rate swap agreements. Amounts previously recorded as a component of accumulated other comprehensive income in stockholder’s deficit amortized into interest income was $2.8 million and $1.4 million for the fiscal years ended September 30, 2019 and 2018. The accumulated other comprehensive income to be reclassified into interest income over the remaining term of the swaps agreements is $8.6 million with a related tax expense of $2.0 million as of September 30, 2019 . Foreign Currency Forward Exchange Contracts – The Company transacts business in various foreign currencies, which subjects the Company’s cash flows and earnings to exposure related to changes in foreign currency exchange rates. These exposures arise primarily from purchases or sales of products and services from third parties. Foreign currency forward exchange contracts provide for the purchase or sale of foreign currencies at specified future dates at specified exchange rates, and are used to offset changes in the fair value of certain assets or liabilities or forecasted cash flows resulting from transactions denominated in foreign currencies. At September 30, 2019 , the Company had outstanding foreign currency forward exchange contracts principally to sell U.S. dollars with notional amounts of $217.2 million . These notional values consist primarily of contracts for the British pound sterling, Canadian dollar, and European euro and are stated in U.S. dollar equivalents at spot exchange rates at the respective dates. During the fiscal year ended September 30, 2019 , the the Company recognized gains on foreign currency forward exchange contracts designated as fair value hedges of $0.4 million in cost of sales in the consolidated statement of income. During the fiscal year ended September 30, 2019 , the gains the Company reclassified on foreign currency forward exchange contracts designated as cash flow hedges in the consolidated income statement are immaterial. The losses were previously recorded as a component of accumulated other comprehensive (loss) income in stockholders' deficit. During the fiscal year ended September 30, 2019 , the Company recorded a gain of $0.1 million on foreign currency forward exchange contracts that have not been designated as accounting hedges. These foreign currency exchange gains are included in selling and administrative expenses. There was an immaterial impact to the Company’s earnings related to the ineffective portion of any hedging instruments during the fiscal year ended September 30, 2019 . In addition, there was an immaterial impact to the Company’s earnings when a hedged firm commitment no longer qualified as a fair value hedge or when a hedged forecasted transaction no longer qualified as a cash flow hedge during the fiscal year ended September 30, 2019 . Amounts related to foreign currency forward exchange contracts included in accumulated other comprehensive (loss) income in stockholders' deficit are reclassified into earnings when the hedged transaction settles. The Company expects to reclassify approximately $5.3 million of net losses into earnings over the next 12 months. The maximum duration of the Company’s foreign currency cash flow hedge contracts at September 30, 2019 was 18 months.

ACCUMULATED OTHER COMPREHENSIVE

ACCUMULATED OTHER COMPREHENSIVE LOSS	12 Months Ended
	Sep. 30, 2019
Equity [Abstract]
ACCUMULATED OTHER COMPREHENSIVE INCOME (LOSS)	ACCUMULATED OTHER COMPREHENSIVE (LOSS) INCOME The following table presents the components of accumulated other comprehensive (loss) income, net of taxes, for the fiscal years ended September 30, 2019 , 2018 and 2017 (in thousands): Unrealized (loss) gain on derivatives designated and qualifying as cash flow hedges (1) Defined benefit pension plan activity (2) Currency translation adjustment Total Balance at September 30, 2017 $ (26,669 ) $ (16,365 ) $ (42,109 ) $ (85,143 ) Current-period other comprehensive gain (loss) 91,226 5,636 (10,253 ) 86,609 Amounts reclassified from AOCI related to derivative instruments 2,634 — — 2,634 Net current-period other comprehensive gain (loss) 93,860 5,636 (10,253 ) 89,243 Balance at September 30, 2018 67,191 (10,729 ) (52,362 ) 4,100 Cumulative effect of ASU 2018-02, adopted October 1, 2018 (2,199 ) — — (2,199 ) Current-period other comprehensive (loss) gain (240,776 ) (29,004 ) (114,856 ) (384,636 ) Amounts reclassified from AOCI related to derivative instruments 3,754 — — 3,754 Net current-period other comprehensive (loss) gain (239,221 ) (29,004 ) (114,856 ) (383,081 ) Balance at September 30, 2019 $ (172,030 ) $ (39,733 ) $ (167,218 ) $ (378,981 ) (1) Unrealized gain (loss) represents derivative instruments, net of taxes of $69,660 , $(33,923) and $(20,663) for the fiscal years ended September 30, 2019 , 2018 and 2017 , respectively. (2) Defined benefit pension plan and other post-retirement plan activity represents pension liability adjustments, net of taxes of $8,513 , $(1,487) and $(4,130) for the fiscal years ended September 30, 2019 , 2018 and 2017 , respectively. A summary of reclassifications out of accumulated other comprehensive (loss) income for the fiscal years ended September 30, 2019 and 2018 is provided below (in thousands): Amount Reclassified Fiscal Years Ended September 30, Description of reclassifications out of accumulated other comprehensive (loss) income 2019 2018 Amortization from redesignated interest rate swap and cap agreements (1) $ 3,060 $ 3,443 Losses from settlement of foreign currency forward exchange contracts (2) (20 ) — Deferred tax expense (benefit) on reclassifications out of accumulated other comprehensive (loss) income 714 (809 ) Losses reclassified into earnings, net of tax $ 3,754 $ 2,634 (1) This component of accumulated other comprehensive (loss) income is included in interest expense (see Note 21, “Derivatives and Hedging Activities,” for additional information). (2) This component of accumulated other comprehensive (loss) income is included in net sales (see Note 21, “Derivatives and Hedging Activities,” for additional information).

DISCONTINUED OPERATIONS

DISCONTINUED OPERATIONS	12 Months Ended
	Sep. 30, 2019
DISCONTINUED OPERATIONS [Abstract]
Disposal Groups, Including Discontinued Operations, Disclosure [Text Block]	DISCONTINUED OPERATIONS Current Year Divestitures On July 21, 2019, TransDigm entered into a binding offer (the “Put Agreement”) with Eaton Corporation plc (“Eaton”) for the acquisition by Eaton of the shares of Souriau SAS, Souriau USA Inc. and Sunbank Family of Companies LLC which comprise the Souriau-Sunbank Connection Technologies business (“Souriau-Sunbank”). Pursuant to the terms of the Put Agreement, after completion of the consultation process with the French works council, TransDigm has the right to require Eaton to enter into a securities purchase agreement (the “Purchase Agreement”) providing for the purchase by Eaton from TransDigm of the shares of Souriau-Sunbank. The Purchase Agreement was entered into by the parties on October 28, 2019. Pursuant to the terms of the Purchase Agreement, Eaton will purchase the shares of the Souriau-Sunbank for a cash purchase price of approximately $920 million . The transaction is subject to execution and delivery of the Purchase Agreement and other definitive agreements, the satisfaction or waiver of customary closing conditions and receipt of required regulatory approvals, all of which have been received other than the French foreign investment approval. The parties expect to complete the transaction during the first quarter of fiscal 2020. Souriau-Sunbank, which is a reporting unit within TransDigm’s Non-aviation segment, is classified as held-for-sale as of September 30, 2019. The divestiture represents a strategic shift in TransDigm’s business and, in accordance with US GAAP, qualify as discontinued operations. Therefore, the results of operations of Souriau-Sunbank are presented in discontinued operations in the accompanying consolidated financial statements for all periods presented since the date acquired. On September 20, 2019, TransDigm completed the divestiture of its Esterline Interface Technology (“EIT”) group of businesses to an affiliate of KPS Capital Partners, LP for approximately $190 million . EIT was acquired by TransDigm as part of its acquisition of Esterline Technologies Corporation in March 2019 and was included in TransDigm’s Non-aviation segment. The divestiture represents a strategic shift in TransDigm’s business and, in accordance with US GAAP, qualify as discontinued operations. Therefore, the results of operations of EIT are presented in discontinued operations in the accompanying consolidated financial statements for all periods presented since the date acquired. The income from discontinued operations was $50.4 million in the consolidated statements of income for the fiscal year ended September 30, 2019. Cash related to discontinued operations, which has been excluded from the consolidated statement of cash flows, includes net cash provided by operating activities of $35.3 million and net cash used in investing activities of $10.6 million . The following is the summarized operating results for Souriau-Sunbank and EIT for the fiscal year ended September 30, 2019 (in thousands): Fiscal Year Ended September 30, 2019 Souriau-Sunbank EIT Total Net sales $ 199,356 $ 94,619 $ 293,975 (Loss) income from discontinued operations before income taxes (17,176 ) 17,112 (64 ) Income tax benefit (expense) 14,254 (1,131 ) 13,123 (Loss) income from discontinued operations, net of tax, including noncontrolling interests (2,922 ) 15,981 13,059 Gain from sale of discontinued operations, net of tax — 37,619 37,619 Less: Income attributable to noncontrolling interests (98 ) (148 ) (246 ) (Loss) income from discontinued operations, net of tax $ (3,020 ) $ 53,452 $ 50,432 At September 30, 2019 , Souriau-Sunbank’s assets held-for-sale and liabilities held-for-sale are $962.1 million and $156.7 million, respectively. Under US GAAP, assets held for sale are to be reported at lower of its carrying amount or fair value less cost to sell. The following is the summarized balance sheet of Souriau-Sunbank’s assets held-for-sale and liabilities held-for-sale as of September 30, 2019 (in thousands): Assets and Liabilities of Discontinued Operations Held-for-Sale Fiscal Year Ended September 30, 2019 Cash and cash equivalents $ 28,545 Trade accounts receivable—Net 66,619 Inventories—Net 87,919 Prepaid expenses and other 1,740 Property, plant and equipment—Net 100,759 Goodwill 480,310 Other intangibles—Net 194,483 Other 1,754 Total assets of discontinued operations $ 962,129 Accounts payable $ 33,338 Accrued liabilities 55,031 Long-term debt 5,793 Deferred income taxes 41,769 Other 20,808 Total liabilities of discontinued operations $ 156,739 Prior Year Divestitures In connection with the settlement of a Department of Justice investigation into the competitive effects of the acquisition, during the fourth quarter of 2017, the Company committed to dispose of the Schroth business. Therefore, Schroth was classified as held-for-sale as of September 30, 2017. The results of operations of Schroth are presented in discontinued operations in the accompanying consolidated financial statements for all periods presented. On January 26, 2018, the Company completed the sale of Schroth in a management buyout to a private equity fund and certain members of Schroth management for approximately $61.4 million , which includes a working capital adjustment of $0.3 million that was paid on July 6, 2018. The Company previously acquired Schroth in February 2017. The loss from discontinued operations was $4.5 million and $31.7 million in the consolidated statements of income for the fiscal years ended September 30, 2018 and 2017, respectively. Previously, in the fourth quarter of fiscal 2017, the Company recorded a $32.0 million impairment charge to write down the Schroth assets to fair value. The impairment charge was based on an internal assessment of the recovery of Schroth’s assets. The following is the summarized operating results for Schroth for the years ended September 30, 2018 and 2017 (in thousands): Fiscal Years Ended September 30, 2018 2017 Net sales $ 11,808 $ 24,590 Income (loss) from discontinued operations before income taxes 354 (5,709 ) Loss on classification as held-for-sale before income taxes — (32,000 ) Income tax benefit 2,016 6,055 Income (loss) from discontinued operations, net of tax 2,370 (31,654 ) Loss on sale of discontinued operations, net of tax (6,844 ) — Loss from discontinued operations, net of tax $ (4,474 ) $ (31,654 )

COMMITMENTS AND CONTINGENCIES (

COMMITMENTS AND CONTINGENCIES (Notes)	12 Months Ended
	Sep. 30, 2019
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies Disclosure [Text Block]	COMMITMENTS AND CONTINGENCIES On August 8, 2019, a fire caused significant damage to the Niort, France operating facility of Leach International Europe, which is a subsidiary of TransDigm acquired via the Esterline acquisition. Leach International Europe’s results are reported within the Company’s Power & Control segment. The facility as well as certain machinery, equipment and inventory sustained damage. The Company suspended operations at the Niort facility as a result of the fire; however, it is in the process of transferring certain operations to temporary facilities while the facility is rebuilt, which is the rebuilding of the facility is expected to take up to 18 months. The Company’s insurance covers damage to the facility, equipment, inventory, and other assets, at replacement cost, as well as business interruption, and recovery-related expenses caused by the fire, subject to a $1 million deductible and certain sub-limits based on the nature of the covered item. Anticipated insurance recoveries related to losses and incremental costs incurred are recognized when receipt is probable. Anticipated insurance recoveries in excess of net book value of the damaged property and inventory will not be recorded until all contingencies relating to the claim have been resolved. The timing of and amounts of ultimate insurance recoveries is not known at this time. For the fiscal year ended September 30, 2019, the Company recorded fire-related expense of $2.4 million , net of insurance recovery receivable, and is recorded within other expense in the consolidated statement of income.

QUARTERLY FINANCIAL DATA (UNAUD

QUARTERLY FINANCIAL DATA (UNAUDTIED)	12 Months Ended
	Sep. 30, 2019
Quarterly Financial Information Disclosure [Abstract]
QUARTERLY FINANCIAL DATA (UNAUDITED)	QUARTERLY FINANCIAL DATA (UNAUDITED) First Quarter Second Quarter Third Quarter Fourth Quarter (in thousands, except per share amounts) Fiscal Year Ended September 30, 2019 (1) Net sales (2) $ 993,302 $ 1,167,520 $ 1,521,061 $ 1,541,320 Gross profit (2) 564,116 649,964 713,109 882,082 Income from continuing operations, net of tax (2) 196,042 200,021 127,659 317,157 Income from discontinued operations, net of tax (2) — 2,611 16,951 30,870 Net income attributable to noncontrolling interests (2) — (224 ) (160 ) (1,157 ) Net income attributable to TD Group (2) $ 196,042 $ 202,408 $ 144,450 $ 346,870 Net earnings per share from continuing operations—basic and diluted (3) $ 3.05 $ 3.55 $ 2.27 $ 4.08 Net earnings per share from discontinued operations—basic and diluted (3) — 0.05 0.30 0.55 Net earnings per share (3) $ 3.05 $ 3.60 $ 2.57 $ 4.63 First Quarter Second Quarter Third Quarter Fourth Quarter (in thousands, except per share amounts) Fiscal Year Ended September 30, 2018 (1) Net sales (2) $ 847,960 $ 933,070 $ 980,662 $ 1,049,434 Gross profit (2) 476,650 534,074 569,520 597,266 Income from continuing operations, net of tax (2) 312,011 201,840 217,391 230,294 Income (loss) from discontinued operations, net of tax (2) 2,764 (5,562 ) (145 ) (1,531 ) Net income attributable to TD Group (2) $ 314,775 $ 196,278 $ 217,246 $ 228,763 Net earnings per share from continuing operations—basic and diluted (3) $ 4.60 $ 3.63 $ 3.91 $ 4.14 Net earnings (loss) per share from discontinued operations—basic and diluted (3) 0.05 (0.10 ) — (0.03 ) Net earnings per share (3) $ 4.65 $ 3.53 $ 3.91 $ 4.11 (1) Results adjusted to reflect amounts reclassified to discontinued operations due to the Company’s classification of Souriau-Sunbank and EIT at September 30, 2019, and Schroth at September 30, 2017, as discontinued operations. See Note 23, “Discontinued Operations,” for additional information. (2) The Company’s operating results include the results of operations of acquisitions from the effective date of each acquisition. See Note 2 “Acquisitions and Divestitures,” for additional details. (3) The sum of the earnings per share for the four quarters in a year does not necessarily equal the total year earnings per share due to the weighted average number of shares outstanding in each quarter.

SUBSEQUENT EVENTS

SUBSEQUENT EVENTS	12 Months Ended
	Sep. 30, 2019
Subsequent Event [Line Items]
Subsequent Events [Text Block]	SUBSEQUENT EVENTS On October 29, 2019, the Company entered into a purchase agreement in connection with a private offering of $2.65 billion aggregate principal amount in 5.50% senior subordinated notes due November 15, 2027. The settlement of the debt financing transaction occurred on November 13, 2019. The notes were issued at a price of 100% of their principal amount. The Company will use a portion of the net proceeds from the offering of the notes to redeem all of its outstanding (aggregate principal amount of $1.15 billion ) 2022 Notes. The remaining net proceeds will be used for general corporate purposes, which may include potential future acquisitions, dividends or repurchases under its stock repurchase program.

SUPPLEMENTAL GUARANTOR INFORMAT

SUPPLEMENTAL GUARANTOR INFORMATION	12 Months Ended
	Sep. 30, 2019
Organization, Consolidation and Presentation of Financial Statements [Abstract]
SUPPLEMENTAL GUARANTOR INFORMATION	SUPPLEMENTAL GUARANTOR INFORMATION TransDigm Inc.’s 2022 Notes, 2024 Notes, 2025 Notes, 6.375% 2026 Notes, 2026 Secured Notes and 2027 Notes are jointly and severally guaranteed, on a senior subordinated basis, by TD Group, TransDigm UK Holdings plc ("TransDigm UK") and TransDigm Inc.’s Domestic Restricted Subsidiaries, as defined in the applicable Indentures. TransDigm UK's 6.875% 2026 Notes are jointly and severally guaranteed, on a senior subordinated basis, by TD Group, TransDigm Inc. and TransDigm Inc.'s Domestic Restricted Subsidiaries as defined in the applicable indenture. The following supplemental consolidating financial information presents, in separate columns, the balance sheets of the Company as of September 30, 2019 and September 30, 2018 and its statements of income and comprehensive income and cash flows for the fiscal years ended September 30, 2019 , 2018 and 2017 for (i) TransDigm Group on a parent only basis with its investment in subsidiaries recorded under the equity method, (ii) TransDigm Inc. including its directly owned operations and non-operating entities, excluding TransDigm UK, (iii) TransDigm UK (iv) the Subsidiary Guarantors (other than TransDigm UK) on a combined basis, (v) Non-Guarantor Subsidiaries and (vi) the Company on a consolidated basis. Separate financial statements of TransDigm Inc. are not presented because TransDigm Inc.’s 2022 Notes, 2024 Notes, 2025 Notes, 6.375% 2026 Notes, 2026 Secured Notes and 2027 Notes are fully and unconditionally guaranteed on a senior subordinated basis by TD Group, TransDigm UK and all of TransDigm Inc's Domestic Restricted Subsidiaries and because TD Group has no significant operations or assets separate from its investment in TransDigm Inc. Separate financial statements of TransDigm UK are not presented because TransDigm UK's 6.875% 2026 Notes, issued in May 2018, are fully and unconditionally guaranteed on a senior subordinated basis by TD Group, TransDigm Inc. and all of TransDigm Inc.'s Domestic Restricted Subsidiaries. TRANSDIGM GROUP INCORPORATED CONSOLIDATING BALANCE SHEET AS OF SEPTEMBER 30, 2019 (Amounts in thousands) TransDigm Group TransDigm Inc. Transdigm UK Subsidiary Guarantors Non-Guarantor Subsidiaries Eliminations Total Consolidated ASSETS CURRENT ASSETS: Cash and cash equivalents $ 29 $ 1,092,209 $ 280 $ (12,263 ) $ 387,231 $ — $ 1,467,486 Trade accounts receivable—Net — — — 172,099 895,504 — 1,067,603 Inventories—Net — 52,291 — 879,681 315,966 (15,289 ) 1,232,649 Assets held-for-sale — — — 206,419 755,710 — 962,129 Prepaid expenses and other — 27,175 — 45,220 62,985 — 135,380 Total current assets 29 1,171,675 280 1,291,156 2,417,396 (15,289 ) 4,865,247 INVESTMENT IN SUBSIDIARIES AND INTERCOMPANY BALANCES (2,894,934 ) 14,729,513 974,663 16,373,195 6,898,707 (36,081,144 ) — PROPERTY, PLANT AND EQUIPMENT—NET — 16,971 — 513,337 226,449 — 756,757 GOODWILL — 82,924 — 5,544,529 2,192,650 — 7,820,103 OTHER INTANGIBLE ASSETS—NET — 25,444 — 2,063,944 654,432 — 2,743,820 OTHER — 5,364 — 33,931 29,509 — 68,804 TOTAL ASSETS $ (2,894,905 ) $ 16,031,891 $ 974,943 $ 25,820,092 $ 12,419,143 $ (36,096,433 ) $ 16,254,731 LIABILITIES AND STOCKHOLDERS’ EQUITY (DEFICIT) CURRENT LIABILITIES: Current portion of long-term debt $ — $ 75,688 $ — $ 1,020 $ 3,505 $ — $ 80,213 Short-term borrowings—trade receivable securitization facility — — — — 349,519 — 349,519 Accounts payable — 16,517 — 160,793 99,280 — 276,590 Accrued liabilities — 215,562 12,892 237,026 210,215 — 675,695 Liabilities held-for-sale — — — 22,306 134,433 — 156,739 Total current liabilities — 307,767 12,892 421,145 796,952 — 1,538,756 LONG-TERM DEBT — 15,893,314 491,331 49,240 35,336 — 16,469,221 DEFERRED INCOME TAXES — — — 346,456 94,361 — 440,817 OTHER NON-CURRENT LIABILITIES — 315,262 — 232,520 143,238 — 691,020 Total liabilities — 16,516,343 504,223 1,049,361 1,069,887 — 19,139,814 TD GROUP STOCKHOLDERS’ (DEFICIT) EQUITY (2,894,905 ) (484,452 ) 470,720 24,770,731 11,339,434 (36,096,433 ) (2,894,905 ) NONCONTROLLING INTEREST — — — — 9,822 — 9,822 TOTAL LIABILITIES AND STOCKHOLDERS’ (DEFICIT) EQUITY $ (2,894,905 ) $ 16,031,891 $ 974,943 $ 25,820,092 $ 12,419,143 $ (36,096,433 ) $ 16,254,731 TRANSDIGM GROUP INCORPORATED CONSOLIDATING BALANCE SHEET AS OF SEPTEMBER 30, 2018 (Amounts in thousands) TransDigm Group TransDigm Inc. TransDigm UK Subsidiary Guarantors Non-Guarantor Subsidiaries Eliminations Total Consolidated ASSETS CURRENT ASSETS: Cash and cash equivalents $ 389 $ 1,821,437 $ 125 $ (1,763 ) $ 252,829 $ — $ 2,073,017 Trade accounts receivable—Net — — — 40,916 663,394 — 704,310 Inventories—Net — 45,262 — 648,574 115,913 (4,457 ) 805,292 Prepaid expenses and other — 16,231 — 47,020 11,417 — 74,668 Total current assets 389 1,882,930 125 734,747 1,043,553 (4,457 ) 3,657,287 INVESTMENT IN SUBSIDIARIES AND INTERCOMPANY BALANCES (1,808,860 ) 10,459,497 1,099,886 8,928,726 2,160,236 (20,839,485 ) — PROPERTY, PLANT AND EQUIPMENT—NET — 15,562 — 319,567 53,204 — 388,333 GOODWILL — 97,002 — 5,466,148 660,140 — 6,223,290 OTHER INTANGIBLE ASSETS—NET — 31,362 — 1,514,983 242,059 — 1,788,404 OTHER — 104,633 — 29,805 5,715 — 140,153 TOTAL ASSETS $ (1,808,471 ) $ 12,590,986 $ 1,100,011 $ 16,993,976 $ 4,164,907 $ (20,843,942 ) $ 12,197,467 LIABILITIES AND STOCKHOLDERS’ EQUITY (DEFICIT) CURRENT LIABILITIES: Current portion of long-term debt $ — $ 75,817 $ — $ — $ — $ — $ 75,817 Short-term borrowings—trade receivable securitization facility — — — — 299,519 — 299,519 Accounts payable — 18,470 — 115,735 39,398 — 173,603 Accrued liabilities — 118,600 13,274 162,618 56,951 — 351,443 Total current liabilities — 212,887 13,274 278,353 395,868 — 900,382 LONG-TERM DEBT — 12,011,166 490,780 — — — 12,501,946 DEFERRED INCOME TAXES — 345,357 — (2,329 ) 56,468 — 399,496 OTHER NON-CURRENT LIABILITIES — 77,573 — 104,829 21,712 — 204,114 Total liabilities — 12,646,983 504,054 380,853 474,048 — 14,005,938 TD GROUP STOCKHOLDERS’ (DEFICIT) EQUITY (1,808,471 ) (55,997 ) 595,957 16,613,123 3,690,859 (20,843,942 ) (1,808,471 ) NONCONTROLLING INTEREST — — — — — — — TOTAL LIABILITIES AND STOCKHOLDERS’ (DEFICIT) EQUITY $ (1,808,471 ) $ 12,590,986 $ 1,100,011 $ 16,993,976 $ 4,164,907 $ (20,843,942 ) $ 12,197,467 TRANSDIGM GROUP INCORPORATED CONSOLIDATING STATEMENT OF INCOME AND COMPREHENSIVE INCOME FOR THE YEAR ENDED SEPTEMBER 30, 2019 (Amounts in thousands) TransDigm Group TransDigm Inc. TransDigm UK Subsidiary Guarantors Non-Guarantor Subsidiaries Eliminations Total Consolidated NET SALES $ — $ 186,360 $ — $ 4,103,848 $ 1,105,379 $ (172,384 ) $ 5,223,203 COST OF SALES — 109,414 — 1,771,217 705,685 (172,384 ) 2,413,932 GROSS PROFIT — 76,946 — 2,332,631 399,694 — 2,809,271 SELLING AND ADMINISTRATIVE EXPENSES — 258,465 14 348,928 140,366 — 747,773 AMORTIZATION OF INTANGIBLE ASSETS — 925 — 98,868 35,159 — 134,952 (LOSS) INCOME FROM OPERATIONS — (182,444 ) (14 ) 1,884,835 224,169 — 1,926,546 INTEREST EXPENSE (INCOME)—NET — 855,325 35,420 (11,638 ) (19,354 ) — 859,753 REFINANCING COSTS — 2,745 268 — — — 3,013 OTHER (INCOME) EXPENSE — (71,003 ) 89,539 (590,135 ) 572,514 — 915 EQUITY IN INCOME OF SUBSIDIARIES (889,770 ) (1,866,584 ) — — — 2,756,354 — INCOME (LOSS) FROM CONTINUING OPERATIONS BEFORE INCOME TAXES 889,770 897,073 (125,241 ) 2,486,608 (328,991 ) (2,756,354 ) 1,062,865 INCOME TAX PROVISION — — — 187,331 34,655 — 221,986 INCOME (LOSS) FROM CONTINUING OPERATIONS INCLUDING NONCONTROLLING INTERESTS 889,770 897,073 (125,241 ) 2,299,277 (363,646 ) (2,756,354 ) 840,879 (LOSS) INCOME FROM DISCONTINUED OPERATIONS, NET OF TAX — (7,303 ) — — 57,735 — 50,432 NET INCOME (LOSS) INCLUDING NONCONTROLLING INTERESTS 889,770 889,770 (125,241 ) 2,299,277 (305,911 ) (2,756,354 ) 891,311 NET INCOME ATTRIBUTABLE TO NONCONTROLLING INTERESTS — — — — (1,541 ) — (1,541 ) NET INCOME (LOSS) ATTRIBUTABLE TO TD GROUP $ 889,770 $ 889,770 $ (125,241 ) $ 2,299,277 $ (307,452 ) $ (2,756,354 ) $ 889,770 OTHER COMPREHENSIVE (LOSS) INCOME, NET OF TAX (383,081 ) (278,353 ) — 10,204 (147,493 ) 415,642 (383,081 ) TOTAL COMPREHENSIVE INCOME (LOSS) $ 506,689 $ 611,417 $ (125,241 ) $ 2,309,481 $ (454,945 ) $ (2,340,712 ) $ 506,689 TRANSDIGM GROUP INCORPORATED CONSOLIDATING STATEMENT OF INCOME AND COMPREHENSIVE INCOME FOR THE YEAR ENDED SEPTEMBER 30, 2018 (Amounts in thousands) TransDigm Group TransDigm Inc. TransDigm UK Subsidiary Guarantors Non-Guarantor Subsidiaries Eliminations Total Consolidated NET SALES $ — $ 163,348 $ — $ 3,118,032 $ 610,688 $ (80,942 ) $ 3,811,126 COST OF SALES — 94,387 — 1,253,018 367,153 (80,942 ) 1,633,616 GROSS PROFIT — 68,961 — 1,865,014 243,535 — 2,177,510 SELLING AND ADMINISTRATIVE EXPENSES — 110,405 — 425,736 (86,465 ) — 449,676 AMORTIZATION OF INTANGIBLE ASSETS — 1,261 — 62,915 8,278 — 72,454 (LOSS) INCOME FROM OPERATIONS — (42,705 ) — 1,376,363 321,722 — 1,655,380 INTEREST EXPENSE (INCOME)—NET — 678,155 6,943 1,308 (23,398 ) — 663,008 REFINANCING COSTS — 6,300 96 — — — 6,396 OTHER (INCOME) EXPENSE — (1,718 ) — (156,284 ) 158,421 — 419 EQUITY IN INCOME OF SUBSIDIARIES (957,062 ) (1,306,511 ) — — — 2,263,573 — INCOME (LOSS) FROM CONTINUING OPERATIONS BEFORE INCOME TAXES 957,062 581,069 (7,039 ) 1,531,339 186,699 (2,263,573 ) 985,557 INCOME TAX PROVISION — (375,993 ) — 379,665 20,349 — 24,021 INCOME (LOSS) FROM CONTINUING OPERATIONS INCLUDING NONCONTROLLING INTERESTS 957,062 957,062 (7,039 ) 1,151,674 166,350 (2,263,573 ) 961,536 LOSS FROM DISCONTINUED OPERATIONS, NET OF TAX — — — (2,427 ) (2,047 ) — (4,474 ) NET INCOME (LOSS) INCLUDING NONCONTROLLING INTERESTS 957,062 957,062 (7,039 ) 1,149,247 164,303 (2,263,573 ) 957,062 NET INCOME ATTRIBUTABLE TO NONCONTROLLING INTERESTS — — — — — — — NET INCOME (LOSS) ATTRIBUTABLE TO TD GROUP $ 957,062 $ 957,062 $ (7,039 ) $ 1,149,247 $ 164,303 $ (2,263,573 ) $ 957,062 OTHER COMPREHENSIVE INCOME (LOSS), NET OF TAX 89,243 95,076 — 8,491 (17,837 ) (85,730 ) 89,243 TOTAL COMPREHENSIVE INCOME (LOSS) $ 1,046,305 $ 1,052,138 $ (7,039 ) $ 1,157,738 $ 146,466 $ (2,349,303 ) $ 1,046,305 TRANSDIGM GROUP INCORPORATED CONSOLIDATING STATEMENT OF INCOME AND COMPREHENSIVE INCOME FOR THE YEAR ENDED SEPTEMBER 30, 2017 (Amounts in thousands) TransDigm Group TransDigm Inc. TransDigm UK Subsidiary Guarantors Non-Guarantor Subsidiaries Eliminations Total Consolidated NET SALES $ — $ 143,631 $ — $ 2,911,950 $ 535,129 $ (86,424 ) $ 3,504,286 COST OF SALES — 79,403 — 1,191,770 333,985 (85,499 ) 1,519,659 GROSS PROFIT — 64,228 — 1,720,180 201,144 (925 ) 1,984,627 SELLING AND ADMINISTRATIVE EXPENSES 69 99,558 — 277,083 35,845 — 412,555 AMORTIZATION OF INTANGIBLE ASSETS — 1,003 — 80,053 8,170 — 89,226 (LOSS) INCOME FROM OPERATIONS (69 ) (36,333 ) — 1,363,044 157,129 (925 ) 1,482,846 INTEREST EXPENSE (INCOME)—NET — 614,353 — (1,248 ) (10,516 ) — 602,589 REFINANCING COSTS — 39,807 — — — — 39,807 OTHER (INCOME) EXPENSE — (1,881 ) — 7,736 (2,835 ) — 3,020 EQUITY IN INCOME OF SUBSIDIARIES (596,956 ) (1,318,945 ) — — — 1,915,901 — INCOME (LOSS) FROM CONTINUING OPERATIONS BEFORE INCOME TAXES 596,887 630,333 — 1,356,556 170,480 (1,916,826 ) 837,430 INCOME TAX PROVISION — 33,377 — 156,251 19,261 — 208,889 INCOME (LOSS) FROM CONTINUING OPERATIONS INCLUDING NONCONTROLLING INTERESTS 596,887 596,956 — 1,200,305 151,219 (1,916,826 ) 628,541 LOSS FROM DISCONTINUED OPERATIONS, NET OF TAX — — — (9,496 ) (22,158 ) — (31,654 ) NET INCOME (LOSS) INCLUDING NONCONTROLLING INTERESTS 596,887 596,956 — 1,190,809 129,061 (1,916,826 ) 596,887 NET INCOME ATTRIBUTABLE TO NONCONTROLLING INTERESTS — — — — — — — NET INCOME (LOSS) ATTRIBUTABLE TO TD GROUP $ 596,887 $ 596,956 $ — $ 1,190,809 $ 129,061 $ (1,916,826 ) $ 596,887 OTHER COMPREHENSIVE INCOME (LOSS), NET OF TAX 64,644 31,603 — 16,310 58,856 (106,769 ) 64,644 TOTAL COMPREHENSIVE INCOME (LOSS) $ 661,531 $ 628,559 $ — $ 1,207,119 $ 187,917 $ (2,023,595 ) $ 661,531 TRANSDIGM GROUP INCORPORATED CONSOLIDATING STATEMENT OF CASH FLOWS FOR THE YEAR ENDED SEPTEMBER 30, 2019 (Amounts in thousands) TransDigm Group TransDigm Inc. TransDigm UK Subsidiary Guarantors Non-Guarantor Subsidiaries Eliminations Total Consolidated NET CASH (USED IN) PROVIDED BY OPERATING ACTIVITIES $ — $ (868,208 ) $ (249,794 ) $ 2,449,925 $ (327,283 ) $ 10,832 $ 1,015,472 INVESTING ACTIVITIES: Capital expenditures, net of disposals — (3,608 ) — (97,220 ) (763 ) — (101,591 ) Payments made in connection with acquisitions — (3,923,850 ) — (52,305 ) — — (3,976,155 ) Proceeds in connection with sale of discontinued operations — 188,766 — — — — 188,766 Net cash used in investing activities — (3,738,692 ) — (149,525 ) (763 ) — (3,888,980 ) FINANCING ACTIVITIES: Intercompany activities 1,629,984 21,960 250,986 (2,310,900 ) 418,802 (10,832 ) — Proceeds from exercise of stock options 81,875 — — — — — 81,875 Special dividends and dividend equivalent payments (1,712,219 ) — — — — — (1,712,219 ) Repayment on term loans — (76,428 ) — — — — (76,428 ) Proceeds from senior secured notes due 2026, net — 3,935,567 — — — — 3,935,567 Proceeds from senior subordinated notes, net — 544,248 — — — — 544,248 Cash tender and redemption of senior subordinated notes due 2020 — (550,000 ) — — — — (550,000 ) Proceeds from trade receivable securitization facility, net — — — — 49,423 — 49,423 Financing fees and other — 2,325 (1,037 ) — (2,401 ) — (1,113 ) Net cash (used in) provided by financing activities (360 ) 3,877,672 249,949 (2,310,900 ) 465,824 (10,832 ) 2,271,353 EFFECT OF EXCHANGE RATE CHANGES ON CASH AND CASH EQUIVALENTS — — — — (3,376 ) — (3,376 ) NET (DECREASE) INCREASE IN CASH AND CASH EQUIVALENTS (360 ) (729,228 ) 155 (10,500 ) 134,402 — (605,531 ) CASH AND CASH EQUIVALENTS, BEGINNING OF PERIOD 389 1,821,437 125 (1,763 ) 252,829 — 2,073,017 CASH AND CASH EQUIVALENTS, END OF PERIOD $ 29 $ 1,092,209 $ 280 $ (12,263 ) $ 387,231 $ — $ 1,467,486 TRANSDIGM GROUP INCORPORATED CONSOLIDATING STATEMENT OF CASH FLOWS FOR THE YEAR ENDED SEPTEMBER 30, 2018 (Amounts in thousands) TransDigm Group TransDigm Inc. TransDigm UK Subsidiary Guarantors Non-Guarantor Subsidiaries Eliminations Total Consolidated NET CASH (USED IN) PROVIDED BY OPERATING ACTIVITIES $ — $ (386,152 ) $ 6,598 $ 1,216,263 $ 183,290 $ 2,174 $ 1,022,173 INVESTING ACTIVITIES: Capital expenditures, net of disposals — (2,001 ) — (61,896 ) (9,444 ) — (73,341 ) Payments made in connection with acquisitions — (667,619 ) — — — — (667,619 ) Proceeds in connection with sale of discontinued operations — 57,383 — — — — 57,383 Net cash used in investing activities — (612,237 ) — (61,896 ) (9,444 ) — (683,577 ) FINANCING ACTIVITIES: Intercompany activities (3,462 ) 1,785,796 (496,081 ) (1,155,927 ) (128,152 ) (2,174 ) — Proceeds from exercise of stock options 57,583 — — — — — 57,583 Special dividends and dividend equivalent payments (56,148 ) — — — — — (56,148 ) Proceeds from term loans, net — 12,779,694 — — — — 12,779,694 Repayment on term loans — (12,174,305 ) — — — — (12,174,305 ) Proceeds from senior subordinated notes, net — — 489,608 — — — 489,608 Financing fees and other — (10,832 ) — — — — (10,832 ) Net cash (used in) provided by financing activities (2,027 ) 2,380,353 (6,473 ) (1,155,927 ) (128,152 ) (2,174 ) 1,085,600 EFFECT OF EXCHANGE RATE CHANGES ON CASH AND CASH EQUIVALENTS — — — — (1,740 ) — (1,740 ) NET (DECREASE) INCREASE IN CASH AND CASH EQUIVALENTS (2,027 ) 1,381,964 125 (1,560 ) 43,954 — 1,422,456 CASH AND CASH EQUIVALENTS, BEGINNING OF PERIOD 2,416 439,473 — (203 ) 208,875 — 650,561 CASH AND CASH EQUIVALENTS, END OF PERIOD $ 389 $ 1,821,437 $ 125 $ (1,763 ) $ 252,829 $ — $ 2,073,017 TRANSDIGM GROUP INCORPORATED CONSOLIDATING STATEMENT OF CASH FLOWS FOR THE YEAR ENDED SEPTEMBER 30, 2017 (Amounts in thousands) TransDigm Group TransDigm Inc. TransDigm UK Subsidiary Guarantors Non-Guarantor Subsidiaries Eliminations Total Consolidated NET CASH (USED IN) PROVIDED BY OPERATING ACTIVITIES $ (69 ) $ (587,800 ) $ — $ 1,334,099 $ 42,028 $ 475 $ 788,733 INVESTING ACTIVITIES: Capital expenditures, net of disposals — (1,984 ) — (63,305 ) (5,724 ) — (71,013 ) Payments made in connection with acquisitions — (215,990 ) — — — — (215,990 ) Net cash used in investing activities — (217,974 ) — (63,305 ) (5,724 ) — (287,003 ) FINANCING ACTIVITIES: Intercompany activities 2,939,121 (1,682,518 ) — (1,279,805 ) 23,677 (475 ) — Proceeds from exercise of stock options 21,177 — — — — — 21,177 Special dividends and dividend equivalent payments (2,581,552 ) — — — — — (2,581,552 ) Treasury stock purchased (389,821 ) — — — — — (389,821 ) Proceeds from term loan, net — 2,937,773 — — — — 2,937,773 Repayment on term loans — (1,284,698 ) — — — — (1,284,698 ) Proceeds from senior subordinated notes, net — 300,386 — — — — 300,386 Cash tender and redemption of senior subordinated notes due 2021, including premium — (528,847 ) — — — — (528,847 ) Proceeds from trade receivable securitization facility, net — 99,471 — — — — 99,471 Financing fees and other — (17,571 ) — — — — (17,571 ) Net cash (used in) provided by financing activities (11,075 ) (176,004 ) — (1,279,805 ) 23,677 (475 ) (1,443,682 ) EFFECT OF EXCHANGE RATE CHANGES ON CASH AND CASH EQUIVALENTS — — — — 5,519 — 5,519 NET (DECREASE) INCREASE IN CASH AND CASH EQUIVALENTS (11,144 ) (981,778 ) — (9,011 ) 65,500 — (936,433 ) CASH AND CASH EQUIVALENTS, BEGINNING OF PERIOD 13,560 1,421,251 — 8,808 143,375 — 1,586,994 CASH AND CASH EQUIVALENTS, END OF PERIOD $ 2,416 $ 439,473 $ — $ (203 ) $ 208,875 $ — $ 650,561 *****

VALUATION AND QUALIFYING ACCOUN

VALUATION AND QUALIFYING ACCOUNTS	12 Months Ended
	Sep. 30, 2019
SEC Schedule, 12-09, Valuation and Qualifying Accounts [Abstract]
VALUATION AND QUALIFYING ACCOUNTS	TRANSDIGM GROUP INCORPORATED VALUATION AND QUALIFYING ACCOUNTS FOR THE YEARS ENDED SEPTEMBER 30, 2019 , 2018 , AND 2017 (Amounts in Thousands) Column A Column B Column C Column D Column E Balance at Beginning of Period Additions Deductions from Reserve (1) Balance at End of Period Description Charged to Costs and Expenses Acquisitions Year Ended September 30, 2019 Allowance for uncollectible accounts $ 4,674 $ 5,377 $ 9,417 $ (2,066 ) $ 17,402 Inventory valuation reserves 99,351 17,148 16,980 (9,676 ) 123,803 Valuation allowance for deferred tax assets 47,249 39,651 30,760 — 117,660 Year Ended September 30, 2018 Allowance for uncollectible accounts $ 3,819 $ 1,498 $ 989 $ (1,632 ) $ 4,674 Reserve for excess and obsolete inventory 79,775 14,998 10,764 (11,039 ) 94,498 Valuation allowance for deferred tax assets 33,214 14,035 — — 47,249 Year Ended September 30, 2017 Allowance for uncollectible accounts $ 4,414 $ 1,095 $ 363 $ (2,053 ) $ 3,819 Reserve for excess and obsolete inventory 80,039 17,361 4,254 (21,879 ) 79,775 Valuation allowance for deferred tax assets 27,286 5,928 — — 33,214 (1) The amounts in this column represent charge-offs net of recoveries and the impact of foreign currency translation adjustments.

SUMMARY OF SIGNIFICANT ACCOUN_2

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Policies)	12 Months Ended
	Sep. 30, 2019
Accounting Policies [Abstract]
Basis Of Presentation And Consolidation	Basis of Presentation and Consolidation —The accompanying consolidated financial statements were prepared in conformity with generally accepted accounting principles in the United States (“GAAP”) and include the accounts of TD Group and subsidiaries. All significant intercompany balances and transactions have been eliminated. Certain reclassifications have been made to the prior year consolidated financial statements to conform to current year classifications related to the adoption of ASU 2017-07, "Compensation—Retirement Benefits (ASC 715), impacting the presentation of the net periodic benefit cost in the consolidated statements of income. The accounting pronouncement and impact of the fiscal year 2019 adoption of the pronouncement on the consolidated financial statements is summarized in Note 4, "Recent Accounting Pronouncements." The Esterline businesses were acquired during the second quarter of fiscal 2019 and preliminarily assessed as a separate segment of the Company. During the third quarter of fiscal 2019, the Esterline businesses were integrated into TransDigm's existing Power & Control, Airframe and Non-aviation segments. For financial information about our segments, see Note 17, "Segments."
Revenue Recognition and Related Allowances	Revenue Recognition —The Company adopted Accounting Standards Codification (“ASC”) 606, “Revenue from Contracts with Customers,” in the first quarter of fiscal 2019 using the modified retrospective method. The adoption of this standard did not have a material impact on our consolidated results of operations, financial position or cash flows. The results for periods before fiscal 2019 were not restated for the new standard and the cumulative effect of the change in accounting was recognized through retained earnings at the date of adoption. Refer to Note 5, "Revenue Recognition," for additional disclosures relating to ASC 606. Revenue is recognized from the sale of products when control transfers to the customer, which is demonstrated by our right to payment, a transfer of title, a transfer of the risk and rewards of ownership, or the customer acceptance, but most frequently upon shipment where the customer obtains physical possession of the goods. The majority of the Company's revenue is recorded at a point in time. Sales recognized over time are generally accounted for using an input measure to determine progress completed at the end of the period. Sales for service contracts generally are recognized as the services are provided. For agreements with multiple performance obligations, judgment is required to determine whether performance obligations specified in these agreements are distinct and should be accounted for as separate revenue transactions for recognition purposes.
Shipping and Handling Costs	Shipping and Handling Costs —Shipping and handling costs are included in cost of sales in the consolidated statements of income.
Research and Development Costs	Research and Development Costs —The Company expenses research and development costs as incurred and classifies such amounts in selling and administrative expenses. The expense recognized for research and development costs for the fiscal years ended September 30, 2019 , 2018 and 2017 was approximately $116.8 million , $73.8 million , and $73.8 million , respectively.
Cash Equivalents	Cash Equivalents —The Company considers all highly liquid investments with a maturity of three months or less when purchased to be cash equivalents.
Allowance For Uncollectible Accounts	Allowance for Uncollectible Accounts —The Company reserves for amounts determined to be uncollectible based on specific identification of losses and estimated losses based on historical experience. The allowance also incorporates a provision for the estimated impact of disputes with customers. The determination of the amount of the allowance for uncollectible accounts is subject to significant levels of judgment and estimation by management. If circumstances change or economic conditions deteriorate or improve, the allowance for uncollectible accounts could increase or decrease.
Inventories	Inventories
Property, Plant and Equipment	Property, Plant and Equipment —Property, plant and equipment are stated at cost and include improvements which significantly increase capacities or extend the useful lives of existing plant and equipment. Depreciation is computed using the straight-line method over the following estimated useful lives: land improvements from 10 to 20 years, buildings and improvements from 5 to 30 years, machinery and equipment from 2 to 10 years and furniture and fixtures from 3 to 10 years. Net gains or losses related to asset dispositions are recognized in earnings in the period in which dispositions occur. Routine maintenance, repairs and replacements are expensed as incurred. Amortization expense of assets accounted for as capital leases is included with depreciation expense. Property, plant and equipment is assessed for potential impairment whenever indicators of impairment are present by determining whether the carrying value of the property can be recovered through projected, undiscounted cash flows from future operations over the property’s remaining estimated useful life. Any impairment recognized is the amount by which the carrying amount exceeds the fair value of the asset. Fair value is measured based on quoted market prices in active markets, if available. If quoted market prices are not available, the estimate of fair value is based on various valuation techniques, including the discounted value of estimated future cash flows.
Debt Issue Costs, Premiums and Discounts	Debt Issuance Costs, Premiums and Discounts —The cost of obtaining financing as well as premiums and discounts are amortized using the effective interest method over the terms of the respective obligations as a component of interest expense within the consolidated statements of income. Debt issuance costs are presented in the consolidated balance sheets as a direct reduction from the carrying amount of the related debt liabilities.
Financial Instruments	Financial Instruments —Interest rate swap and cap agreements are used to manage interest rate risk associated with floating-rate borrowings under our credit facility. The interest rate swap and cap agreements utilized by the Company effectively modify the Company’s exposure to interest rate risk by converting a portion of the Company’s floating-rate debt to a fixed rate basis through the expiration date of the interest rate swap and cap agreements, thereby reducing the impact of interest rate changes on future interest expense. These agreements involve the receipt of floating rate amounts in exchange for fixed rate interest payments over the term of the agreements without an exchange of the underlying principal amount. These derivative instruments qualify as effective cash flow hedges under GAAP. The Company transacts business in various foreign currencies, which subjects the Company’s cash flows and earnings to exposure related to changes in foreign currency exchange rates. These exposures arise primarily from purchases or sales of products and services from third parties. Foreign currency forward exchange contracts provide for the purchase or sale of foreign currencies at specified future dates at specified exchange rates, and are used to offset changes in the fair value of certain assets or liabilities or forecasted cash flows resulting from transactions denominated in foreign currencies. For the interest rate swap and cap agreements and the foreign currency forward contracts designated as cash flow hedges, the effective portion of the gain or loss from the financial instruments was initially reported as a component of accumulated other comprehensive loss in stockholders’ deficit and subsequently reclassified into earnings in the same line as the hedged item in the same period or periods during which the hedged item affected earnings. As the interest rate swap and cap agreements are used to manage interest rate risk, any gains or losses from the derivative instruments that are reclassified into earnings are recognized in interest expense - net in the consolidated statements of income. As the foreign currency forward exchange contracts are used to manage foreign currency exposure primarily arising from purchases or sales from third parties, any gains or losses from the derivative instruments that are reclassified into earnings are recognized in cost of sales or selling and administrative expenses in the consolidated statements of income.
Intangible Assets	Goodwill and Other Intangible Assets —In accordance with ASC 805, “Business Combinations,” the Company uses the acquisition method of accounting to allocate costs of acquired businesses to the assets acquired and liabilities assumed based on their estimated fair values at the dates of acquisition. The excess costs of acquired businesses over the fair values of the assets acquired and liabilities assumed were recognized as goodwill. The valuations of the acquired assets and liabilities assumed will impact the determination of future operating results. Determining the fair value of assets acquired and liabilities assumed requires management’s judgment and often involves the use of significant estimates and assumptions, including assumptions with respect to future cash inflows and outflows, revenue growth rates, discount rates, customer attrition rates, royalty rates, asset lives and market multiples, among other items. We determine the fair values of intangible assets acquired generally in consultation with third-party valuation advisors. Fair value adjustments to the Company’s assets and liabilities are recognized and the results of operations of the acquired business are included in our consolidated financial statements from the effective date of the merger or acquisition. Intangible assets other than goodwill are recognized if the benefit of the intangible asset is obtained through contractual or other legal rights, or if the intangible asset can be sold, transferred, licensed or exchanged, regardless of the Company’s intent to do so. Goodwill is the excess of the purchase price paid over the estimated fair value of the net assets of a business acquired. Other intangible assets consist of identifiable intangibles acquired or recognized in accounting for the acquisitions (trademarks, trade names, technology, customer relationships, order backlog and other intangible assets). Goodwill and intangible assets that have indefinite useful lives (i.e., trademarks and trade names) are subject to annual impairment testing. Management determines fair value using a discounted future cash flow analysis or other accepted valuation techniques. The Company performs an annual impairment test for goodwill and other intangible assets as of the first day of the fourth fiscal quarter of each year, or more frequently, if an event occurs or circumstances change that would more likely than not reduce fair value below current value. At the time of goodwill impairment testing, the Company first assesses qualitative factors to determine whether it is more likely than not that the fair value of a reporting unit is less than its carrying amount, and whether it is therefore necessary to perform the quantitative goodwill impairment test. The quantitative goodwill impairment test consists of two steps. The first step of the goodwill impairment test, used to identify potential impairment, compares the fair value of a reporting unit (as defined) with its carrying amount, including goodwill. If the fair value of the reporting unit exceeds its carrying amount, goodwill is not considered impaired, and the second step of the goodwill impairment test is unnecessary. The second step measures the amount of impairment, if any, by comparing the carrying value of the goodwill associated with a reporting unit to the implied fair value of the goodwill derived from the estimated overall fair value of the reporting unit and the individual fair values of the other assets and liabilities of the reporting unit. GAAP requires that the annual, and any interim, impairment assessment be performed at the reporting unit level. The reporting unit level is one level below an operating segment. Substantially all goodwill was determined and recognized for each reporting unit pursuant to the accounting for the merger or acquisition as of the date of each transaction. With respect to acquisitions integrated into an existing reporting unit, any acquired goodwill is combined with the goodwill of the reporting unit. The impairment test for indefinite lived intangible assets consists of a comparison between their fair values and carrying values. If the carrying amounts of intangible assets that have indefinite useful lives exceed their fair values, an impairment loss will be recognized in an amount equal to the sum of any such excesses. The Company assesses the recoverability of its amortizable intangible assets only when indicators of impairment are present by determining whether the amortization over their remaining lives can be recovered through projected, undiscounted cash flows from future operations. Amortization of amortizable intangible assets is computed using the straight-line method over the following estimated useful lives: technology from 20 to 22 years, order backlog from 1 year to 1.5 years, customer relationships over 20 years and other intangible assets over 20 years.
Stock-Based Compensation	Stock-Based Compensation —The Company records stock-based compensation expense using the Black-Scholes pricing model based on certain valuation assumptions. Compensation expense is recorded over the vesting periods of the stock options. The Company has classified stock-based compensation primarily within selling and administrative expenses to correspond with the classification of employees that receive stock option grants. No expense is recognized for any stock options ultimately forfeited because the recipients fail to meet vesting requirements.
Income Taxes	Income Taxes —The provision for income taxes is calculated using the asset and liability method. Under the asset and liability method, deferred income taxes are recognized for the tax effect of temporary differences between the financial statement carrying amount of assets and liabilities and the amounts used for income tax purposes and for certain changes in valuation allowances. Valuation allowances are recorded to reduce certain deferred tax assets when, in our estimation, it is more likely than not that a tax benefit will not be realized.
Contingencies	Contingencies —During the ordinary course of business, the Company is from time to time threatened with, or may become a party to, legal actions and other proceedings. While the Company is currently involved in certain legal proceedings, it believes the results of these proceedings will not have a material adverse effect on its financial condition, results of operations, or cash flows.
Estimates	Estimates —The preparation of financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities at the date of the financial statements and the reported amounts of revenues and expenses during the reporting period. Actual results could differ from those estimates.
Comprehensive Income (Loss)	Comprehensive Income (Loss) —The term “comprehensive income (loss)” represents the change in stockholders’ equity (deficit) from transactions and other events and circumstances resulting from non-stockholder sources. The Company’s accumulated other comprehensive income or loss, consisting principally of fair value adjustments to its interest rate swap and cap agreements (net of tax), cumulative foreign currency translation adjustments and pension liability adjustments (net of tax), is reported separately in the accompanying consolidated statements of comprehensive income.
Foreign Currency Transactions and Translations	Foreign Currency Translation and Transactions —The assets and liabilities of subsidiaries located outside the United States are translated into U.S. dollars at the rates of exchange in effect at the balance sheet dates. Revenue and expense items are translated at the average monthly exchange rates prevailing during the period. Gains and losses resulting from foreign currency transactions are recognized currently in income, and those resulting from translation of financial statements are accumulated as a separate component of other comprehensive income (loss) for the period. Foreign currency gains or losses recognized currently in income from changes in exchange rates were immaterial to our results of operations.
Earnings per Share	Earnings per Share —Earnings per share information is determined using the two-class method, which includes the weighted-average number of common shares outstanding during the period and other securities that participate in dividends (“participating securities”). Our vested stock options are considered “participating securities” because they include non-forfeitable rights to dividends. In applying the two-class method, earnings are allocated to both common stock shares and participating securities based on their respective weighted-average shares outstanding for the period. Diluted earnings per share information may include the additional effect of other securities, if dilutive, in which case the dilutive effect of such securities is calculated using the treasury stock method. Contingently issuable shares are not included in earnings per share until the period in which the contingency is satisfied; therefore, basic and diluted earnings per share are the same.
Pension and Other Postretirement Plans, Policy [Policy Text Block]	Pension Benefits —The Company accounts for pension expense using the end of the fiscal year as our measurement date. Management selects appropriate assumptions including the discount rate, rate of increase in future compensation levels and assumed long-term rate of return on plan assets. The assumptions are based upon historical results, the current economic environment and reasonable expectations of future events. Actual results which vary from our assumptions are accumulated and amortized over future periods, and accordingly, are recognized in expense in these periods. Significant differences between the assumptions and actual experience or significant changes in assumptions could impact the pension costs and the pension obligation.

ACQUISITIONS (Tables)

ACQUISITIONS (Tables)	12 Months Ended
	Sep. 30, 2019
Esterline [Member]
Business Acquisition [Line Items]
Schedule of Recognized Identified Assets Acquired and Liabilities Assumed	Assets acquired, excluding cash: Trade accounts receivable $ 386,671 Inventories 588,741 Prepaid expenses and other current assets 421,973 Property, plant, and equipment 472,623 Other intangible assets 1,309,900 Goodwill 2,176,941 Other 22,196 Total assets acquired, excluding cash 5,379,045 Liabilities assumed: Accounts payable 144,516 Other current liabilities 717,621 Other noncurrent liabilities 593,058 Total liabilities assumed 1,455,195 Net assets acquired $ 3,923,850
Business Acquisition, Pro Forma Information [Table Text Block]	(Amounts in thousands, except per share amounts) Fiscal Year Ended September 30, 2019 September 30, 2018 Net sales $ 5,860,561 $ 5,291,760 Income from continuing operations attributable to TD Group $ 847,055 $ 551,211 Net earnings per share attributable to TD Group stockholders from continuing operations - basic and diluted $ 13.08 $ 8.90
Extant [Member]
Business Acquisition [Line Items]
Schedule of Recognized Identified Assets Acquired and Liabilities Assumed	The following table summarizes the purchase price allocation of the fair values of the assets acquired and liabilities assumed at the transaction date (presented in thousands). Assets acquired: Current assets, excluding cash acquired $ 53,325 Property, plant, and equipment 4,103 Intangible assets 105,000 Goodwill 407,046 Total assets acquired 569,474 Liabilities assumed: Current liabilities 9,876 Other noncurrent liabilities 26,453 Total liabilities assumed 36,329 Net assets acquired $ 533,145

REVENUE RECOGNITION (Tables)

REVENUE RECOGNITION (Tables)	12 Months Ended
	Sep. 30, 2019
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Contract with Customer, Asset and Liability [Table Text Block]	The cumulative effect of the changes made to our consolidated balance sheet as of October 1, 2018 for the adoption of ASC 606 were as follows (in thousands): September 30, 2018 Adjustments due to ASC 606 October 1, 2018 Assets Unbilled receivables (1) $ 10,056 $ 8,272 $ 18,328 Inventories - Net 805,292 (3,977 ) 801,315 Liabilities and Stockholders' Deficit Deferred income taxes $ 399,496 $ 1,011 $ 400,507 Accumulated deficit (2,246,578 ) 3,284 (2,243,294 ) (1) Included in prepaid expenses and other on the consolidated balance sheet.
Revenue, Initial Application Period Cumulative Effect Transition, Explanation of Change [Table Text Block]	The following table summarizes our contract assets and liabilities balances (in thousands): September 30, 2019 October 1, 2018 Change Contract assets, current (1) $ 44,097 $ 18,328 $ 25,769 Contract assets, non-current (2) 7,238 118 7,120 Total contract assets 51,335 18,446 32,889 Contract liabilities, current (3) 17,840 2,742 15,098 Contract liabilities, non-current (4) 13,234 — 13,234 Total contract liabilities 31,074 2,742 28,332 Net contract assets $ 20,261 $ 15,704 $ 4,557 (1) Included in prepaid expenses and other on the consolidated balance sheet. (2) Included in other non-current assets on the consolidated balance sheet. (3) Included in accrued liabilities on the consolidated balance sheet. (4) Included in other non-current liabilities on the consolidated balance sheet.

REVENUE RECOGNITION Contract wi

REVENUE RECOGNITION Contract with Customer, Asset and Liability (Tables)	12 Months Ended
	Sep. 30, 2019
Schedule of Contract Assets and Liabilities [Line Items]
Contract with Customer, Asset and Liability [Table Text Block]	The cumulative effect of the changes made to our consolidated balance sheet as of October 1, 2018 for the adoption of ASC 606 were as follows (in thousands): September 30, 2018 Adjustments due to ASC 606 October 1, 2018 Assets Unbilled receivables (1) $ 10,056 $ 8,272 $ 18,328 Inventories - Net 805,292 (3,977 ) 801,315 Liabilities and Stockholders' Deficit Deferred income taxes $ 399,496 $ 1,011 $ 400,507 Accumulated deficit (2,246,578 ) 3,284 (2,243,294 ) (1) Included in prepaid expenses and other on the consolidated balance sheet.

EARNINGS PER SHARE (Tables)

EARNINGS PER SHARE (Tables)	12 Months Ended
	Sep. 30, 2019
Earnings Per Share [Abstract]
Computation of Basic and Diluted Earnings Per Share	The following table sets forth the computation of basic and diluted earnings per share (in thousands, except per share data) using the two-class method: Fiscal Years Ended September 30, 2019 2018 2017 Numerator for earnings per share: Income from continuing operations including noncontrolling interests $ 840,879 $ 961,536 $ 628,541 Net income attributable to noncontrolling interests (1,541 ) — — Net income from continuing operations attributable to TD Group 839,338 961,536 628,541 Less dividends paid on participating securities (111,021 ) (56,148 ) (159,257 ) 728,317 905,388 469,284 Income (loss) from discontinued operations, net of tax 50,432 (4,474 ) (31,654 ) Net income applicable to TD Group common stock—basic and diluted $ 778,749 $ 900,914 $ 437,630 Denominator for basic and diluted earnings per share under the two-class method: Weighted-average common shares outstanding 53,091 52,345 52,517 Vested options deemed participating securities 3,174 3,252 3,013 Total shares for basic and diluted earnings per share 56,265 55,597 55,530 Net earnings per share from continuing operations—basic and diluted $ 12.94 $ 16.28 $ 8.45 Net earnings (loss) per share from discontinued operations—basic and diluted 0.90 (0.08 ) (0.57 ) Net earnings per share $ 13.84 $ 16.20 $ 7.88

TRADE ACCOUNTS RECEIVABLE (Tabl

TRADE ACCOUNTS RECEIVABLE (Tables)	12 Months Ended
	Sep. 30, 2019
Receivables [Abstract]
Content Trade Accounts Receivable	Trade accounts receivable consist of the following (in thousands): September 30, 2019 September 30, 2018 Trade accounts receivable—gross $ 1,085,005 $ 708,984 Allowance for uncollectible accounts (17,402 ) (4,674 ) Trade accounts receivable—net $ 1,067,603 $ 704,310

INVENTORIES (Tables)

INVENTORIES (Tables)	12 Months Ended
	Sep. 30, 2019
Inventory Disclosure [Abstract]
Inventories	Inventories consist of the following (in thousands): September 30, 2019 September 30, 2018 Raw materials and purchased component parts $ 804,687 $ 540,290 Work-in-progress 360,230 237,335 Finished goods 191,535 127,018 Total 1,356,452 904,643 Reserves for excess and obsolete inventory (123,803 ) (99,351 ) Inventories—Net $ 1,232,649 $ 805,292

PROPERTY, PLANT AND EQUIPMENT (

PROPERTY, PLANT AND EQUIPMENT (Tables)	12 Months Ended
	Sep. 30, 2019
Property, Plant and Equipment [Abstract]
Property, Plant and Equipment	Property, plant and equipment consist of the following (in thousands): September 30, 2019 September 30, 2018 Land and improvements $ 95,536 $ 77,455 Buildings and improvements 407,461 171,269 Machinery, equipment and other 628,096 448,014 Construction in progress 52,241 31,237 Total 1,183,334 727,975 Accumulated depreciation (426,577 ) (339,642 ) Property, plant and equipment—net $ 756,757 $ 388,333

INTANGIBLE ASSETS (Tables)

INTANGIBLE ASSETS (Tables)	12 Months Ended
	Sep. 30, 2019
Goodwill and Intangible Assets Disclosure [Abstract]
Schedule of Intangible Assets	Other intangible assets - net in the consolidated balance sheets consist of the following at September 30 (in thousands): 2019 2018 Gross Carrying Amount Accumulated Amortization Net Gross Carrying Amount Accumulated Amortization Net Trademarks and trade names $ 956,377 $ — $ 956,377 $ 799,749 $ — $ 799,749 Technology 1,805,715 496,311 1,309,404 1,347,314 416,579 930,735 Order backlog 106,889 44,603 62,286 12,200 5,409 6,791 Customer relationships 437,973 29,777 408,196 62,561 14,277 48,284 Other 16,707 9,150 7,557 10,873 8,028 2,845 Total $ 3,323,661 $ 579,841 $ 2,743,820 $ 2,232,697 $ 444,293 $ 1,788,404
Schedule of Aggregate Amortization Expense	Information regarding the amortization expense of amortizable intangible assets is detailed below (in thousands): Annual Amortization Expense: Years ended September 30, 2019 $ 134,952 2018 72,454 2017 89,226
Schedule of Finite-Lived Intangible Assets, Future Amortization	Estimated Amortization Expense: Years ending September 30, 2020 $ 182,583 2021 119,067 2022 119,067 2023 119,067 2024 119,067
Schedule of Intangible Assets Acquired	Gross Amount Amortization Period Intangible assets not subject to amortization: Goodwill $ 2,194,324 Trademarks and trade names 238,200 2,432,524 Intangible assets subject to amortization: Technology 503,500 20 years Order backlog 99,100 1.5 years Customer relationships 483,935 20 years 1,086,535 18 years Total $ 3,519,059
Summary of Changes in Carrying Value of Goodwill	The changes in the carrying amount of goodwill by segment for the fiscal years ended September 30, 2018 and 2019 were as follows (in thousands): Power & Control Airframe Non- aviation Total Balance at September 30, 2017 $ 3,269,981 $ 2,382,082 $ 93,275 $ 5,745,338 Goodwill acquired during the year (Note 2) 402,540 73,321 — 475,861 Purchase price allocation adjustments 5,354 — — 5,354 Currency translation adjustment — (3,258 ) — (3,258 ) Other (192 ) 187 — (5 ) Balance at September 30, 2018 3,677,683 2,452,332 93,275 6,223,290 Goodwill acquired during the year (Note 2) 468,613 1,179,999 545,712 2,194,324 Divestiture of goodwill acquired during the year — — (42,678 ) (42,678 ) Reclassification of goodwill acquired to assets held-for-sale (Note 23) — — (480,312 ) (480,312 ) Purchase price allocation adjustments (8,690 ) (22,901 ) — (31,591 ) Currency translation adjustment (16,422 ) (11,695 ) (14,813 ) (42,930 ) Balance at September 30, 2019 $ 4,121,184 $ 3,597,735 $ 101,184 $ 7,820,103

ACCRUED LIABILITIES (Tables)

ACCRUED LIABILITIES (Tables)	12 Months Ended
	Sep. 30, 2019
Payables and Accruals [Abstract]
Accrued Liabilities	Accrued liabilities consist of the following (in thousands): September 30, 2019 September 30, 2018 Compensation and related benefits $ 177,862 $ 81,035 Interest 92,642 96,590 Interest rate swap agreements 13,219 528 Product warranties 33,882 21,056 Dividend equivalent payments—current (see Note 18) 63,796 24,200 Environmental and other litigation reserves 12,016 31,079 Income taxes payable 44,370 9,168 Loss contract reserves 64,665 11,682 Other 173,243 76,105 Total $ 675,695 $ 351,443

DEBT (Tables)

DEBT (Tables)	12 Months Ended
	Sep. 30, 2019
Debt Disclosure [Abstract]
Schedule of Debt	The Company’s debt consists of the following (in thousands): September 30, 2019 Gross Amount Debt Issuance Costs Original Issue Discount or Premium Net Amount Short-term borrowings—trade receivable securitization facility $ 350,000 $ (481 ) $ — $ 349,519 Term loans $ 7,523,507 $ (57,744 ) $ (17,214 ) $ 7,448,549 6.00% senior subordinated notes due July 15, 2022 (2022 Notes) 1,150,000 (4,061 ) — 1,145,939 6.50% senior subordinated notes due July 15, 2024 (2024 Notes) 1,200,000 (5,690 ) — 1,194,310 6.50% senior subordinated notes due May 15, 2025 (2025 Notes) 750,000 (2,977 ) 3,090 750,113 6.375% senior subordinated notes due June 15, 2026 (6.375% 2026 Notes) 950,000 (6,790 ) — 943,210 6.875% senior subordinated notes due May 15, 2026 (6.875% 2026 Notes) 500,000 (5,532 ) (3,137 ) 491,331 6.25% secured notes due March 15, 2026 (2026 Secured Notes) 4,000,000 (59,630 ) 1,812 3,942,182 7.50% senior subordinated notes due March 15, 2027 (2027 Notes) 550,000 (5,300 ) — 544,700 Government refundable advances 39,195 — — 39,195 Capital lease obligations 49,905 — — 49,905 16,712,607 (147,724 ) (15,449 ) 16,549,434 Less current portion 80,951 (738 ) — 80,213 Long-term debt $ 16,631,656 $ (146,986 ) $ (15,449 ) $ 16,469,221 September 30, 2018 Gross Amount Debt Issuance Costs Original Issue Discount or Premium Net Amount Short-term borrowings—trade receivable securitization facility $ 300,000 $ (481 ) $ — $ 299,519 Term loans $ 7,599,932 $ (69,697 ) $ (21,030 ) $ 7,509,205 5.50% 2020 Notes 550,000 (2,187 ) — 547,813 6.00% 2022 Notes 1,150,000 (5,501 ) — 1,144,499 6.50% 2024 Notes 1,200,000 (6,866 ) — 1,193,134 6.50% 2025 Notes 750,000 (3,505 ) 3,636 750,131 6.375% 2026 Notes 950,000 (7,798 ) — 942,202 6.875% 2026 Notes 500,000 (5,616 ) (3,605 ) 490,779 12,699,932 (101,170 ) (20,999 ) 12,577,763 Less current portion 76,427 (610 ) — 75,817 Long-term debt $ 12,623,505 $ (100,560 ) $ (20,999 ) $ 12,501,946
Schedule of Term Loans	As of September 30, 2019 and 2018 , TransDigm had $7,523.5 million and $7,599.9 million in fully drawn term loans and $760 million and $600 million in revolving commitments. The term loans consist of three tranches as follows (in millions): Term Loan Facility Maturity Date Interest Rate Aggregate Principal as of September 30, 2019 2018 Tranche E May 30, 2025 LIBO rate + 2.5% $ 2,221.2 $ 2,243.7 Tranche F June 9, 2023 LIBO rate + 2.5% $ 3,524.1 $ 3,559.9 Tranche G August 22, 2024 LIBO rate + 2.5% $ 1,778.2 $ 1,796.3 The interest rates per annum applicable to all of the existing tranches of term loans are, at TransDigm’s option, equal to either an alternate base rate or an adjusted LIBO rate for one, two, three or six-month (or to the extent agreed to by each relevant lender, nine or twelve-month) interest periods chosen by TransDigm, in each case plus an applicable margin percentage. The adjusted LIBO rate is not subject to a floor. At September 30, 2019 and 2018 , the applicable interest rates for all existing tranches were 4.83% and 4.58% , respectively.
Schedule of Subordinated Borrowing [Table Text Block]	Senior Subordinated Notes
Future Maturities of Long-Term Debt	At September 30, 2019 , future maturities of long-term debt are as follows (in thousands): Fiscal years ended September 30, 2020 $ 80,951 2021 81,979 2022 (1) 1,232,200 2023 3,462,528 2024 2,933,675 Thereafter 8,921,274 $ 16,712,607

RETIREMENT PLANS RETIREMENT PLA

RETIREMENT PLANS RETIREMENT PLANS (Tables)	12 Months Ended
	Sep. 30, 2019
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Defined Benefit Plan, Assumptions [Table Text Block]	U.S. Defined Benefit Pension Plans Non-U.S. Defined Benefit Pension Plans Principal assumptions as of year end: 2019 2018 2019 2018 Discount rate 3.03% 3.96% 2.20% 2.68% Rate of increase in future compensation levels 4.48% N/A 2.98% 3.22% Assumed long-term rate of return on plan assets 6.00% 6.50% 4.16% 4.3% U.S. Post-Retirement Pension Plans Non-U.S. Post Retirement Pension Plans Principal assumptions as of year end: 2019 2018 2019 2018 Discount rate 2.86% 3.99% 2.68% N/A Initial weighted average health care trend rate 7.46% 8.50% 5.60% N/A Ultimate weighted average health care trend rate 6.00% 6.00% 4.10% N/A
Defined Benefit Plan, Plan Assets, Allocation [Table Text Block]	Allocations by investment type are as follows : Actual Plan assets allocation as of fiscal year end: Target 2019 2018 Equity securities 35 - 70% 35.1% 27.1% Debt securities 30 - 65% 59.5% 72.5% Cash —% 5.4% 0.4% Total 100.0% 100.0%
Defined Benefit Plan, Plan Assets, Category [Table Text Block]	The following table presents the fair value of the Company’s pension plan assets as of September 30, 2019 , by asset category segregated by level within the fair value hierarchy, as described in Note 20, “Fair Value Measurements” (in thousands): Fair Value Hierarchy Level 1 Level 2 Total Investments measured at fair value by category: Equity Funds: (1) U.S. Equity Securities $ 3,472 $ — $ 3,472 Non-U.S. Equity Securities 47,903 — 47,903 Fixed Income Securities: (2) Non-U.S. Foreign Commercial and Government Bonds — 86,281 86,281 Cash and Cash Equivalents (3) 29,588 — 29,588 $ 80,963 $ 86,281 $ 167,244 Investments measured at net asset value by category: (4) Equity Funds: (1) Commingled Trust Funds - Non-U.S. Securities 142,132 Fixed Income Securities: (2) U.S. Government Bonds and Securities 86,214 U.S Corporate Bonds 108,135 Non-U.S. Corporate Bonds 17,449 Non-U.S. Foreign Commercial and Government Bonds 30,330 Total $ 551,504 The following table presents the fair value of the Company’s pension plan assets as of September 30, 2018 , by asset category segregated by level within the fair value hierarchy, as described in Note 20, “Fair Value Measurements” (in thousands): Fair Value Hierarchy Level 1 Level 2 Total Investments measured at fair value by category: Equity Funds: (1) U.S. Equity Securities $ 3,545 $ — $ 3,545 Non-U.S. Equity Securities 4,959 — 4,959 Cash and Cash Equivalents (3) 295 — 295 $ 8,799 $ — $ 8,799 Investments measured at net asset value by category: (4) Equity Funds: (1) Commingled Trust Funds - Non-U.S. Securities 10,056 Fixed Income Securities: (2) U.S Corporate Bonds 3,710 Non-U.S. Corporate Bonds 16,759 Non-U.S. Foreign Commercial and Government Bonds 29,131 Total $ 68,455 (1) Level 1 Equity Securities are actively traded on U.S. and non-U.S. exchanges and are either valued using the market approach at quoted market prices on the measurement date or at the net asset value of the shares held by the plan on the measurement date based on quoted market prices. (2) Level 2 fixed income securities are primarily valued using the market approach at either quoted market prices, pricing models that use observable market data, or bids provided by independent investment brokerage firms. (3) Cash and cash equivalents include cash which is used to pay benefits and cash invested in a short-term investment fund that holds securities with values based on quoted market prices, but for which the funds are not valued on quoted market basis. (4) These investments are valued at the net asset value (“NAV”) of units held. The NAV is used to estimated fair value and is based on the fair value of the underlying investments held by the fund less its liability.
Schedule of Net Benefit Costs [Table Text Block]	Net periodic pension cost for the Company’s defined benefit plans at the end of each fiscal year consisted of the following (in thousands): Defined Benefit Pension Plans 2019 2018 2017 U.S. Pension Plans Non-U.S. Pension Plans U.S. Pension Plans Non-U.S. Pension Plans U.S. Pension Plans Non-U.S. Pension Plans Components of Net Periodic Cost Service cost $ 4,486 $ 3,486 $ 293 $ 545 $ 304 $ 760 Interest cost 7,434 4,806 778 1,798 1,064 1,721 Expected return on plan assets (10,339 ) (6,267 ) (517 ) (2,334 ) (463 ) (2,550 ) Settlements — 70 — — — — Amortization of prior service cost 62 14 36 — — — Amortization of actuarial loss (gain) 337 221 226 559 630 1,196 Amortization of transition obligation — — 209 — 314 — Net periodic cost (benefit) $ 1,980 $ 2,330 $ 1,025 $ 568 $ 1,849 $ 1,127 Post-Retirement Pension Plans 2019 2018 2017 U.S. Pension Plans Non-U.S. Pension Plans U.S. Pension Plans Non-U.S. Pension Plans U.S. Pension Plans Non-U.S. Pension Plans Components of Net Periodic Cost Service cost $ 5 $ 208 $ 5 $ — $ 5 $ — Interest cost 40 227 31 — 42 — Expected return on plan assets — — — — — — Settlements — — — — — — Amortization of prior service cost 24 — 12 — — — Amortization of actuarial (gain) loss (53 ) — (42 ) — (117 ) — Net periodic cost (benefit) $ 16 $ 435 $ 6 $ — $ (70 ) $ —
Schedule of Net Funded Status [Table Text Block]	The funded status of the defined benefit pension and post-retirement plans at the end of fiscal 2019 and 2018 were as follows (in thousands): Defined Benefit Pension Plans Post-Retirement Pension Plans September 30, 2019 September 30, 2018 September 30, 2019 September 30, 2018 U.S. Pension Plans Non-U.S. Pension Plans U.S. Pension Plans Non-U.S. Pension Plans U.S. Pension Plans Non-U.S. Pension Plans U.S. Pension Plans Non-U.S. Pension Plans Benefit Obligations Beginning balance $ 18,683 $ 72,540 $ 19,966 $ 79,495 $ 957 $ — $ 1,002 $ — Currency translation adjustment — (3,973 ) — (1,981 ) — 138 — — Service cost 4,486 3,486 277 578 5 208 5 — Interest cost 7,434 4,806 666 1,821 40 227 31 — Plan participant contributions — 380 — 60 — — — — Actuarial (gain) loss 43,368 28,127 (660 ) (5,387 ) 176 1,058 (136 ) — Acquisitions 318,161 171,377 — — 196 12,459 — — Other adjustments 440 505 — — — — 111 — Benefits paid (13,726 ) (7,239 ) (1,566 ) (2,046 ) (90 ) (315 ) (56 ) — Ending balance $ 378,846 $ 270,009 $ 18,683 $ 72,540 $ 1,284 $ 13,775 $ 957 $ — Plan Assets - Fair Value Beginning balance $ 8,655 $ 59,800 $ 8,006 $ 61,884 $ — $ — $ — $ — Currency translation adjustment — (2,719 ) — (1,572 ) — — — — Realized and unrealized gain (loss) on plan assets 30,743 18,854 582 425 — — — — Plan participants contributions — 380 — 60 — — — — Company contributions 2,300 2,726 1,633 1,049 90 315 56 — Acquisitions 289,944 162,015 — — — — — — Other adjustments — (209 ) — — — — — — Expenses paid (20 ) — — — — — — — Benefits paid (13,726 ) (7,239 ) (1,566 ) (2,046 ) (90 ) (315 ) (56 ) — Ending balance $ 317,896 $ 233,608 $ 8,655 $ 59,800 $ — $ — $ — $ — Funded Status Fair value of plan assets $ 317,896 $ 233,608 $ 8,655 $ 59,800 $ — $ — $ — $ — Benefit obligations (378,846 ) (270,009 ) (18,683 ) (72,540 ) (1,284 ) (13,775 ) (957 ) — Net amount recognized $ (60,950 ) $ (36,401 ) $ (10,028 ) $ (12,740 ) $ (1,284 ) $ (13,775 ) $ (957 ) $ — Amount Recognized on Consolidated Balance Sheet Non-current asset $ — $ 3,639 $ — $ — $ — $ — $ — $ — Current liability (2,460 ) (482 ) (841 ) (254 ) (154 ) (714 ) (88 ) — Non-current liability (58,490 ) (39,558 ) (9,187 ) (12,486 ) (1,130 ) (13,061 ) (869 ) — Net amount recognized $ (60,950 ) $ (36,401 ) $ (10,028 ) $ (12,740 ) $ (1,284 ) $ (13,775 ) $ (957 ) $ — Amounts Recognized in Accumulated Other Comprehensive Income Net actuarial loss (gain) $ 27,809 $ 23,533 $ 5,183 $ 9,416 $ (388 ) $ 1,060 $ (617 ) $ — Prior service cost 766 875 368 185 192 — 216 — Ending balance $ 28,575 $ 24,408 $ 5,551 $ 9,601 $ (196 ) $ 1,060 $ (401 ) $ —
Schedule of Expected Benefit Payments [Table Text Block]	Estimated future benefit payments expected to be paid from the pension and post-retirement benefit plans or from the Company’s assets are as follows (in thousands): Fiscal Year 2020 $ 34,275 2021 34,700 2022 35,697 2023 37,305 2024 38,059 2025 - 2029 201,998

INCOME TAXES (Tables)

INCOME TAXES (Tables)	12 Months Ended
	Sep. 30, 2019
Income Tax Disclosure [Abstract]
Schedule of Income before Income Tax, Domestic and Foreign [Table Text Block]	The Company’s income from continuing operations before income taxes includes the following components for the periods shown below (in thousands): Fiscal Years Ended September 30, 2019 2018 2017 United States $ 877,949 $ 826,539 $ 698,201 Foreign 184,916 159,018 139,229 $ 1,062,865 $ 985,557 $ 837,430
Income Tax Provision on Income Before Income Taxes	The Company’s income tax provision on income from continuing operations consists of the following for the periods shown below (in thousands): Fiscal Years Ended September 30, 2019 2018 2017 Current Federal $ 153,704 $ 136,651 $ 179,884 State 14,911 11,771 8,596 Foreign 53,720 27,239 21,327 222,335 175,661 209,807 Deferred (349 ) (151,640 ) (918 ) $ 221,986 $ 24,021 $ 208,889
Schedule of Effective Income Tax Rate Reconciliation	The differences between the income tax provision on income from continuing operations at the federal statutory income tax rate and the tax provision shown in the accompanying consolidated statements of income for the periods shown below are as follows (in thousands): Fiscal Years Ended September 30, 2019 2018 2017 Tax at statutory rate of 21% (24.5% for fiscal 2018 and 35% for fiscal 2017) $ 223,202 $ 241,853 $ 293,129 Stock compensation (57,519 ) (50,796 ) (50,314 ) Domestic manufacturing deduction — (15,091 ) (17,832 ) US tax reform (1) — (146,380 ) — Foreign rate differential 2,136 (13,770 ) (29,685 ) Foreign derived intangible income (15,886 ) — — Foreign tax credits (18,370 ) (2,939 ) — Changes in valuation allowances impacting results (2) 66,101 — — Other—net 22,322 11,144 13,591 Income tax provision $ 221,986 $ 24,021 $ 208,889
Components of Deferred Taxes	The components of the deferred taxes consist of the following at September 30 (in thousands): 2019 2018 Deferred tax liabilities: Intangible assets $ (709,561 ) $ (469,939 ) Property, plant and equipment (63,603 ) (26,615 ) Unremitted foreign earnings (7,310 ) (4,488 ) Employee benefits 122,777 73,906 U.S. interest expense limitation 64,968 — Loss contract reserves 62,513 12,670 Net operating losses 58,047 46,487 Interest rate swaps and caps 54,643 (20,052 ) Inventories 39,240 20,916 Non-U.S. income tax credits 23,746 289 U.S. income tax credits 16,850 3,114 Environmental reserves 9,636 8,551 Product warranty reserves 8,394 4,471 Other 11,338 (1,557 ) Total (308,322 ) (352,247 ) Add: Valuation allowance (117,660 ) (47,249 ) Total net deferred tax liabilities $ (425,982 ) $ (399,496 )
Reconciliation of Beginning and Ending Amount of Unrecognized Tax Benefits	A reconciliation of the beginning and ending amount of unrecognized tax benefits is as follows (in thousands): 2019 2018 Balance at October 1 $ 14,080 $ 8,655 Additions based on tax positions related to the prior year 25,936 4,637 Additions based on tax positions related to the current year 422 2,390 Reductions based on tax positions related to the prior year (2,691 ) (100 ) Settlement with tax authorities — (66 ) Lapse in statute of limitations (1,238 ) (1,436 ) Balance at September 30 $ 36,509 $ 14,080

SEGMENTS (Tables)

SEGMENTS (Tables)	12 Months Ended
	Sep. 30, 2019
Segment Reporting [Abstract]
Net Sales by Reportable Segment	The following table presents net sales by reportable segment (in thousands): Fiscal Years Ended September 30, 2019 2018 2017 Net sales to external customers Power & Control Commercial OEM $ 547,462 $ 498,654 $ 460,444 Commercial Aftermarket 710,099 665,663 606,389 Defense 1,164,545 974,818 860,411 Esterline (1) 313,468 — — Total Power & Control 2,735,574 2,139,135 1,927,244 Airframe Commercial OEM 597,765 508,671 497,612 Commercial Aftermarket 759,697 701,110 630,382 Defense 389,426 321,161 314,079 Esterline (1) 582,520 — — Total Airframe 2,329,408 1,530,942 1,442,073 Total Non-aviation 158,221 141,049 134,969 $ 5,223,203 $ 3,811,126 $ 3,504,286
EBITDA Defined by Segment to Consolidated Income Before Taxes Operations	The following table reconciles EBITDA As Defined by segment to consolidated income from continuing operations before income taxes (in thousands): Fiscal Years Ended September 30, 2019 2018 2017 EBITDA As Defined Power & Control $ 1,395,085 $ 1,114,464 $ 980,046 Airframe 1,062,679 759,253 726,630 Non-aviation 50,575 44,310 42,475 Total segment EBITDA As Defined 2,508,339 1,918,027 1,749,151 Unallocated corporate expenses 89,538 41,469 38,588 Total Company EBITDA As Defined 2,418,801 1,876,558 1,710,563 Depreciation and amortization 225,700 129,844 141,025 Interest expense - net 859,753 663,008 602,589 Acquisition-related costs 168,898 28,450 31,191 Stock compensation expense 93,362 58,481 45,524 Refinancing costs 3,013 6,396 39,807 Other, net 5,210 4,822 12,997 Income from continuing operations before income taxes $ 1,062,865 $ 985,557 $ 837,430
Capital Expenditures and Depreciation and Amortization by Segment	The following table presents capital expenditures and depreciation and amortization by segment (in thousands): Fiscal Years Ended September 30, 2019 2018 2017 Capital expenditures Power & Control $ 49,573 $ 38,762 $ 32,424 Airframe 48,027 32,028 34,526 Non-aviation 2,546 2,156 3,981 Corporate 1,445 395 82 $ 101,591 $ 73,341 $ 71,013 Depreciation and amortization Power & Control $ 98,366 $ 67,721 $ 85,681 Airframe 119,259 55,732 51,440 Non-aviation 6,280 5,276 2,745 Corporate 1,795 1,115 1,159 $ 225,700 $ 129,844 $ 141,025
Total Assets by Segment	The following table presents total assets by segment (in thousands): September 30, 2019 September 30, 2018 Total assets Power & Control $ 7,037,090 $ 5,698,524 Airframe 6,672,179 4,091,011 Non-aviation 261,841 234,770 Corporate 1,321,492 2,173,162 Assets of discontinued operations 962,129 — $ 16,254,731 $ 12,197,467

STOCK-BASED COMPENSATION (Table

STOCK-BASED COMPENSATION (Tables)	12 Months Ended
	Sep. 30, 2019
Share-based Payment Arrangement [Abstract]
Weighted Average Assumptions for all Options Granted Estimated at Grant Date Using Black-Scholes-Merton Option-Pricing Model	The fair value of the Company’s employee stock options was estimated at the date of grant using a Black-Scholes option-pricing model with the following weighted average assumptions for all options granted during the fiscal years ended: Fiscal Years Ended September 30, 2019 2018 2017 Risk-free interest rate 2.33% to 3.03% 2.01% to 2.84% 1.56% to 2.01% Expected life of options 5.5 years 5.2 years 5.0 years Expected dividend yield of stock — — — Expected volatility of stock 25% 25% 25%
Summary of Activity, Pricing and Other Information for Performance Vested Stock-Based Award Activity	The following table summarizes the activity, pricing and other information for the Company’s performance vested stock-based award activity during the fiscal year ended September 30, 2019 : Number of Options Weighted-Average Exercise Price Per Option Weighted-Average Remaining Contractual Term Aggregate Intrinsic Value Outstanding at September 30, 2018 3,878,127 $ 147.50 Granted — — Exercised (702,600 ) 107.90 Forfeited (41,505 ) 223.42 Expired — — Outstanding at September 30, 2019 3,134,022 $ 155.34 3.9 years $ 1,144,952,257 Expected to vest 141,080 $ 225.90 6.1 years $ 41,586,446 Exercisable at September 30, 2019 2,995,342 $ 152.08 3.8 years $ 1,104,053,108 September 30, 2019 : Number of Options Weighted-Average Exercise Price Per Option Weighted-Average Remaining Contractual Term Aggregate Intrinsic Value Outstanding at September 30, 2018 2,113,278 $ 283.84 Granted 1,184,680 393.32 Exercised (24,150 ) 251.22 Forfeited (105,350 ) 322.71 Expired (1,000 ) 303.90 Outstanding at September 30, 2019 3,167,458 $ 323.73 8.3 years $ 623,799,179 Expected to vest 1,820,010 $ 323.70 8.3 years $ 358,483,056 Exercisable at September 30, 2019 824,797 $ 315.16 8.2 years $ 169,504,031 September 30, 2019 : Number of Options Weighted-Average Exercise Price Per Option Weighted-Average Remaining Contractual Term Aggregate Intrinsic Value Outstanding at September 30, 2018 77,829 $ 130.09 Granted — — Exercised — — Outstanding at September 30, 2019 77,829 $ 130.09 3.1 years $ 30,398,451 Exercisable at September 30, 2019 77,829 $ 130.09 3.1 years $ 30,398,451

FAIR VALUE MEASUREMENTS (Tables

FAIR VALUE MEASUREMENTS (Tables)	12 Months Ended
	Sep. 30, 2019
Fair Value Disclosures [Abstract]
Carrying Amounts and Fair Values of Financial Instruments	The following summarizes the carrying amounts and fair values of financial instruments (in thousands): September 30, 2019 September 30, 2018 Level Carrying Amount Fair Value Carrying Amount Fair Value Assets: Cash and cash equivalents 1 $ 1,467,486 $ 1,467,486 $ 2,073,017 $ 2,073,017 Interest rate cap agreements (1) 2 1,225 1,225 36,160 36,160 Interest rate swap agreements (2) 2 — — 11,634 11,634 Interest rate swap agreements (1) 2 — — 61,126 61,126 Foreign currency forward exchange contracts (2) 2 80 80 — — Foreign currency forward exchange contracts (1) 2 21 21 — — Liabilities: Interest rate swap agreements (3) 2 13,218 13,218 528 528 Interest rate swap agreements (4) 2 202,378 202,378 142 142 Foreign currency forward exchange contracts (3) 2 6,308 6,308 — — Foreign currency forward exchange contracts (4) 2 403 403 — — Short-term borrowings - trade receivable securitization facility (5) 1 349,519 349,519 299,519 299,519 Long-term debt, including current portion: Term loans (5) 2 7,448,549 7,477,552 7,509,205 7,607,323 5.50% 2020 Notes (5) 1 — — 547,813 548,625 6.00% 2022 Notes (5) 1 1,145,939 1,167,250 1,144,499 1,155,750 6.50% 2024 Notes (5) 1 1,194,310 1,239,000 1,193,134 1,215,000 6.50% 2025 Notes (5) 1 750,113 781,875 750,131 757,500 6.375% 2026 Notes (5) 1 943,210 998,688 942,202 942,875 6.875% 2026 Notes (5) 1 491,331 535,000 490,779 507,500 6.25% 2026 Notes (5) 1 3,942,182 4,290,000 — — 7.50% 2027 Notes (5) 1 544,700 595,375 — — Government refundable advances 2 39,195 39,195 — — Capital lease obligations 2 49,906 49,906 — — (1) Included in other non-current assets on the consolidated balance sheets. (2) Included in prepaid expenses and other on the consolidated balance sheets. (3) Included in accrued liabilities on the balance sheets. (4) Included in other non-current liabilities on the consolidated balance sheet. (5)

DERIVATIVES AND HEDGING ACTIV_2

DERIVATIVES AND HEDGING ACTIVITIES (Tables)	12 Months Ended
	Sep. 30, 2019
Derivative [Line Items]
Schedule of Notional Amounts of Outstanding Derivative Positions [Table Text Block]	The following table summarizes the Company’s interest rate swap agreements: Aggregate Notional Amount (in millions) Start Date End Date Related Term Loans Conversion of Related Variable Rate Debt to Fixed Rate of: $750 3/31/2016 6/30/2020 Tranche E 5.3% (2.8% plus the 2.5% margin percentage) $500 6/29/2018 3/31/2025 Tranche E 5.5% (3.0% plus the 2.5% margin percentage) $750 6/30/2020 6/30/2022 Tranche E 5.0% (2.5% plus the 2.5% margin percentage) $1,500 6/30/2022 3/31/2025 Tranche E 5.6% (3.1% plus the 2.5% margin percentage) $1,000 6/28/2019 6/30/2021 Tranche F 4.3% (1.8% plus the 2.5% margin percentage) $1,400 6/30/2021 3/31/2023 Tranche F 5.5% (3.0% plus the 2.5% margin percentage) $500 12/30/2016 12/31/2021 Tranche G 4.4% (1.9% plus the 2.5% margin percentage) $400 9/30/2017 9/30/2022 Tranche G 4.4% (1.9% plus the 2.5% margin percentage) $900 12/31/2021 6/28/2024 Tranche G 5.6% (3.1% plus the 2.5% margin percentage) $400 9/30/2022 6/28/2024 Tranche G 5.5% (3.0% plus the 2.5% margin percentage) The following table summarizes the Company’s interest rate cap agreements: Aggregate Notional Amount Start Date End Date Related Debt Offsets Variable Rate Debt Attributable to Fluctuations Above: $750 9/30/2015 6/30/2020 Tranche E Three month LIBO rate of 2.5% $750 6/30/2020 6/30/2022 Tranche E Three month LIBO rate of 2.5% $400 6/30/2016 6/30/2021 Tranche F Three month LIBO rate of 2.0% $400 12/30/2016 12/30/2021 Tranche G Three month LIBO rate of 2.5%
Schedule of Interest Rate Derivatives	September 30, 2019 September 30, 2018 Asset Liability Asset Liability Interest rate cap agreements $ 1,225 $ — $ 36,160 $ — Interest rate swap agreements (1) — (215,596 ) 72,090 — Total 1,225 (215,596 ) 108,250 — Effect of counterparty netting — — 670 (670 ) Net derivatives as classified in the balance sheet (2) $ 1,225 $ (215,596 ) $ 108,920 $ (670 ) (1)

ACCUMULATED OTHER COMPREHENSI_2

ACCUMULATED OTHER COMPREHENSIVE LOSS (Tables)	12 Months Ended
	Sep. 30, 2019
Equity [Abstract]
Schedule of Amounts Recognized in Other Comprehensive Income (Loss) [Table Text Block]	A summary of reclassifications out of accumulated other comprehensive (loss) income for the fiscal years ended September 30, 2019 and 2018 is provided below (in thousands): Amount Reclassified Fiscal Years Ended September 30, Description of reclassifications out of accumulated other comprehensive (loss) income 2019 2018 Amortization from redesignated interest rate swap and cap agreements (1) $ 3,060 $ 3,443 Losses from settlement of foreign currency forward exchange contracts (2) (20 ) — Deferred tax expense (benefit) on reclassifications out of accumulated other comprehensive (loss) income 714 (809 ) Losses reclassified into earnings, net of tax $ 3,754 $ 2,634 (1) This component of accumulated other comprehensive (loss) income is included in interest expense (see Note 21, “Derivatives and Hedging Activities,” for additional information). (2) This component of accumulated other comprehensive (loss) income is included in net sales (see Note 21, “Derivatives and Hedging Activities,” for additional information).
Schedule of Accumulated Other Comprehensive Loss	The following table presents the components of accumulated other comprehensive (loss) income, net of taxes, for the fiscal years ended September 30, 2019 , 2018 and 2017 (in thousands): Unrealized (loss) gain on derivatives designated and qualifying as cash flow hedges (1) Defined benefit pension plan activity (2) Currency translation adjustment Total Balance at September 30, 2017 $ (26,669 ) $ (16,365 ) $ (42,109 ) $ (85,143 ) Current-period other comprehensive gain (loss) 91,226 5,636 (10,253 ) 86,609 Amounts reclassified from AOCI related to derivative instruments 2,634 — — 2,634 Net current-period other comprehensive gain (loss) 93,860 5,636 (10,253 ) 89,243 Balance at September 30, 2018 67,191 (10,729 ) (52,362 ) 4,100 Cumulative effect of ASU 2018-02, adopted October 1, 2018 (2,199 ) — — (2,199 ) Current-period other comprehensive (loss) gain (240,776 ) (29,004 ) (114,856 ) (384,636 ) Amounts reclassified from AOCI related to derivative instruments 3,754 — — 3,754 Net current-period other comprehensive (loss) gain (239,221 ) (29,004 ) (114,856 ) (383,081 ) Balance at September 30, 2019 $ (172,030 ) $ (39,733 ) $ (167,218 ) $ (378,981 ) (1) Unrealized gain (loss) represents derivative instruments, net of taxes of $69,660 , $(33,923) and $(20,663) for the fiscal years ended September 30, 2019 , 2018 and 2017 , respectively. (2) Defined benefit pension plan and other post-retirement plan activity represents pension liability adjustments, net of taxes of $8,513 , $(1,487) and $(4,130) for the fiscal years ended September 30, 2019 , 2018 and 2017 , respectively.

DISCONTINUED OPERATIONS (Tables

DISCONTINUED OPERATIONS (Tables)	12 Months Ended
	Sep. 30, 2019
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Schedule of Amounts Recognized in Other Comprehensive Income (Loss) [Table Text Block]	A summary of reclassifications out of accumulated other comprehensive (loss) income for the fiscal years ended September 30, 2019 and 2018 is provided below (in thousands): Amount Reclassified Fiscal Years Ended September 30, Description of reclassifications out of accumulated other comprehensive (loss) income 2019 2018 Amortization from redesignated interest rate swap and cap agreements (1) $ 3,060 $ 3,443 Losses from settlement of foreign currency forward exchange contracts (2) (20 ) — Deferred tax expense (benefit) on reclassifications out of accumulated other comprehensive (loss) income 714 (809 ) Losses reclassified into earnings, net of tax $ 3,754 $ 2,634 (1) This component of accumulated other comprehensive (loss) income is included in interest expense (see Note 21, “Derivatives and Hedging Activities,” for additional information). (2) This component of accumulated other comprehensive (loss) income is included in net sales (see Note 21, “Derivatives and Hedging Activities,” for additional information).
Souriau Sunbank and EIT [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Disposal Groups, Including Discontinued Operations [Table Text Block]	The following is the summarized operating results for Souriau-Sunbank and EIT for the fiscal year ended September 30, 2019 (in thousands): Fiscal Year Ended September 30, 2019 Souriau-Sunbank EIT Total Net sales $ 199,356 $ 94,619 $ 293,975 (Loss) income from discontinued operations before income taxes (17,176 ) 17,112 (64 ) Income tax benefit (expense) 14,254 (1,131 ) 13,123 (Loss) income from discontinued operations, net of tax, including noncontrolling interests (2,922 ) 15,981 13,059 Gain from sale of discontinued operations, net of tax — 37,619 37,619 Less: Income attributable to noncontrolling interests (98 ) (148 ) (246 ) (Loss) income from discontinued operations, net of tax $ (3,020 ) $ 53,452 $ 50,432
Souriau Sunbank [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Disposal Groups, Including Discontinued Operations [Table Text Block]	The following is the summarized balance sheet of Souriau-Sunbank’s assets held-for-sale and liabilities held-for-sale as of September 30, 2019 (in thousands): Assets and Liabilities of Discontinued Operations Held-for-Sale Fiscal Year Ended September 30, 2019 Cash and cash equivalents $ 28,545 Trade accounts receivable—Net 66,619 Inventories—Net 87,919 Prepaid expenses and other 1,740 Property, plant and equipment—Net 100,759 Goodwill 480,310 Other intangibles—Net 194,483 Other 1,754 Total assets of discontinued operations $ 962,129 Accounts payable $ 33,338 Accrued liabilities 55,031 Long-term debt 5,793 Deferred income taxes 41,769 Other 20,808 Total liabilities of discontinued operations $ 156,739
Schroth [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Disposal Groups, Including Discontinued Operations [Table Text Block]	The following is the summarized operating results for Schroth for the years ended September 30, 2018 and 2017 (in thousands): Fiscal Years Ended September 30, 2018 2017 Net sales $ 11,808 $ 24,590 Income (loss) from discontinued operations before income taxes 354 (5,709 ) Loss on classification as held-for-sale before income taxes — (32,000 ) Income tax benefit 2,016 6,055 Income (loss) from discontinued operations, net of tax 2,370 (31,654 ) Loss on sale of discontinued operations, net of tax (6,844 ) — Loss from discontinued operations, net of tax $ (4,474 ) $ (31,654 )

QUARTERLY FINANCIAL DATA (UNA_2

QUARTERLY FINANCIAL DATA (UNAUDTIED) (Tables)	12 Months Ended
	Sep. 30, 2019
Quarterly Financial Information Disclosure [Abstract]
Quarterly Financial Data (Unaudited)	First Quarter Second Quarter Third Quarter Fourth Quarter (in thousands, except per share amounts) Fiscal Year Ended September 30, 2019 (1) Net sales (2) $ 993,302 $ 1,167,520 $ 1,521,061 $ 1,541,320 Gross profit (2) 564,116 649,964 713,109 882,082 Income from continuing operations, net of tax (2) 196,042 200,021 127,659 317,157 Income from discontinued operations, net of tax (2) — 2,611 16,951 30,870 Net income attributable to noncontrolling interests (2) — (224 ) (160 ) (1,157 ) Net income attributable to TD Group (2) $ 196,042 $ 202,408 $ 144,450 $ 346,870 Net earnings per share from continuing operations—basic and diluted (3) $ 3.05 $ 3.55 $ 2.27 $ 4.08 Net earnings per share from discontinued operations—basic and diluted (3) — 0.05 0.30 0.55 Net earnings per share (3) $ 3.05 $ 3.60 $ 2.57 $ 4.63 First Quarter Second Quarter Third Quarter Fourth Quarter (in thousands, except per share amounts) Fiscal Year Ended September 30, 2018 (1) Net sales (2) $ 847,960 $ 933,070 $ 980,662 $ 1,049,434 Gross profit (2) 476,650 534,074 569,520 597,266 Income from continuing operations, net of tax (2) 312,011 201,840 217,391 230,294 Income (loss) from discontinued operations, net of tax (2) 2,764 (5,562 ) (145 ) (1,531 ) Net income attributable to TD Group (2) $ 314,775 $ 196,278 $ 217,246 $ 228,763 Net earnings per share from continuing operations—basic and diluted (3) $ 4.60 $ 3.63 $ 3.91 $ 4.14 Net earnings (loss) per share from discontinued operations—basic and diluted (3) 0.05 (0.10 ) — (0.03 ) Net earnings per share (3) $ 4.65 $ 3.53 $ 3.91 $ 4.11 (1) Results adjusted to reflect amounts reclassified to discontinued operations due to the Company’s classification of Souriau-Sunbank and EIT at September 30, 2019, and Schroth at September 30, 2017, as discontinued operations. See Note 23, “Discontinued Operations,” for additional information. (2) The Company’s operating results include the results of operations of acquisitions from the effective date of each acquisition. See Note 2 “Acquisitions and Divestitures,” for additional details. (3) The sum of the earnings per share for the four quarters in a year does not necessarily equal the total year earnings per share due to the weighted average number of shares outstanding in each quarter.

SUPPLEMENTAL GUARANTOR INFORM_2

SUPPLEMENTAL GUARANTOR INFORMATION (Tables)	12 Months Ended
	Sep. 30, 2019
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Supplemental Condensed Consolidating Balance Sheet	TRANSDIGM GROUP INCORPORATED CONSOLIDATING BALANCE SHEET AS OF SEPTEMBER 30, 2019 (Amounts in thousands) TransDigm Group TransDigm Inc. Transdigm UK Subsidiary Guarantors Non-Guarantor Subsidiaries Eliminations Total Consolidated ASSETS CURRENT ASSETS: Cash and cash equivalents $ 29 $ 1,092,209 $ 280 $ (12,263 ) $ 387,231 $ — $ 1,467,486 Trade accounts receivable—Net — — — 172,099 895,504 — 1,067,603 Inventories—Net — 52,291 — 879,681 315,966 (15,289 ) 1,232,649 Assets held-for-sale — — — 206,419 755,710 — 962,129 Prepaid expenses and other — 27,175 — 45,220 62,985 — 135,380 Total current assets 29 1,171,675 280 1,291,156 2,417,396 (15,289 ) 4,865,247 INVESTMENT IN SUBSIDIARIES AND INTERCOMPANY BALANCES (2,894,934 ) 14,729,513 974,663 16,373,195 6,898,707 (36,081,144 ) — PROPERTY, PLANT AND EQUIPMENT—NET — 16,971 — 513,337 226,449 — 756,757 GOODWILL — 82,924 — 5,544,529 2,192,650 — 7,820,103 OTHER INTANGIBLE ASSETS—NET — 25,444 — 2,063,944 654,432 — 2,743,820 OTHER — 5,364 — 33,931 29,509 — 68,804 TOTAL ASSETS $ (2,894,905 ) $ 16,031,891 $ 974,943 $ 25,820,092 $ 12,419,143 $ (36,096,433 ) $ 16,254,731 LIABILITIES AND STOCKHOLDERS’ EQUITY (DEFICIT) CURRENT LIABILITIES: Current portion of long-term debt $ — $ 75,688 $ — $ 1,020 $ 3,505 $ — $ 80,213 Short-term borrowings—trade receivable securitization facility — — — — 349,519 — 349,519 Accounts payable — 16,517 — 160,793 99,280 — 276,590 Accrued liabilities — 215,562 12,892 237,026 210,215 — 675,695 Liabilities held-for-sale — — — 22,306 134,433 — 156,739 Total current liabilities — 307,767 12,892 421,145 796,952 — 1,538,756 LONG-TERM DEBT — 15,893,314 491,331 49,240 35,336 — 16,469,221 DEFERRED INCOME TAXES — — — 346,456 94,361 — 440,817 OTHER NON-CURRENT LIABILITIES — 315,262 — 232,520 143,238 — 691,020 Total liabilities — 16,516,343 504,223 1,049,361 1,069,887 — 19,139,814 TD GROUP STOCKHOLDERS’ (DEFICIT) EQUITY (2,894,905 ) (484,452 ) 470,720 24,770,731 11,339,434 (36,096,433 ) (2,894,905 ) NONCONTROLLING INTEREST — — — — 9,822 — 9,822 TOTAL LIABILITIES AND STOCKHOLDERS’ (DEFICIT) EQUITY $ (2,894,905 ) $ 16,031,891 $ 974,943 $ 25,820,092 $ 12,419,143 $ (36,096,433 ) $ 16,254,731 TRANSDIGM GROUP INCORPORATED CONSOLIDATING BALANCE SHEET AS OF SEPTEMBER 30, 2018 (Amounts in thousands) TransDigm Group TransDigm Inc. TransDigm UK Subsidiary Guarantors Non-Guarantor Subsidiaries Eliminations Total Consolidated ASSETS CURRENT ASSETS: Cash and cash equivalents $ 389 $ 1,821,437 $ 125 $ (1,763 ) $ 252,829 $ — $ 2,073,017 Trade accounts receivable—Net — — — 40,916 663,394 — 704,310 Inventories—Net — 45,262 — 648,574 115,913 (4,457 ) 805,292 Prepaid expenses and other — 16,231 — 47,020 11,417 — 74,668 Total current assets 389 1,882,930 125 734,747 1,043,553 (4,457 ) 3,657,287 INVESTMENT IN SUBSIDIARIES AND INTERCOMPANY BALANCES (1,808,860 ) 10,459,497 1,099,886 8,928,726 2,160,236 (20,839,485 ) — PROPERTY, PLANT AND EQUIPMENT—NET — 15,562 — 319,567 53,204 — 388,333 GOODWILL — 97,002 — 5,466,148 660,140 — 6,223,290 OTHER INTANGIBLE ASSETS—NET — 31,362 — 1,514,983 242,059 — 1,788,404 OTHER — 104,633 — 29,805 5,715 — 140,153 TOTAL ASSETS $ (1,808,471 ) $ 12,590,986 $ 1,100,011 $ 16,993,976 $ 4,164,907 $ (20,843,942 ) $ 12,197,467 LIABILITIES AND STOCKHOLDERS’ EQUITY (DEFICIT) CURRENT LIABILITIES: Current portion of long-term debt $ — $ 75,817 $ — $ — $ — $ — $ 75,817 Short-term borrowings—trade receivable securitization facility — — — — 299,519 — 299,519 Accounts payable — 18,470 — 115,735 39,398 — 173,603 Accrued liabilities — 118,600 13,274 162,618 56,951 — 351,443 Total current liabilities — 212,887 13,274 278,353 395,868 — 900,382 LONG-TERM DEBT — 12,011,166 490,780 — — — 12,501,946 DEFERRED INCOME TAXES — 345,357 — (2,329 ) 56,468 — 399,496 OTHER NON-CURRENT LIABILITIES — 77,573 — 104,829 21,712 — 204,114 Total liabilities — 12,646,983 504,054 380,853 474,048 — 14,005,938 TD GROUP STOCKHOLDERS’ (DEFICIT) EQUITY (1,808,471 ) (55,997 ) 595,957 16,613,123 3,690,859 (20,843,942 ) (1,808,471 ) NONCONTROLLING INTEREST — — — — — — — TOTAL LIABILITIES AND STOCKHOLDERS’ (DEFICIT) EQUITY $ (1,808,471 ) $ 12,590,986 $ 1,100,011 $ 16,993,976 $ 4,164,907 $ (20,843,942 ) $ 12,197,467
Supplemental Condensed Consolidating Statement of Income and Comprehensive Income	TRANSDIGM GROUP INCORPORATED CONSOLIDATING STATEMENT OF INCOME AND COMPREHENSIVE INCOME FOR THE YEAR ENDED SEPTEMBER 30, 2019 (Amounts in thousands) TransDigm Group TransDigm Inc. TransDigm UK Subsidiary Guarantors Non-Guarantor Subsidiaries Eliminations Total Consolidated NET SALES $ — $ 186,360 $ — $ 4,103,848 $ 1,105,379 $ (172,384 ) $ 5,223,203 COST OF SALES — 109,414 — 1,771,217 705,685 (172,384 ) 2,413,932 GROSS PROFIT — 76,946 — 2,332,631 399,694 — 2,809,271 SELLING AND ADMINISTRATIVE EXPENSES — 258,465 14 348,928 140,366 — 747,773 AMORTIZATION OF INTANGIBLE ASSETS — 925 — 98,868 35,159 — 134,952 (LOSS) INCOME FROM OPERATIONS — (182,444 ) (14 ) 1,884,835 224,169 — 1,926,546 INTEREST EXPENSE (INCOME)—NET — 855,325 35,420 (11,638 ) (19,354 ) — 859,753 REFINANCING COSTS — 2,745 268 — — — 3,013 OTHER (INCOME) EXPENSE — (71,003 ) 89,539 (590,135 ) 572,514 — 915 EQUITY IN INCOME OF SUBSIDIARIES (889,770 ) (1,866,584 ) — — — 2,756,354 — INCOME (LOSS) FROM CONTINUING OPERATIONS BEFORE INCOME TAXES 889,770 897,073 (125,241 ) 2,486,608 (328,991 ) (2,756,354 ) 1,062,865 INCOME TAX PROVISION — — — 187,331 34,655 — 221,986 INCOME (LOSS) FROM CONTINUING OPERATIONS INCLUDING NONCONTROLLING INTERESTS 889,770 897,073 (125,241 ) 2,299,277 (363,646 ) (2,756,354 ) 840,879 (LOSS) INCOME FROM DISCONTINUED OPERATIONS, NET OF TAX — (7,303 ) — — 57,735 — 50,432 NET INCOME (LOSS) INCLUDING NONCONTROLLING INTERESTS 889,770 889,770 (125,241 ) 2,299,277 (305,911 ) (2,756,354 ) 891,311 NET INCOME ATTRIBUTABLE TO NONCONTROLLING INTERESTS — — — — (1,541 ) — (1,541 ) NET INCOME (LOSS) ATTRIBUTABLE TO TD GROUP $ 889,770 $ 889,770 $ (125,241 ) $ 2,299,277 $ (307,452 ) $ (2,756,354 ) $ 889,770 OTHER COMPREHENSIVE (LOSS) INCOME, NET OF TAX (383,081 ) (278,353 ) — 10,204 (147,493 ) 415,642 (383,081 ) TOTAL COMPREHENSIVE INCOME (LOSS) $ 506,689 $ 611,417 $ (125,241 ) $ 2,309,481 $ (454,945 ) $ (2,340,712 ) $ 506,689 TRANSDIGM GROUP INCORPORATED CONSOLIDATING STATEMENT OF INCOME AND COMPREHENSIVE INCOME FOR THE YEAR ENDED SEPTEMBER 30, 2018 (Amounts in thousands) TransDigm Group TransDigm Inc. TransDigm UK Subsidiary Guarantors Non-Guarantor Subsidiaries Eliminations Total Consolidated NET SALES $ — $ 163,348 $ — $ 3,118,032 $ 610,688 $ (80,942 ) $ 3,811,126 COST OF SALES — 94,387 — 1,253,018 367,153 (80,942 ) 1,633,616 GROSS PROFIT — 68,961 — 1,865,014 243,535 — 2,177,510 SELLING AND ADMINISTRATIVE EXPENSES — 110,405 — 425,736 (86,465 ) — 449,676 AMORTIZATION OF INTANGIBLE ASSETS — 1,261 — 62,915 8,278 — 72,454 (LOSS) INCOME FROM OPERATIONS — (42,705 ) — 1,376,363 321,722 — 1,655,380 INTEREST EXPENSE (INCOME)—NET — 678,155 6,943 1,308 (23,398 ) — 663,008 REFINANCING COSTS — 6,300 96 — — — 6,396 OTHER (INCOME) EXPENSE — (1,718 ) — (156,284 ) 158,421 — 419 EQUITY IN INCOME OF SUBSIDIARIES (957,062 ) (1,306,511 ) — — — 2,263,573 — INCOME (LOSS) FROM CONTINUING OPERATIONS BEFORE INCOME TAXES 957,062 581,069 (7,039 ) 1,531,339 186,699 (2,263,573 ) 985,557 INCOME TAX PROVISION — (375,993 ) — 379,665 20,349 — 24,021 INCOME (LOSS) FROM CONTINUING OPERATIONS INCLUDING NONCONTROLLING INTERESTS 957,062 957,062 (7,039 ) 1,151,674 166,350 (2,263,573 ) 961,536 LOSS FROM DISCONTINUED OPERATIONS, NET OF TAX — — — (2,427 ) (2,047 ) — (4,474 ) NET INCOME (LOSS) INCLUDING NONCONTROLLING INTERESTS 957,062 957,062 (7,039 ) 1,149,247 164,303 (2,263,573 ) 957,062 NET INCOME ATTRIBUTABLE TO NONCONTROLLING INTERESTS — — — — — — — NET INCOME (LOSS) ATTRIBUTABLE TO TD GROUP $ 957,062 $ 957,062 $ (7,039 ) $ 1,149,247 $ 164,303 $ (2,263,573 ) $ 957,062 OTHER COMPREHENSIVE INCOME (LOSS), NET OF TAX 89,243 95,076 — 8,491 (17,837 ) (85,730 ) 89,243 TOTAL COMPREHENSIVE INCOME (LOSS) $ 1,046,305 $ 1,052,138 $ (7,039 ) $ 1,157,738 $ 146,466 $ (2,349,303 ) $ 1,046,305 TRANSDIGM GROUP INCORPORATED CONSOLIDATING STATEMENT OF INCOME AND COMPREHENSIVE INCOME FOR THE YEAR ENDED SEPTEMBER 30, 2017 (Amounts in thousands) TransDigm Group TransDigm Inc. TransDigm UK Subsidiary Guarantors Non-Guarantor Subsidiaries Eliminations Total Consolidated NET SALES $ — $ 143,631 $ — $ 2,911,950 $ 535,129 $ (86,424 ) $ 3,504,286 COST OF SALES — 79,403 — 1,191,770 333,985 (85,499 ) 1,519,659 GROSS PROFIT — 64,228 — 1,720,180 201,144 (925 ) 1,984,627 SELLING AND ADMINISTRATIVE EXPENSES 69 99,558 — 277,083 35,845 — 412,555 AMORTIZATION OF INTANGIBLE ASSETS — 1,003 — 80,053 8,170 — 89,226 (LOSS) INCOME FROM OPERATIONS (69 ) (36,333 ) — 1,363,044 157,129 (925 ) 1,482,846 INTEREST EXPENSE (INCOME)—NET — 614,353 — (1,248 ) (10,516 ) — 602,589 REFINANCING COSTS — 39,807 — — — — 39,807 OTHER (INCOME) EXPENSE — (1,881 ) — 7,736 (2,835 ) — 3,020 EQUITY IN INCOME OF SUBSIDIARIES (596,956 ) (1,318,945 ) — — — 1,915,901 — INCOME (LOSS) FROM CONTINUING OPERATIONS BEFORE INCOME TAXES 596,887 630,333 — 1,356,556 170,480 (1,916,826 ) 837,430 INCOME TAX PROVISION — 33,377 — 156,251 19,261 — 208,889 INCOME (LOSS) FROM CONTINUING OPERATIONS INCLUDING NONCONTROLLING INTERESTS 596,887 596,956 — 1,200,305 151,219 (1,916,826 ) 628,541 LOSS FROM DISCONTINUED OPERATIONS, NET OF TAX — — — (9,496 ) (22,158 ) — (31,654 ) NET INCOME (LOSS) INCLUDING NONCONTROLLING INTERESTS 596,887 596,956 — 1,190,809 129,061 (1,916,826 ) 596,887 NET INCOME ATTRIBUTABLE TO NONCONTROLLING INTERESTS — — — — — — — NET INCOME (LOSS) ATTRIBUTABLE TO TD GROUP $ 596,887 $ 596,956 $ — $ 1,190,809 $ 129,061 $ (1,916,826 ) $ 596,887 OTHER COMPREHENSIVE INCOME (LOSS), NET OF TAX 64,644 31,603 — 16,310 58,856 (106,769 ) 64,644 TOTAL COMPREHENSIVE INCOME (LOSS) $ 661,531 $ 628,559 $ — $ 1,207,119 $ 187,917 $ (2,023,595 ) $ 661,531
Supplemental Condensed Consolidating Statement of Cash Flows	TRANSDIGM GROUP INCORPORATED CONSOLIDATING STATEMENT OF CASH FLOWS FOR THE YEAR ENDED SEPTEMBER 30, 2019 (Amounts in thousands) TransDigm Group TransDigm Inc. TransDigm UK Subsidiary Guarantors Non-Guarantor Subsidiaries Eliminations Total Consolidated NET CASH (USED IN) PROVIDED BY OPERATING ACTIVITIES $ — $ (868,208 ) $ (249,794 ) $ 2,449,925 $ (327,283 ) $ 10,832 $ 1,015,472 INVESTING ACTIVITIES: Capital expenditures, net of disposals — (3,608 ) — (97,220 ) (763 ) — (101,591 ) Payments made in connection with acquisitions — (3,923,850 ) — (52,305 ) — — (3,976,155 ) Proceeds in connection with sale of discontinued operations — 188,766 — — — — 188,766 Net cash used in investing activities — (3,738,692 ) — (149,525 ) (763 ) — (3,888,980 ) FINANCING ACTIVITIES: Intercompany activities 1,629,984 21,960 250,986 (2,310,900 ) 418,802 (10,832 ) — Proceeds from exercise of stock options 81,875 — — — — — 81,875 Special dividends and dividend equivalent payments (1,712,219 ) — — — — — (1,712,219 ) Repayment on term loans — (76,428 ) — — — — (76,428 ) Proceeds from senior secured notes due 2026, net — 3,935,567 — — — — 3,935,567 Proceeds from senior subordinated notes, net — 544,248 — — — — 544,248 Cash tender and redemption of senior subordinated notes due 2020 — (550,000 ) — — — — (550,000 ) Proceeds from trade receivable securitization facility, net — — — — 49,423 — 49,423 Financing fees and other — 2,325 (1,037 ) — (2,401 ) — (1,113 ) Net cash (used in) provided by financing activities (360 ) 3,877,672 249,949 (2,310,900 ) 465,824 (10,832 ) 2,271,353 EFFECT OF EXCHANGE RATE CHANGES ON CASH AND CASH EQUIVALENTS — — — — (3,376 ) — (3,376 ) NET (DECREASE) INCREASE IN CASH AND CASH EQUIVALENTS (360 ) (729,228 ) 155 (10,500 ) 134,402 — (605,531 ) CASH AND CASH EQUIVALENTS, BEGINNING OF PERIOD 389 1,821,437 125 (1,763 ) 252,829 — 2,073,017 CASH AND CASH EQUIVALENTS, END OF PERIOD $ 29 $ 1,092,209 $ 280 $ (12,263 ) $ 387,231 $ — $ 1,467,486 TRANSDIGM GROUP INCORPORATED CONSOLIDATING STATEMENT OF CASH FLOWS FOR THE YEAR ENDED SEPTEMBER 30, 2018 (Amounts in thousands) TransDigm Group TransDigm Inc. TransDigm UK Subsidiary Guarantors Non-Guarantor Subsidiaries Eliminations Total Consolidated NET CASH (USED IN) PROVIDED BY OPERATING ACTIVITIES $ — $ (386,152 ) $ 6,598 $ 1,216,263 $ 183,290 $ 2,174 $ 1,022,173 INVESTING ACTIVITIES: Capital expenditures, net of disposals — (2,001 ) — (61,896 ) (9,444 ) — (73,341 ) Payments made in connection with acquisitions — (667,619 ) — — — — (667,619 ) Proceeds in connection with sale of discontinued operations — 57,383 — — — — 57,383 Net cash used in investing activities — (612,237 ) — (61,896 ) (9,444 ) — (683,577 ) FINANCING ACTIVITIES: Intercompany activities (3,462 ) 1,785,796 (496,081 ) (1,155,927 ) (128,152 ) (2,174 ) — Proceeds from exercise of stock options 57,583 — — — — — 57,583 Special dividends and dividend equivalent payments (56,148 ) — — — — — (56,148 ) Proceeds from term loans, net — 12,779,694 — — — — 12,779,694 Repayment on term loans — (12,174,305 ) — — — — (12,174,305 ) Proceeds from senior subordinated notes, net — — 489,608 — — — 489,608 Financing fees and other — (10,832 ) — — — — (10,832 ) Net cash (used in) provided by financing activities (2,027 ) 2,380,353 (6,473 ) (1,155,927 ) (128,152 ) (2,174 ) 1,085,600 EFFECT OF EXCHANGE RATE CHANGES ON CASH AND CASH EQUIVALENTS — — — — (1,740 ) — (1,740 ) NET (DECREASE) INCREASE IN CASH AND CASH EQUIVALENTS (2,027 ) 1,381,964 125 (1,560 ) 43,954 — 1,422,456 CASH AND CASH EQUIVALENTS, BEGINNING OF PERIOD 2,416 439,473 — (203 ) 208,875 — 650,561 CASH AND CASH EQUIVALENTS, END OF PERIOD $ 389 $ 1,821,437 $ 125 $ (1,763 ) $ 252,829 $ — $ 2,073,017 TRANSDIGM GROUP INCORPORATED CONSOLIDATING STATEMENT OF CASH FLOWS FOR THE YEAR ENDED SEPTEMBER 30, 2017 (Amounts in thousands) TransDigm Group TransDigm Inc. TransDigm UK Subsidiary Guarantors Non-Guarantor Subsidiaries Eliminations Total Consolidated NET CASH (USED IN) PROVIDED BY OPERATING ACTIVITIES $ (69 ) $ (587,800 ) $ — $ 1,334,099 $ 42,028 $ 475 $ 788,733 INVESTING ACTIVITIES: Capital expenditures, net of disposals — (1,984 ) — (63,305 ) (5,724 ) — (71,013 ) Payments made in connection with acquisitions — (215,990 ) — — — — (215,990 ) Net cash used in investing activities — (217,974 ) — (63,305 ) (5,724 ) — (287,003 ) FINANCING ACTIVITIES: Intercompany activities 2,939,121 (1,682,518 ) — (1,279,805 ) 23,677 (475 ) — Proceeds from exercise of stock options 21,177 — — — — — 21,177 Special dividends and dividend equivalent payments (2,581,552 ) — — — — — (2,581,552 ) Treasury stock purchased (389,821 ) — — — — — (389,821 ) Proceeds from term loan, net — 2,937,773 — — — — 2,937,773 Repayment on term loans — (1,284,698 ) — — — — (1,284,698 ) Proceeds from senior subordinated notes, net — 300,386 — — — — 300,386 Cash tender and redemption of senior subordinated notes due 2021, including premium — (528,847 ) — — — — (528,847 ) Proceeds from trade receivable securitization facility, net — 99,471 — — — — 99,471 Financing fees and other — (17,571 ) — — — — (17,571 ) Net cash (used in) provided by financing activities (11,075 ) (176,004 ) — (1,279,805 ) 23,677 (475 ) (1,443,682 ) EFFECT OF EXCHANGE RATE CHANGES ON CASH AND CASH EQUIVALENTS — — — — 5,519 — 5,519 NET (DECREASE) INCREASE IN CASH AND CASH EQUIVALENTS (11,144 ) (981,778 ) — (9,011 ) 65,500 — (936,433 ) CASH AND CASH EQUIVALENTS, BEGINNING OF PERIOD 13,560 1,421,251 — 8,808 143,375 — 1,586,994 CASH AND CASH EQUIVALENTS, END OF PERIOD $ 2,416 $ 439,473 $ — $ (203 ) $ 208,875 $ — $ 650,561

DESCRIPTION OF THE BUSINESS - N

DESCRIPTION OF THE BUSINESS - Narratives (Detail)	Sep. 30, 2019
Accounting Policies [Abstract]
Noncontrolling Interest, Ownership Percentage by Parent	100.00%

ACQUISITIONS - Narratives (Deta

ACQUISITIONS - Narratives (Detail) - USD ($) $ / shares in Units, $ in Thousands	Sep. 20, 2019	Aug. 30, 2019	Mar. 14, 2019	Oct. 01, 2018	Jul. 13, 2018	Apr. 24, 2018	Mar. 15, 2018	Jan. 26, 2018	Feb. 22, 2017	Mar. 31, 2018	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2017
Business Acquisition [Line Items]
Goodwill											$ 7,820,103	$ 6,223,290	$ 5,745,338
Loss Contingency, Accrual, Current											64,665	11,682
Payments to Acquire Businesses, Net of Cash Acquired											3,976,155	667,619	215,990
NET SALES											5,223,203	3,811,126	3,504,286
INCOME FROM CONTINUING OPERATIONS INCLUDING NONCONTROLLING INTERESTS											840,879	961,536	628,541
AMORTIZATION OF INTANGIBLE ASSETS											134,952	72,454	89,226
Amortization of inventory step-up											76,927	7,080	20,621
Interest Income (Expense), Net											$ (859,753)	(663,008)	(602,589)
Minimum
Business Acquisition [Line Items]
Estimated useful life of aircraft (in years)											25 years
Maximum
Business Acquisition [Line Items]
Estimated useful life of aircraft (in years)											30 years
Esterline [Member]
Business Acquisition [Line Items]
Preliminary Property Amortization											$ 14,400
Preliminary Inventory Step-up			$ 71,400
Goodwill			2,176,941
Loss Contingency Accrual			268,400								231,800
Loss Contingency, Accrual, Current											60,000
Loss Contingency, Accrual, Noncurrent											171,800
Loss Contingency Accrual, Period Increase (Decrease)											27,300
Amount of goodwill expected to be tax deductible			$ 25,600
Business Acquisition, Share Price			$ 122.50
Payments to Acquire Businesses, Net of Cash Acquired			$ 3,536,300
Interest Expense											163,500
Interest income											8,200
Preliminary intangible asset amortization											71,500	103,300
Business acquisition, assumption of net indebtedness			1,455,195
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Cash and Equivalents			398,200
Business Combination, Recognized Identifiable Assets Acquired, Goodwill, and Liabilities Assumed, Net			3,923,850
Restricted Cash, Current			387,600
Business acquisition, Intangibles, Tax Deductible Amount			48,900
Intangible assets			$ 1,309,900
NET SALES											908,000
INCOME FROM CONTINUING OPERATIONS INCLUDING NONCONTROLLING INTERESTS											57,100
AMORTIZATION OF INTANGIBLE ASSETS											55,400
Amortization of inventory step-up											71,400
Business Combination, Acquisition Related Costs											85,100
Interest Income (Expense), Net											155,300
Souriau Sunbank [Member]
Business Acquisition [Line Items]
Loss Contingency Accrual											9,300
Skandia [Member]
Business Acquisition [Line Items]
Business Acquisition Purchase Price Adjustment												200
Payments to Acquire Businesses, Net of Cash Acquired					$ 84,300
Extant [Member]
Business Acquisition [Line Items]
Goodwill						$ 407,046
Tax benefit recognition period (in years)						15 years
Amount of goodwill expected to be tax deductible						$ 12,400
Business Acquisition Purchase Price Adjustment												200
Payments to Acquire Businesses, Net of Cash Acquired						533,100
Business acquisition, assumption of net indebtedness						36,329
Business Combination, Recognized Identifiable Assets Acquired, Goodwill, and Liabilities Assumed, Net						533,145
Business acquisition, Intangibles, Tax Deductible Amount						62,500
Intangible assets						$ 105,000
Kirkhill [Member]
Business Acquisition [Line Items]
Business Acquisition Purchase Price Adjustment												600
Payments to Acquire Businesses, Net of Cash Acquired							$ 49,300
Third Quarter 2017 Acquisitions [Member]
Business Acquisition [Line Items]
Tax benefit recognition period (in years)										15 years
Amount of goodwill expected to be tax deductible												66,000
Business Acquisition Purchase Price Adjustment										$ 1,000
Business Acquisition, Goodwill, Expected Nondeductible Tax Amount												9,000
Payments to Acquire Businesses, Net of Cash Acquired										$ 106,700
Schroth [Member]
Business Acquisition [Line Items]
Business Combination, Consideration Transferred									$ 89,700
Business Acquisition Purchase Price Adjustment												300
Payments to Acquire Businesses, Net of Cash Acquired									79,700
Business Combination, Consideration Transferred, Liabilities Incurred									$ 9,000		8,500
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Noncurrent Liabilities											500
Stormscope [Member]
Business Acquisition [Line Items]
Tax benefit recognition period (in years)		15 years
Amount of goodwill expected to be tax deductible		$ 11,100
Payments to Acquire Businesses, Net of Cash Acquired		20,000
Business acquisition, Intangibles, Tax Deductible Amount		$ 7,500
NavCom [Member]
Business Acquisition [Line Items]
Tax benefit recognition period (in years)				15 years
Amount of goodwill expected to be tax deductible				$ 9,000
Payments to Acquire Businesses, Net of Cash Acquired				$ 27,000
Souriau Sunbank [Member]
Business Acquisition [Line Items]
Divestiture, Sale Price											920,000
NET SALES											$ 199,356
Esterline Interface Technology Group [Member]
Business Acquisition [Line Items]
Divestiture, Sale Price	$ 190,000
Schroth [Member]
Business Acquisition [Line Items]
Divestiture, Sale Price								$ 61,400				61,400
NET SALES												$ 11,808	$ 24,590

ACQUISITIONS - Schedule of Reco

ACQUISITIONS - Schedule of Recognized Identified Assets Acquired and Liabilities Assumed (Details) - USD ($) $ in Thousands	Sep. 30, 2019	Mar. 14, 2019	Sep. 30, 2018	Apr. 24, 2018	Sep. 30, 2017
Business Acquisition [Line Items]
Goodwill	$ 7,820,103		$ 6,223,290		$ 5,745,338
Esterline [Member]
Business Acquisition [Line Items]
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Current Assets, Receivables		$ 386,671
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Inventory		588,741
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Current Assets, Prepaid Expense and Other Assets		421,973
Property, plant, and equipment		472,623
Intangible assets		1,309,900
Goodwill		2,176,941
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Noncurrent Assets		22,196
Total assets acquired		5,379,045
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Current Liabilities, Accounts Payable		144,516
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Current Liabilities, Other		717,621
Other noncurrent liabilities		593,058
Total liabilities assumed		1,455,195
Net assets acquired		$ 3,923,850
Extant [Member]
Business Acquisition [Line Items]
Property, plant, and equipment				$ 4,103
Intangible assets				105,000
Goodwill				407,046
Total assets acquired				569,474
Current assets, excluding cash acquired				53,325
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Current Liabilities				9,876
Other noncurrent liabilities				26,453
Total liabilities assumed				36,329
Net assets acquired				$ 533,145

ACQUISITIONS Pro Forma Table (D

ACQUISITIONS Pro Forma Table (Details) - Esterline [Member] - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Sep. 30, 2019	Sep. 30, 2018
Business Acquisition [Line Items]
Business Acquisition, Pro Forma Revenue	$ 5,860,561	$ 5,291,760
Business Acquisition, Pro Forma Income (Loss) from Continuing Operations, Net of Tax	$ 847,055	$ 551,211
Business Acquisition, Pro Forma Earnings Per Share, Basic	$ 13,080	$ 8,900

SUMMARY OF SIGNIFICANT ACCOUN_3

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Narratives (Detail) - USD ($) $ in Millions	6 Months Ended	12 Months Ended
	Mar. 31, 2018	Sep. 30, 2019	Sep. 30, 2017
Summary Of Significant Accounting Policies [Line Items]
Research and development expense	$ 73.8	$ 116.8	$ 73.8
Finite lived intangible asset useful life		18 years
Land Improvements | Minimum
Summary Of Significant Accounting Policies [Line Items]
Property, plant and equipment, useful life		10 years
Land Improvements | Maximum
Summary Of Significant Accounting Policies [Line Items]
Property, plant and equipment, useful life		20 years
Building and improvements | Minimum
Summary Of Significant Accounting Policies [Line Items]
Property, plant and equipment, useful life		5 years
Building and improvements | Maximum
Summary Of Significant Accounting Policies [Line Items]
Property, plant and equipment, useful life		30 years
Machinery and equipment | Minimum
Summary Of Significant Accounting Policies [Line Items]
Property, plant and equipment, useful life		2 years
Machinery and equipment | Maximum
Summary Of Significant Accounting Policies [Line Items]
Property, plant and equipment, useful life		10 years
Furniture and Fixtures | Minimum
Summary Of Significant Accounting Policies [Line Items]
Property, plant and equipment, useful life		3 years
Furniture and Fixtures | Maximum
Summary Of Significant Accounting Policies [Line Items]
Property, plant and equipment, useful life		10 years
Technology Intangible Assets | Minimum
Summary Of Significant Accounting Policies [Line Items]
Finite lived intangible asset useful life		20 years
Technology Intangible Assets | Maximum
Summary Of Significant Accounting Policies [Line Items]
Finite lived intangible asset useful life		22 years
Order backlog
Summary Of Significant Accounting Policies [Line Items]
Finite lived intangible asset useful life		1 year 6 months
Order backlog | Minimum
Summary Of Significant Accounting Policies [Line Items]
Finite lived intangible asset useful life		1 year
Other intangible assets | Minimum
Summary Of Significant Accounting Policies [Line Items]
Finite lived intangible asset useful life		20 years

RECENT ACCOUNTING PRONOUNCEME_2

RECENT ACCOUNTING PRONOUNCEMENTS - Narratives (Details) - USD ($) $ in Thousands	Sep. 30, 2019	Sep. 30, 2018
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Debt issue cost	$ 147,724	$ 101,170

REVENUE RECOGNITION (Details)

REVENUE RECOGNITION (Details) - USD ($) $ in Thousands		6 Months Ended	12 Months Ended
		Mar. 31, 2018	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2017	Oct. 01, 2018
Contract with Customer, Asset, Net, Current	[1]		$ 44,097			$ 18,328
Unbilled Receivables, Current	[2]			$ 10,056		18,328
NET SALES			5,223,203	3,811,126	$ 3,504,286
Inventories—Net			1,232,649	805,292		801,315
DEFERRED INCOME TAXES			440,817	399,496		400,507
Accumulated deficit			(3,119,956)	(2,246,578)		(2,243,294)
Contract with Customer, Asset, Current, Increase or Decrease	[1]		25,769
Contract with Customer, Asset, Net, Noncurrent	[3]		7,238			118
Contract with customer, Asset, Non-current, Increase or Decrease	[3]		7,120
Contract with Customer, Asset, after Allowance for Credit Loss			51,335			18,446
Contract assets, Increase or Decrease			32,889
Contract with Customer, Liability, Current	[4]		17,840			2,742
Contract liabilities, Current, Increase or Decrease	[4]		15,098
Contract with Customer, Liability, Noncurrent	[5]		13,234			0
Contract liabilities, Non-current, Increase or Decrease	[5]		13,234
Contract with Customer, Liability			31,074			2,742
Contract Liabilities, Increase or Decrease			28,332
Net Contract Asset			20,261			$ 15,704
Net Contract Asset, Increase or Decrease			4,557
Accounting Standards Update 2014-09 [Member]
Unbilled Receivables, Current	[2]			8,272
Cumulative Effect on Retained Earnings, Net of Tax			3,284
Inventories—Net				(3,977)
DEFERRED INCOME TAXES				1,011
Accumulated Deficit | Accounting Standards Update 2014-09 [Member]
Cumulative Effect on Retained Earnings, Net of Tax			$ 3,284
Accumulated deficit				$ 3,284
Revenue Benchmark [Member] | Customer 2
Percentage of net sales from one customer		10.00%	11.00%		11.00%
Revenue Benchmark [Member] | Customer 2 | Airframe
Percentage of net sales from one customer			60.00%
Revenue Benchmark [Member] | Customer 2 | Power & Control
Percentage of net sales from one customer			40.00%
Revenue Benchmark [Member] | Customer 1
Percentage of net sales from one customer		11.00%			13.00%
Geographic Distribution, Foreign
NET SALES		$ 1,355,100	$ 1,778,400		$ 1,318,900
[1]	Included in prepaid expenses and other on the consolidated balance sheet.
[2]	Included in prepaid expenses and other on the consolidated balance sheet.
[3]	Included in other non-current assets on the consolidated balance sheet.
[4]	Included in accrued liabilities on the consolidated balance sheet.
[5]	Included in other non-current liabilities on the consolidated balance sheet.

EARNINGS PER SHARE - Computatio

EARNINGS PER SHARE - Computation of Basic and Diluted Earnings Per Share (Detail) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	12 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2017
Earnings Per Share [Abstract]
INCOME FROM CONTINUING OPERATIONS INCLUDING NONCONTROLLING INTERESTS	$ 840,879	$ 961,536	$ 628,541
NET INCOME ATTRIBUTABLE TO NONCONTROLLING INTERESTS	(1,541)	0	0
Net income from continuing operations attributable to TD Group	839,338	961,536	628,541
Numerator for earnings per share:
Less dividends paid on participating securities	(111,021)	(56,148)	(159,257)
Net Income Attributable to Continuing Operations Available To Common Stockholders Basic And Vested Options Deemed Participating Securities	728,317	905,388	469,284
INCOME (LOSS) FROM DISCONTINUED OPERATIONS, NET OF TAX	50,432	(4,474)	(31,654)
Net income applicable to common stock-basic and diluted	$ 778,749	$ 900,914	$ 437,630
Denominator for basic and diluted earnings per share under the two-class method:
Weighted average common shares outstanding	53,091	52,345	52,517
Vested options deemed participating securities	3,174	3,252	3,013
Total shares for basic and diluted earnings per share (shares)	56,265	55,597	55,530
Net earnings per share from continuing operations—basic and diluted	$ 12.94	$ 16.28	$ 8.45
Net earnings (loss) per share from discontinued operations—basic and diluted	0.90	(0.08)	(0.57)
Net earnings per share	$ 13.84	$ 16.20	$ 7.88

TRADE ACCOUNTS RECEIVABLE - Nar

TRADE ACCOUNTS RECEIVABLE - Narratives (Detail) - Accounts Receivable	12 Months Ended
	Sep. 30, 2019
Trade Accounts Receivable Securitization and Sale Program [Line Items]
Percentage of net sales from one customer	20.00%
Customer 1
Trade Accounts Receivable Securitization and Sale Program [Line Items]
Percentage of net sales from one customer	13.00%
Customer 2
Trade Accounts Receivable Securitization and Sale Program [Line Items]
Percentage of net sales from one customer	7.00%
Geographic Distribution, Foreign
Trade Accounts Receivable Securitization and Sale Program [Line Items]
Percentage of net sales from one customer	36.00%

TRADE ACCOUNTS RECEIVABLE - Con

TRADE ACCOUNTS RECEIVABLE - Content Trade Accounts Receivable (Detail) - USD ($) $ in Thousands	Sep. 30, 2019	Sep. 30, 2018
Receivables [Abstract]
Trade accounts receivable—gross	$ 1,085,005	$ 708,984
Allowance for uncollectible accounts	(17,402)	(4,674)
Trade accounts receivable—net	$ 1,067,603	$ 704,310

INVENTORIES - Schedule of Inven

INVENTORIES - Schedule of Inventories (Detail) - USD ($) $ in Thousands	Sep. 30, 2019	Oct. 01, 2018	Sep. 30, 2018
Inventory Disclosure [Abstract]
Raw materials and purchased component parts	$ 804,687		$ 540,290
Work-in-progress	360,230		237,335
Finished goods	191,535		127,018
Total	1,356,452		904,643
Reserves for excess and obsolete inventory	(123,803)		(99,351)
Inventories—Net	$ 1,232,649	$ 801,315	$ 805,292

PROPERTY, PLANT AND EQUIPMENT -

PROPERTY, PLANT AND EQUIPMENT - Schedule of Property, Plant and Equipment (Detail) - USD ($) $ in Thousands	Sep. 30, 2019	Sep. 30, 2018
Property, Plant and Equipment [Abstract]
Land and improvements	$ 95,536	$ 77,455
Buildings and improvements	407,461	171,269
Machinery, equipment and other	628,096	448,014
Construction in progress	52,241	31,237
Total	1,183,334	727,975
Accumulated depreciation	(426,577)	(339,642)
Property, plant and equipment-net	$ 756,757	$ 388,333

INTANGIBLE ASSETS - Schedule of

INTANGIBLE ASSETS - Schedule of Intangible Assets (Detail) - USD ($) $ in Thousands	Sep. 30, 2019	Sep. 30, 2018
Acquired Finite-Lived Intangible Assets [Line Items]
Intangible Assets, Gross (Excluding Goodwill)	$ 3,323,661	$ 2,232,697
Intangible Assets, Accumulated Amortization	579,841	444,293
OTHER INTANGIBLE ASSETS—NET	2,743,820	1,788,404
Technology
Acquired Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	1,805,715	1,347,314
Accumulated Amortization	496,311	416,579
Net	1,309,404	930,735
Order backlog
Acquired Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	106,889	12,200
Accumulated Amortization	44,603	5,409
Net	62,286	6,791
Customer-Related Intangible Assets [Member]
Acquired Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	437,973	62,561
Accumulated Amortization	29,777	14,277
Net	408,196	48,284
Other intangible assets
Acquired Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	16,707	10,873
Accumulated Amortization	9,150	8,028
Net	7,557	2,845
Trademarks and trade names
Acquired Finite-Lived Intangible Assets [Line Items]
Indefinite-Lived Intangible Assets (Excluding Goodwill), Gross	956,377	799,749
Indefinite-Lived Intangible Assets, Accumulated Amortization	0	0
Intangible Assets (Excluding Goodwill), Net	$ 956,377	$ 799,749

INTANGIBLE ASSETS - Schedule _2

INTANGIBLE ASSETS - Schedule of Aggregate Amortization Expense (Detail) - USD ($) $ in Thousands	12 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2017
Goodwill and Intangible Assets Disclosure [Abstract]
Amortization of intangible assets	$ 134,952	$ 72,454	$ 89,226

INTANGIBLE ASSETS - Schedule _3

INTANGIBLE ASSETS - Schedule of Finite-Lived Assets, Future Amortization (Details) $ in Thousands	Sep. 30, 2019USD ($)
Goodwill and Intangible Assets Disclosure [Abstract]
Finite-Lived Intangible Assets, Amortization Expense, Next Twelve Months	$ 182,583
Finite-Lived Intangible Assets, Amortization Expense, Year Two	119,067
Finite-Lived Intangible Assets, Amortization Expense, Year Three	119,067
Finite-Lived Intangible Assets, Amortization Expense, Year Four	119,067
Finite-Lived Intangible Assets, Amortization Expense, Year Five	$ 119,067

INTANGIBLE ASSETS - Schedule _4

INTANGIBLE ASSETS - Schedule of Intangible Assets Acquired (Detail) - USD ($) $ in Thousands	6 Months Ended	12 Months Ended
	Mar. 31, 2018	Sep. 30, 2019
Acquired Finite-Lived Intangible Assets [Line Items]
Goodwill	$ 475,861	$ 2,194,324
Intangible assets not subject to amortization		2,432,524
Intangible assets subject to amortization		1,086,535
Total - Intangible assets both subject to and not subject to amortization		$ 3,519,059
Amortization Period (in years)		18 years
Goodwill
Acquired Finite-Lived Intangible Assets [Line Items]
Goodwill		$ 2,194,324
Trademarks and trade names
Acquired Finite-Lived Intangible Assets [Line Items]
Intangible assets not subject to amortization		238,200
Technology
Acquired Finite-Lived Intangible Assets [Line Items]
Intangible assets subject to amortization		$ 503,500
Amortization Period (in years)		20 years
Order backlog
Acquired Finite-Lived Intangible Assets [Line Items]
Intangible assets subject to amortization		$ 99,100
Amortization Period (in years)		1 year 6 months
Customer-Related Intangible Assets [Member]
Acquired Finite-Lived Intangible Assets [Line Items]
Intangible assets subject to amortization		$ 483,935
Amortization Period (in years)		20 years

INTANGIBLE ASSETS - Summary of

INTANGIBLE ASSETS - Summary of Changes in Carrying Value of Goodwill (Detail) - USD ($) $ in Thousands	6 Months Ended	12 Months Ended
	Mar. 31, 2018	Sep. 30, 2019
Goodwill [Line Items]
Goodwill, Beginning Balance	$ 5,745,338	$ 6,223,290
Goodwill acquired during the year	475,861	2,194,324
Purchase price allocation adjustments	5,354	(31,591)
Goodwill, Foreign Currency Translation Gain (Loss)	(3,258)	(42,930)
Other	(5)
Goodwill, Ending Balance		7,820,103
Power & Control
Goodwill [Line Items]
Goodwill, Beginning Balance	3,269,981	3,677,683
Goodwill acquired during the year	402,540	468,613
Purchase price allocation adjustments	5,354	(8,690)
Goodwill, Foreign Currency Translation Gain (Loss)	0	(16,422)
Other	(192)
Goodwill, Ending Balance		4,121,184
Airframe
Goodwill [Line Items]
Goodwill, Beginning Balance	2,382,082	2,452,332
Goodwill acquired during the year	73,321	1,179,999
Purchase price allocation adjustments	0	(22,901)
Goodwill, Foreign Currency Translation Gain (Loss)	(3,258)	(11,695)
Other	187
Goodwill, Ending Balance		3,597,735
Non-aviation
Goodwill [Line Items]
Goodwill, Beginning Balance	93,275	93,275
Goodwill acquired during the year	0	545,712
Purchase price allocation adjustments	0	0
Goodwill, Foreign Currency Translation Gain (Loss)	0	(14,813)
Other	$ 0
Goodwill, Ending Balance		$ 101,184

ACCRUED LIABILITIES - Schedule

ACCRUED LIABILITIES - Schedule of Accrued Liabilities (Detail) - USD ($) $ in Thousands	Sep. 30, 2019	Sep. 30, 2018
Payables and Accruals [Abstract]
Compensation and related benefits	$ 177,862	$ 81,035
Interest	92,642	96,590
Interest rate swap agreements	13,219	528
Product warranties	33,882	21,056
Dividend Equivalent Payments On Certain Stock Options, Current	63,796	24,200
Environmental and other litigation reserves	12,016	31,079
Taxes Payable	44,370	9,168
Loss Contingency, Accrual, Current	64,665	11,682
Other	173,243	76,105
Total	$ 675,695	$ 351,443

DEBT - Narratives (Detail)

DEBT - Narratives (Detail) - USD ($) $ in Thousands	Oct. 29, 2019	Feb. 01, 2019	Jan. 30, 2019	Mar. 31, 2018	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2014	Mar. 15, 2019	Mar. 14, 2019	May 08, 2018	Mar. 01, 2017
Debt Instrument [Line Items]
Debt instrument, face amount					$ 16,712,607
Refinancing costs					$ 3,013	$ 6,396	$ 39,807
Debt Instrument, Interest Rate, Effective Percentage					2.94%
Percentage of ownership in subsidiary					100.00%
Long-term Debt, Gross					$ 16,712,607	12,699,932
Asset-backed Securities
Debt Instrument [Line Items]
Debt Instrument, Term								1 year
Short-term Bank Loans and Notes Payable, Gross					$ 350,000	300,000
Asset-backed Securities, Securitized Loans and Receivables [Member]
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Stated Percentage					0.90%
Asset-backed Securities, Securitized Loans and Receivables [Member] | Asset-backed Securities
Debt Instrument [Line Items]
Short-term Bank Loans and Notes Payable, Gross					$ 350,000
Revolving Credit Facility [Member]
Debt Instrument [Line Items]
Maximum borrowing capacity					760,000	$ 600,000
Debt Instrument, Increase in Face Amount										$ 160,000
Letters of Credit Outstanding, Amount					41,500
Line of Credit Facility, Remaining Borrowing Capacity					718,500
Multi-currency Revolving Commitment [Member]
Debt Instrument [Line Items]
Maximum borrowing capacity					151,500
Debt Instrument, Increase in Face Amount										$ 52,100
Secured Debt [Member] | Senior Secured Notes $200M Due 2026 6.25% [Member]
Debt Instrument [Line Items]
Debt Instrument, Redemption Price, Percentage		101.00%
Debt Instrument, Interest Rate, Stated Percentage		6.25%
Debt Instrument, Unamortized Premium					2,000
Long-term Debt, Gross		$ 200,000
Secured Debt [Member] | Senior Secured Notes $3.8B Due 2026 6.25% [Member]
Debt Instrument [Line Items]
Debt Instrument, Redemption Price, Percentage			100.00%
Debt Instrument, Interest Rate, Stated Percentage			6.25%
Long-term Debt, Gross			$ 3,800,000
Secured Debt [Member] | Senior Secured Notes $4B Due 2026 6.25% [Member]
Debt Instrument [Line Items]
Debt Issuance Costs, Gross					65,600
Refinancing costs					$ 800
Long-term Debt, Gross		$ 4,000,000
Term Loans
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Effective Percentage					4.83%	4.58%
Long-term Debt, Gross					$ 7,523,507	$ 7,599,932
Term Loans | Tranche G [Member]
Debt Instrument [Line Items]
Basis spread on LIBOR				0.00%	2.50%
Long-term Debt, Gross					$ 1,778,200	1,796,300
Term Loans | Tranche C
Debt Instrument [Line Items]
Basis spread on LIBOR				3.00%	0.00%
Term Loans | Tranche D
Debt Instrument [Line Items]
Basis spread on LIBOR				3.00%	2.50%
Term Loans | Tranche E
Debt Instrument [Line Items]
Basis spread on LIBOR				3.00%	2.50%
Long-term Debt, Gross					$ 2,221,200	2,243,700
Term Loans | Tranche F
Debt Instrument [Line Items]
Basis spread on LIBOR				3.00%	2.50%
Long-term Debt, Gross					$ 3,524,100	$ 3,559,900
Senior Subordinated Notes | 5.50% Senior Subordinated Notes, Due 2020
Debt Instrument [Line Items]
Write-off of debt issuance costs					$ 1,700
Debt Instrument, Interest Rate, Stated Percentage					5.50%	5.50%
Debt Instrument, Repurchased Face Amount									$ 550,000
Debt Instrument, Repurchase Amount									$ 12,600
Long-term Debt, Gross						$ 550,000
Senior Subordinated Notes | 7.50% Senior Subordinated Notes, Due 2021
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Stated Percentage					0.00%	7.50%
Senior Subordinated Notes | 6.00% Senior Subordinated Notes, Due 2022
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Stated Percentage					6.00%	6.00%
Long-term Debt, Gross					$ 1,150,000	$ 1,150,000
Senior Subordinated Notes | 6.50% Senior Subordinated Notes, Due 2024
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Stated Percentage					6.50%	6.50%
Long-term Debt, Gross					$ 1,200,000	$ 1,200,000
Senior Subordinated Notes | 6.50% Senior Subordinated Notes, Due 2025
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Stated Percentage					6.50%	6.50%
Long-term Debt, Gross					$ 750,000	$ 750,000						$ 300,000
Senior Subordinated Notes | 6.375% Senior Subordinated Notes, Due 2026
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Stated Percentage					6.375%	6.375%
Long-term Debt, Gross					$ 950,000	$ 950,000
Senior Subordinated Notes | Senior subordinated notes due 2026 6.875%
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Stated Percentage					6.875%	0.00%
Long-term Debt, Gross					$ 500,000	$ 500,000					$ 500,000
Senior Subordinated Notes | Senior Subordinated Notes $550M Due 2027 7.50% [Member]
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Stated Percentage		7.50%
Debt Instrument, Unamortized Premium					5,800
Long-term Debt, Gross		$ 550,000			$ 550,000
Subsequent Event [Member] | Senior Subordinated Notes | 6.00% Senior Subordinated Notes, Due 2022
Debt Instrument [Line Items]
Subordinated Notes Redemption, Amount	$ 1,150,000
Subsequent Event [Member] | Senior Subordinated Notes | Senior Subordinated Notes $2650M Due 2027 5.50% [Member]
Debt Instrument [Line Items]
Debt Instrument, Redemption Price, Percentage	100.00%
Debt Instrument, Interest Rate, Stated Percentage	5.50%
Long-term Debt, Gross	$ 2,650,000

DEBT - Schedule of Debt (Detail

DEBT - Schedule of Debt (Detail) - USD ($) $ in Thousands	Sep. 30, 2019	Feb. 01, 2019	Sep. 30, 2018	May 08, 2018	Mar. 01, 2017
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Effective Percentage	2.94%
Debt Issuance Costs, Net	$ (147,724)		$ (101,170)
Debt Instrument, Unamortized Discount (Premium), Net	15,449		20,999
Short-term borrowings - trade receivable securitization facility	349,519		299,519
Long-term Debt, Gross	16,712,607		12,699,932
Total debt outstanding	16,549,434		12,577,763
Less current portion	80,213		75,817
Long-term Debt, Excluding Current Maturities, Gross	16,631,656		12,623,505
Deferred Finance Costs, Excluding Current Maturities	(146,986)		(100,560)
Debt Instrument, Unamortized Discount, Excluding Current Maturities	(15,449)		(20,999)
Long-term debt	$ 16,469,221		$ 12,501,946
Term Loans
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Effective Percentage	4.83%		4.58%
Debt Issuance Costs, Net	$ (57,744)		$ (69,697)
Debt Instrument, Unamortized Discount (Premium), Net	17,214		21,030
Long-term Debt, Gross	7,523,507		7,599,932
Total debt outstanding	7,448,549		7,509,205
Government Refundable Advances [Member]
Debt Instrument [Line Items]
Debt Issuance Costs, Net	0
Debt Instrument, Unamortized Discount (Premium), Net	0
Total debt outstanding	39,195		0
Government refundable advances	39,195
Capital Lease Obligations [Member]
Debt Instrument [Line Items]
Debt Issuance Costs, Net	0
Debt Instrument, Unamortized Discount (Premium), Net	0
Total debt outstanding	49,906		0
Capital Lease Obligations	49,905
Long-term Debt, Current Maturities
Debt Instrument [Line Items]
Debt Issuance Costs, Net	(738)		(610)
Debt Instrument, Unamortized Discount (Premium), Net	0		0
Long-term Debt, Current Maturities, Gross	80,951		76,427
Less current portion	80,213		75,817
Asset-backed Securities
Debt Instrument [Line Items]
Short-term Bank Loans and Notes Payable, Gross	350,000		300,000
Debt Issuance Costs, Net	(481)		(481)
Debt Instrument, Unamortized Discount (Premium), Net	0		0
Short-term borrowings - trade receivable securitization facility	$ 349,519		299,519
Asset-backed Securities, Securitized Loans and Receivables [Member]
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Stated Percentage	0.90%
Asset-backed Securities, Securitized Loans and Receivables [Member] | Asset-backed Securities
Debt Instrument [Line Items]
Short-term Bank Loans and Notes Payable, Gross	$ 350,000
5.50% Senior Subordinated Notes, Due 2020 | Senior Subordinated Notes
Debt Instrument [Line Items]
Debt Issuance Costs, Net			(2,187)
Debt Instrument, Unamortized Discount (Premium), Net			0
Long-term Debt, Gross			$ 550,000
Debt Instrument, Interest Rate, Stated Percentage	5.50%		5.50%
Total debt outstanding	$ 0		$ 547,813
7.50% Senior Subordinated Notes, Due 2021 | Senior Subordinated Notes
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Stated Percentage	0.00%		7.50%
6.00% Senior Subordinated Notes, Due 2022 | Senior Subordinated Notes
Debt Instrument [Line Items]
Debt Issuance Costs, Net	$ (4,061)		$ (5,501)
Debt Instrument, Unamortized Discount (Premium), Net	0		0
Long-term Debt, Gross	$ 1,150,000		$ 1,150,000
Debt Instrument, Interest Rate, Stated Percentage	6.00%		6.00%
Total debt outstanding	$ 1,145,939		$ 1,144,499
6.50% Senior Subordinated Notes, Due 2024 | Senior Subordinated Notes
Debt Instrument [Line Items]
Debt Issuance Costs, Net	(5,690)		(6,866)
Debt Instrument, Unamortized Discount (Premium), Net	0		0
Long-term Debt, Gross	$ 1,200,000		$ 1,200,000
Debt Instrument, Interest Rate, Stated Percentage	6.50%		6.50%
Total debt outstanding	$ 1,194,310		$ 1,193,134
6.50% Senior Subordinated Notes, Due 2025 | Senior Subordinated Notes
Debt Instrument [Line Items]
Debt Issuance Costs, Net	(2,977)		(3,505)
Debt Instrument, Unamortized Discount (Premium), Net	(3,090)		(3,636)
Long-term Debt, Gross	$ 750,000		$ 750,000		$ 300,000
Debt Instrument, Interest Rate, Stated Percentage	6.50%		6.50%
Total debt outstanding	$ 750,113		$ 750,131
6.375% Senior Subordinated Notes, Due 2026 | Senior Subordinated Notes
Debt Instrument [Line Items]
Debt Issuance Costs, Net	(6,790)		(7,798)
Debt Instrument, Unamortized Discount (Premium), Net	0		0
Long-term Debt, Gross	$ 950,000		$ 950,000
Debt Instrument, Interest Rate, Stated Percentage	6.375%		6.375%
Total debt outstanding	$ 943,210		$ 942,202
Senior subordinated notes due 2026 6.875% | Senior Subordinated Notes
Debt Instrument [Line Items]
Debt Issuance Costs, Net	(5,532)		(5,616)
Debt Instrument, Unamortized Discount (Premium), Net	3,137		3,605
Long-term Debt, Gross	$ 500,000		$ 500,000	$ 500,000
Debt Instrument, Interest Rate, Stated Percentage	6.875%		0.00%
Total debt outstanding	$ 491,331		$ 490,779
Senior Secured Notes $4B Due 2026 6.25% [Member] | Senior Notes [Member]
Debt Instrument [Line Items]
Debt Issuance Costs, Net	(59,630)
Debt Instrument, Unamortized Discount (Premium), Net	(1,812)
Long-term Debt, Gross	4,000,000
Total debt outstanding	3,942,182
Senior Subordinated Notes $550M Due 2027 7.50% [Member] | Senior Subordinated Notes
Debt Instrument [Line Items]
Debt Issuance Costs, Net	(5,300)
Debt Instrument, Unamortized Discount (Premium), Net	0
Long-term Debt, Gross	550,000	$ 550,000
Debt Instrument, Interest Rate, Stated Percentage		7.50%
Total debt outstanding	$ 544,700		$ 0

DEBT - Schedule of Term Loans (

DEBT - Schedule of Term Loans (Details) - USD ($) $ in Thousands	6 Months Ended	12 Months Ended
	Mar. 31, 2018	Sep. 30, 2019	Sep. 30, 2018	Mar. 01, 2017
Debt Instrument [Line Items]
Long-term Debt, Gross		$ 16,712,607	$ 12,699,932
Term Loans
Debt Instrument [Line Items]
Long-term Debt, Gross		$ 7,523,507	7,599,932
Term Loans | Tranche C
Debt Instrument [Line Items]
Basis spread on LIBOR	3.00%	0.00%
Term Loans | Tranche D
Debt Instrument [Line Items]
Basis spread on LIBOR	3.00%	2.50%
Term Loans | Tranche E
Debt Instrument [Line Items]
Basis spread on LIBOR	3.00%	2.50%
Long-term Debt, Gross		$ 2,221,200	2,243,700
Term Loans | Tranche F
Debt Instrument [Line Items]
Basis spread on LIBOR	3.00%	2.50%
Long-term Debt, Gross		$ 3,524,100	3,559,900
Term Loans | Tranche G [Member]
Debt Instrument [Line Items]
Basis spread on LIBOR	0.00%	2.50%
Long-term Debt, Gross		$ 1,778,200	1,796,300
Senior Subordinated Notes | 5.50% Senior Subordinated Notes, Due 2020
Debt Instrument [Line Items]
Long-term Debt, Gross			$ 550,000
Debt Instrument, Interest Rate, Stated Percentage		5.50%	5.50%
Senior Subordinated Notes | 7.50% Senior Subordinated Notes, Due 2021
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Stated Percentage		0.00%	7.50%
Senior Subordinated Notes | 6.00% Senior Subordinated Notes, Due 2022
Debt Instrument [Line Items]
Long-term Debt, Gross		$ 1,150,000	$ 1,150,000
Debt Instrument, Interest Rate, Stated Percentage		6.00%	6.00%
Senior Subordinated Notes | 6.50% Senior Subordinated Notes, Due 2024
Debt Instrument [Line Items]
Long-term Debt, Gross		$ 1,200,000	$ 1,200,000
Debt Instrument, Interest Rate, Stated Percentage		6.50%	6.50%
Senior Subordinated Notes | 6.50% Senior Subordinated Notes, Due 2025
Debt Instrument [Line Items]
Long-term Debt, Gross		$ 750,000	$ 750,000	$ 300,000
Debt Instrument, Interest Rate, Stated Percentage		6.50%	6.50%
Senior Subordinated Notes | 6.375% Senior Subordinated Notes, Due 2026
Debt Instrument [Line Items]
Long-term Debt, Gross		$ 950,000	$ 950,000
Debt Instrument, Interest Rate, Stated Percentage		6.375%	6.375%

DEBT - Future Maturities of Lon

DEBT - Future Maturities of Long-Term Debt (Detail) $ in Thousands	Sep. 30, 2019USD ($)
Debt Disclosure [Abstract]
Long-term Debt, Maturities, Repayments of Principal in Next Twelve Months	$ 80,951
Long-term Debt, Maturities, Repayments of Principal in Year Two	81,979
Long-term Debt, Maturities, Repayments of Principal in Year Three	1,232,200
Long-term Debt, Maturities, Repayments of Principal in Year Four	3,462,528
Long-term Debt, Maturities, Repayments of Principal in Year Five	2,933,675
Long-term Debt, Maturities, Repayments of Principal after Year Five	8,921,274
Debt Instrument, Face Amount	$ 16,712,607

DEBT -Schedule of Subordinated

DEBT -Schedule of Subordinated Borrowings (Details) - USD ($) $ in Thousands	Sep. 30, 2019	Feb. 01, 2019	Sep. 30, 2018	May 08, 2018	Mar. 01, 2017
Subordinated Borrowing [Line Items]
Long-term Debt, Gross	$ 16,712,607		$ 12,699,932
Senior Subordinated Notes | 5.50% Senior Subordinated Notes, Due 2020
Subordinated Borrowing [Line Items]
Long-term Debt, Gross			$ 550,000
Debt Instrument, Interest Rate, Stated Percentage	5.50%		5.50%
Senior Subordinated Notes | 6.00% Senior Subordinated Notes, Due 2022
Subordinated Borrowing [Line Items]
Long-term Debt, Gross	$ 1,150,000		$ 1,150,000
Debt Instrument, Interest Rate, Stated Percentage	6.00%		6.00%
Senior Subordinated Notes | 6.50% Senior Subordinated Notes, Due 2024
Subordinated Borrowing [Line Items]
Long-term Debt, Gross	$ 1,200,000		$ 1,200,000
Debt Instrument, Interest Rate, Stated Percentage	6.50%		6.50%
Senior Subordinated Notes | 6.50% Senior Subordinated Notes, Due 2025
Subordinated Borrowing [Line Items]
Long-term Debt, Gross	$ 750,000		$ 750,000		$ 300,000
Debt Instrument, Interest Rate, Stated Percentage	6.50%		6.50%
Senior Subordinated Notes | 6.375% Senior Subordinated Notes, Due 2026
Subordinated Borrowing [Line Items]
Long-term Debt, Gross	$ 950,000		$ 950,000
Debt Instrument, Interest Rate, Stated Percentage	6.375%		6.375%
Senior Subordinated Notes | Senior subordinated notes due 2026 6.875%
Subordinated Borrowing [Line Items]
Long-term Debt, Gross	$ 500,000		$ 500,000	$ 500,000
Debt Instrument, Interest Rate, Stated Percentage	6.875%		0.00%
Senior Subordinated Notes | Senior Subordinated Notes $550M Due 2027 7.50% [Member]
Subordinated Borrowing [Line Items]
Long-term Debt, Gross	$ 550,000	$ 550,000
Debt Instrument, Interest Rate, Stated Percentage		7.50%

RETIREMENT PLANS - Narratives (

RETIREMENT PLANS - Narratives (Detail) - USD ($) $ in Thousands	12 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2017
Defined Benefit Plan Disclosure [Line Items]
Discount rate decrease by 25 basis points, change in pension obligation	$ 19,200
Discount rate increase by 25 basis points, change in pension obligation	20,300
Change in Net Periodic Benefit Cost, if 25 basis point decrease in discount rate	100
Increase in expected return on assets by 25 basis points, change in net periodic benefit cost	800
Decrease in expected return on assets by 25 basis points, change in net periodic benefit costs	800
Health Care Trend Rate, 100 basis point increase	1,500
Defined contribution plan, cost recognized	24,500	$ 14,900	$ 14,600
Defined benefit plan, accumulated benefit obligation	623,800	89,900
Defined Benefit Plan, Expected Amortization of Gain (Loss), Next Fiscal Year	1,500
Defined Benefit Plan, Expected Amortization of Prior Service Cost (Credit), Next Fiscal Year	200
Health Care Trend Rate, 100 basis point decrease	1,300
Qualified Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Contributions by Employer	1,400	1,600
Unqualified Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Contributions by Employer	900
UNITED STATES | Pension Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Amount	317,896	8,655	8,006
Defined benefit plan, accumulated benefit obligation	365,600
Defined Benefit Plan, Net Periodic Benefit Cost (Credit)	1,980	1,025	1,849
Defined Benefit Plan, Pension Plan with Projected Benefit Obligation in Excess of Plan Assets, Projected Benefit Obligation	378,800
Defined Benefit Plan, Funded (Unfunded) Status of Plan	(60,950)	(10,028)
Defined Benefit Plan, Plan Assets, Contributions by Employer	2,300	1,633
UNITED STATES | Supplemental Employee Retirement Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Funded (Unfunded) Status of Plan	22,100
UNITED STATES | Qualified Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Contributions by Employer	700
Foreign Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Contributions by Employer	5,300
Foreign Plan [Member] | Pension Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Amount	233,608	59,800	61,884
Defined benefit plan, accumulated benefit obligation	258,200
Defined Benefit Plan, Net Periodic Benefit Cost (Credit)	2,330	568	$ 1,127
Defined Benefit Plan, Pension Plan with Projected Benefit Obligation in Excess of Plan Assets, Projected Benefit Obligation	270,000
Defined Benefit Plan, Funded (Unfunded) Status of Plan	(36,401)	(12,740)
Defined Benefit Plan, Plan Assets, Contributions by Employer	$ 2,726	$ 1,049

RETIREMENT PLANS Tables (Detail

RETIREMENT PLANS Tables (Details) - USD ($) $ in Thousands	6 Months Ended	12 Months Ended
	Mar. 31, 2018	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2017
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Actual Allocation, Percentage		100.00%	100.00%
Defined Benefit Plan, Expected Future Benefit Payment, Next Twelve Months		$ 34,275
Defined Benefit Plan, Expected Future Benefit Payment, Year Two		34,700
Defined Benefit Plan, Expected Future Benefit Payment, Year Three		35,697
Defined Benefit Plan, Expected Future Benefit Payment, Year Four		37,305
Defined Benefit Plan, Expected Future Benefit Payment, Year Five		38,059
Defined Benefit Plan, Expected Future Benefit Payment, Five Fiscal Years Thereafter		201,998
Fair Value, Inputs, Level 1 [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Amount		80,963	$ 8,799
Fair Value, Inputs, Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Amount		$ 86,281	$ 0
Equity Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Actual Allocation, Percentage		35.10%	27.10%
Defined Benefit Plan, Equity Securities, US [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Amount		$ 3,472	$ 3,545
Defined Benefit Plan, Equity Securities, US [Member] | Fair Value, Inputs, Level 1 [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Amount		3,472	3,545
Defined Benefit Plan, Equity Securities, US [Member] | Fair Value, Inputs, Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Amount		0	0
Defined Benefit Plan, Equity Securities, Non-US [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Amount		47,903	4,959
Defined Benefit Plan, Equity Securities, Non-US [Member] | Fair Value, Inputs, Level 1 [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Amount		47,903	4,959
Defined Benefit Plan, Equity Securities, Non-US [Member] | Fair Value, Inputs, Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Amount		0	0
Defined Benefit Plan, Equity Securities, Non-US [Member] | Fair Value Measured at Net Asset Value Per Share [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Amount		142,132	10,056
US Treasury and Government [Member] | Fair Value Measured at Net Asset Value Per Share [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Amount		86,214
Defined Benefit Plan, Cash and Cash Equivalents [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Amount		29,588	295
Defined Benefit Plan, Cash and Cash Equivalents [Member] | Fair Value, Inputs, Level 1 [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Amount		29,588	295
Defined Benefit Plan, Cash and Cash Equivalents [Member] | Fair Value, Inputs, Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Amount		0	0
Debt Security, Corporate, US [Member] | Fair Value Measured at Net Asset Value Per Share [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Amount		108,135	3,710
Debt Security, Corporate, Non-US [Member] | Fair Value Measured at Net Asset Value Per Share [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Amount		17,449	16,759
Debt Security, Government, Non-US [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Amount		86,281
Debt Security, Government, Non-US [Member] | Fair Value, Inputs, Level 1 [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Amount		0
Debt Security, Government, Non-US [Member] | Fair Value, Inputs, Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Amount		86,281
Debt Security, Government, Non-US [Member] | Fair Value Measured at Net Asset Value Per Share [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Amount		$ 30,330	$ 29,131
Debt Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Actual Allocation, Percentage		59.50%	72.50%
Cash and Cash Equivalents [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Actual Allocation, Percentage		5.40%	0.40%
Foreign Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Contributions by Employer		$ 5,300
Other Postretirement Benefits Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Net Periodic Benefit Cost (Credit)	$ 400	$ 400		$ 400
Other Postretirement Benefits Plan [Member] | UNITED STATES
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Assumptions Used Calculating Benefit Obligation, Discount Rate		2.86%	3.99%
Defined Benefit Plan, Benefit Obligation		$ 1,284	$ 957	1,002
Defined Benefit Plan, Benefit Obligation, Foreign Currency Translation Gain (Loss)		0	0
Defined Benefit Plan, Service Cost		5	5	5
Defined Benefit Plan, Interest Cost		40	31	42
Defined Benefit Plan, Benefit Obligation, Contributions by Plan Participant		0	0
Defined Benefit Plan, Benefit Obligation, Actuarial Gain (Loss)		176	(136)
Defined Benefit Plan, Benefit Obligation, Business Combination		196	0
Defined Benefit Plan, Benefit Obligation, Increase (Decrease) for Other Change		0	111
Defined Benefit Plan, Benefit Obligation, Benefits Paid		(90)	(56)
Defined Benefit Plan, Plan Assets, Amount		0	0	0
Defined Benefit Plan, Benefit Obligations		(1,284)	(957)
Defined Benefit Plan, Plan Assets, Foreign Currency Translation Gain (Loss)		0	0
Defined Benefit Plan, Plan Assets, Increase (Decrease) for Actual Return (Loss)		0	0
Defined Benefit Plan, Plan Assets, Contributions by Plan Participant		0	0
Defined Benefit Plan, Plan Assets, Contributions by Employer		90	56
Defined Benefit Plan, Plan Assets, Business Combination		0	0
Defined benefit plan, Plan assets, Other change		0	0
Defined Benefit Plan, Plan Assets, Administration Expense		0	0
Defined Benefit Plan, Plan Assets, Benefits Paid		(90)	(56)
Defined Benefit Plan, Funded (Unfunded) Status of Plan		(1,284)	(957)
Assets for Plan Benefits, Defined Benefit Plan		0	0
Liability, Defined Benefit Plan, Current		(154)	(88)
Liability, Defined Benefit Plan, Noncurrent		(1,130)	(869)
Liability, Defined Benefit Plan		(1,284)	(957)
Defined Benefit Plan, Accumulated Other Comprehensive Income (Loss), Gain (Loss), before Tax		(388)	(617)
Defined Benefit Plan, Accumulated Other Comprehensive (Income) Loss, Prior Service Cost (Credit), before Tax		192	216
Defined Benefit Plan, Accumulated Other Comprehensive (Income) Loss, before Tax		(196)	(401)
Defined Benefit Plan, Expected Return (Loss) on Plan Assets		0	0	0
Defined Benefit Plan, Benefit Obligation, Payment for Settlement		0	0	0
Defined Benefit Plan, Amortization of Prior Service Cost (Credit)		24	12	0
Defined Benefit Plan, Amortization of Gain (Loss)		(53)	(42)	(117)
Defined Benefit Plan, Net Periodic Benefit Cost (Credit)		$ 16	$ 6	(70)
Defined Benefit Plan, Health Care Cost Trend Rate Assumed, Next Fiscal Year		7.46%	8.50%
Defined Benefit Plan, Ultimate Health Care Cost Trend Rate		6.00%	6.00%
Other Postretirement Benefits Plan [Member] | Foreign Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Assumptions Used Calculating Benefit Obligation, Discount Rate		2.68%
Defined Benefit Plan, Benefit Obligation		$ 13,775	$ 0	0
Defined Benefit Plan, Benefit Obligation, Foreign Currency Translation Gain (Loss)		138	0
Defined Benefit Plan, Service Cost		208	0	0
Defined Benefit Plan, Interest Cost		227	0	0
Defined Benefit Plan, Benefit Obligation, Contributions by Plan Participant		0	0
Defined Benefit Plan, Benefit Obligation, Actuarial Gain (Loss)		1,058	0
Defined Benefit Plan, Benefit Obligation, Business Combination		12,459	0
Defined Benefit Plan, Benefit Obligation, Increase (Decrease) for Other Change		0	0
Defined Benefit Plan, Benefit Obligation, Benefits Paid		(315)	0
Defined Benefit Plan, Plan Assets, Amount		0	0	0
Defined Benefit Plan, Benefit Obligations		(13,775)	0
Defined Benefit Plan, Plan Assets, Foreign Currency Translation Gain (Loss)		0	0
Defined Benefit Plan, Plan Assets, Increase (Decrease) for Actual Return (Loss)		0	0
Defined Benefit Plan, Plan Assets, Contributions by Plan Participant		0	0
Defined Benefit Plan, Plan Assets, Contributions by Employer		315	0
Defined Benefit Plan, Plan Assets, Business Combination		0	0
Defined benefit plan, Plan assets, Other change		0	0
Defined Benefit Plan, Plan Assets, Administration Expense		0	0
Defined Benefit Plan, Plan Assets, Benefits Paid		(315)	0
Defined Benefit Plan, Funded (Unfunded) Status of Plan		(13,775)	0
Assets for Plan Benefits, Defined Benefit Plan		0	0
Liability, Defined Benefit Plan, Current		(714)	0
Liability, Defined Benefit Plan, Noncurrent		(13,061)	0
Liability, Defined Benefit Plan		(13,775)	0
Defined Benefit Plan, Accumulated Other Comprehensive Income (Loss), Gain (Loss), before Tax		1,060	0
Defined Benefit Plan, Accumulated Other Comprehensive (Income) Loss, Prior Service Cost (Credit), before Tax		0	0
Defined Benefit Plan, Accumulated Other Comprehensive (Income) Loss, before Tax		1,060	0
Defined Benefit Plan, Expected Return (Loss) on Plan Assets		0	0	0
Defined Benefit Plan, Benefit Obligation, Payment for Settlement		0	0	0
Defined Benefit Plan, Amortization of Prior Service Cost (Credit)		0	0	0
Defined Benefit Plan, Amortization of Gain (Loss)		0	0	0
Defined Benefit Plan, Net Periodic Benefit Cost (Credit)		$ 435	$ 0	0
Defined Benefit Plan, Health Care Cost Trend Rate Assumed, Next Fiscal Year		5.60%
Defined Benefit Plan, Ultimate Health Care Cost Trend Rate		4.10%
Pension Plan [Member] | UNITED STATES
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Assumptions Used Calculating Benefit Obligation, Discount Rate		3.03%	3.96%
Defined Benefit Plan, Benefit Obligation		$ 378,846	$ 18,683	19,966
Defined Benefit Plan, Benefit Obligation, Foreign Currency Translation Gain (Loss)		0	0
Defined Benefit Plan, Service Cost		4,486	277
Service Cost, Defined Benefit Plan			293	304
Defined Benefit Plan, Interest Cost		7,434	666
Interest Cost, Defined Benefit Plan			778	1,064
Defined Benefit Plan, Benefit Obligation, Contributions by Plan Participant		0	0
Defined Benefit Plan, Benefit Obligation, Actuarial Gain (Loss)		43,368	(660)
Defined Benefit Plan, Benefit Obligation, Business Combination		318,161	0
Defined Benefit Plan, Benefit Obligation, Increase (Decrease) for Other Change		440	0
Defined Benefit Plan, Benefit Obligation, Benefits Paid		(13,726)	(1,566)
Defined Benefit Plan, Plan Assets, Amount		317,896	8,655	8,006
Defined Benefit Plan, Benefit Obligations		(378,846)	(18,683)
Defined Benefit Plan, Plan Assets, Foreign Currency Translation Gain (Loss)		0	0
Defined Benefit Plan, Plan Assets, Increase (Decrease) for Actual Return (Loss)		30,743	582
Defined Benefit Plan, Plan Assets, Contributions by Plan Participant		0	0
Defined Benefit Plan, Plan Assets, Contributions by Employer		2,300	1,633
Defined Benefit Plan, Plan Assets, Business Combination		289,944	0
Defined benefit plan, Plan assets, Other change		0	0
Defined Benefit Plan, Plan Assets, Administration Expense		(20)	0
Defined Benefit Plan, Plan Assets, Benefits Paid		(13,726)	(1,566)
Defined Benefit Plan, Funded (Unfunded) Status of Plan		(60,950)	(10,028)
Assets for Plan Benefits, Defined Benefit Plan		0	0
Liability, Defined Benefit Plan, Current		(2,460)	(841)
Liability, Defined Benefit Plan, Noncurrent		(58,490)	(9,187)
Liability, Defined Benefit Plan		(60,950)	(10,028)
Defined Benefit Plan, Accumulated Other Comprehensive Income (Loss), Gain (Loss), before Tax		27,809	5,183
Defined Benefit Plan, Accumulated Other Comprehensive (Income) Loss, Prior Service Cost (Credit), before Tax		766	368
Defined Benefit Plan, Accumulated Other Comprehensive (Income) Loss, before Tax		28,575	5,551
Defined Benefit Plan, Expected Return (Loss) on Plan Assets		(10,339)	(517)	(463)
Defined Benefit Plan, Benefit Obligation, Payment for Settlement		0	0	0
Defined Benefit Plan, Amortization of Prior Service Cost (Credit)		62	36	0
Defined Benefit Plan, Amortization of Gain (Loss)		337	226	630
Defined Benefit Plan, Amortization of Transition Asset (Obligation)		0	209	314
Defined Benefit Plan, Net Periodic Benefit Cost (Credit)		$ 1,980	$ 1,025	1,849
Defined Benefit Plan, Assumptions Used Calculating Benefit Obligation, Rate of Compensation Increase		4.48%
Defined Benefit Plan, Assumptions Used Calculating Net Periodic Benefit Cost, Expected Long-term Rate of Return on Plan Assets		6.00%	6.50%
Pension Plan [Member] | Foreign Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Assumptions Used Calculating Benefit Obligation, Discount Rate		2.20%	2.68%
Defined Benefit Plan, Benefit Obligation		$ 270,009	$ 72,540	79,495
Defined Benefit Plan, Benefit Obligation, Foreign Currency Translation Gain (Loss)		(3,973)	(1,981)
Defined Benefit Plan, Service Cost		3,486	578
Service Cost, Defined Benefit Plan			545	760
Defined Benefit Plan, Interest Cost		4,806	1,821
Interest Cost, Defined Benefit Plan			1,798	1,721
Defined Benefit Plan, Benefit Obligation, Contributions by Plan Participant		380	60
Defined Benefit Plan, Benefit Obligation, Actuarial Gain (Loss)		28,127	(5,387)
Defined Benefit Plan, Benefit Obligation, Business Combination		171,377	0
Defined Benefit Plan, Benefit Obligation, Increase (Decrease) for Other Change		505	0
Defined Benefit Plan, Benefit Obligation, Benefits Paid		(7,239)	(2,046)
Defined Benefit Plan, Plan Assets, Amount		233,608	59,800	61,884
Defined Benefit Plan, Benefit Obligations		(270,009)	(72,540)
Defined Benefit Plan, Plan Assets, Foreign Currency Translation Gain (Loss)		(2,719)	(1,572)
Defined Benefit Plan, Plan Assets, Increase (Decrease) for Actual Return (Loss)		18,854	425
Defined Benefit Plan, Plan Assets, Contributions by Plan Participant		380	60
Defined Benefit Plan, Plan Assets, Contributions by Employer		2,726	1,049
Defined Benefit Plan, Plan Assets, Business Combination		162,015	0
Defined benefit plan, Plan assets, Other change		(209)	0
Defined Benefit Plan, Plan Assets, Administration Expense		0	0
Defined Benefit Plan, Plan Assets, Benefits Paid		(7,239)	(2,046)
Defined Benefit Plan, Funded (Unfunded) Status of Plan		(36,401)	(12,740)
Assets for Plan Benefits, Defined Benefit Plan		3,639	0
Liability, Defined Benefit Plan, Current		(482)	(254)
Liability, Defined Benefit Plan, Noncurrent		(39,558)	(12,486)
Liability, Defined Benefit Plan		(36,401)	(12,740)
Defined Benefit Plan, Accumulated Other Comprehensive Income (Loss), Gain (Loss), before Tax		23,533	9,416
Defined Benefit Plan, Accumulated Other Comprehensive (Income) Loss, Prior Service Cost (Credit), before Tax		875	185
Defined Benefit Plan, Accumulated Other Comprehensive (Income) Loss, before Tax		24,408	9,601
Defined Benefit Plan, Expected Return (Loss) on Plan Assets		(6,267)	(2,334)	(2,550)
Defined Benefit Plan, Benefit Obligation, Payment for Settlement		70	0	0
Defined Benefit Plan, Amortization of Prior Service Cost (Credit)		14	0	0
Defined Benefit Plan, Amortization of Gain (Loss)		221	559	1,196
Defined Benefit Plan, Amortization of Transition Asset (Obligation)		0	0	0
Defined Benefit Plan, Net Periodic Benefit Cost (Credit)		$ 2,330	$ 568	$ 1,127
Defined Benefit Plan, Assumptions Used Calculating Benefit Obligation, Rate of Compensation Increase		2.98%	3.22%
Defined Benefit Plan, Assumptions Used Calculating Net Periodic Benefit Cost, Expected Long-term Rate of Return on Plan Assets		4.16%	4.30%
Fair Value Measured at Net Asset Value Per Share [Member] | Fair Value Measured at Net Asset Value Per Share [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Amount		$ 551,504	$ 68,455
Fair Value, Inputs, Level 1, 2 and 3 [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Amount		$ 167,244	$ 8,799

INCOME TAXES - Narratives (Deta

INCOME TAXES - Narratives (Detail) - USD ($) $ in Millions	Jan. 01, 2018	Mar. 31, 2018	Mar. 31, 2018	Sep. 30, 2019	Sep. 30, 2017	Sep. 30, 2018
Income Tax Contingency [Line Items]
Statutory tax rate		35.00%	24.50%	21.00%	35.00%
State tax credit carryforward				$ 40.6
State tax credit carryforward expiration period				2025
Effect of unrecognized tax benefits on effective tax rate				$ 31.4		$ 14.1
Accrual for income tax penalties and interest				5		$ 1.9
U.S. Tax Cuts and Jobs Act Effective 2018 [Member]
Income Tax Contingency [Line Items]
Statutory tax rate	21.00%
Deferred Federal Income Tax Expense (Benefit)				176.4
Effective Income Tax Rate Reconciliation, Repatriation of Foreign Earnings, Amount				30
State
Income Tax Contingency [Line Items]
Net operating loss carryforward				$ 1,342.7
Minimum
Income Tax Contingency [Line Items]
Net tax loss carryforwards, expiration years				2019
Maximum
Income Tax Contingency [Line Items]
Net tax loss carryforwards, expiration years				2039
UNITED KINGDOM | Federal and United Kingdom
Income Tax Contingency [Line Items]
Net operating loss carryforward				$ 12.3
GERMANY | Federal and United Kingdom
Income Tax Contingency [Line Items]
Net operating loss carryforward				14.2
BELGIUM | Federal and United Kingdom
Income Tax Contingency [Line Items]
Net operating loss carryforward				39.5
FRANCE | Federal and United Kingdom
Income Tax Contingency [Line Items]
Net operating loss carryforward				$ 3.6

INCOME TAXES - Income Tax Provi

INCOME TAXES - Income Tax Provision on Income Before Income Taxes (Detail) - USD ($) $ in Thousands	12 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2017
Current
Federal	$ 153,704	$ 136,651	$ 179,884
State	14,911	11,771	8,596
Foreign	53,720	27,239	21,327
Total Current	222,335	175,661	209,807
Deferred	(349)	(151,640)	(918)
Income tax provision	$ 221,986	$ 24,021	$ 208,889

INCOME TAXES - Income Tax Expen

INCOME TAXES - Income Tax Expense Reconciliation (Detail) - USD ($) $ in Thousands		3 Months Ended	6 Months Ended	12 Months Ended
		Mar. 31, 2018	Mar. 31, 2018	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2017
Income Tax Disclosure [Abstract]
Tax at statutory rate of 35%				$ 223,202	$ 241,853	$ 293,129
Income Tax Effects Allocated Directly to Equity, Employee Stock Options				(57,519)	(50,796)	(50,314)
Effective Income Tax Rate Reconciliation, Foreign Income Tax Rate Differential, Amount				2,136	(13,770)	(29,685)
Effective income tax rate reconciliation, foreign derived intangible income, amount				(15,886)	0	0
Effective Income Tax Rate Reconciliation, Change in Deferred Tax Assets Valuation Allowance, Amount				66,101	0	0
Effective Income Tax Rate Reconciliation, Tax Credit, Foreign, Amount				18,370	2,939	0
Domestic manufacturing deduction				0	(15,091)	(17,832)
Effective Income Tax Reconciliation, Deduction for US Tax Reform Act	[1]			0	146,380	0
Other-net				(22,322)	(11,144)	(13,591)
Income tax provision				$ 221,986	$ 24,021	$ 208,889
Statutory tax rate		35.00%	24.50%	21.00%		35.00%
[1]	On December 22, 2017, the Tax Cuts and Jobs Act (the “Act”) was enacted. The Act reduces the U.S. federal corporate tax rate from 35% to 21% , requires companies to pay a one-time transition tax on earnings from certain foreign subsidiaries that were previously deferred as well as other changes. We recorded tax benefits of $176.4 million related to the remeasurement of our net U.S. deferred tax liabilities to reflect the reduction in the corporate tax rate. We also recorded tax expense of $30.0 million related to the one-time transition tax.

INCOME TAXES - Components of De

INCOME TAXES - Components of Deferred Taxes (Detail) - USD ($) $ in Thousands	Sep. 30, 2019	Sep. 30, 2018
Income Tax Disclosure [Abstract]
Intangible assets	$ (709,561)	$ (469,939)
Property, plant and equipment	(63,603)	(26,615)
Interest rate swaps	54,643	(20,052)
Unremitted foreign earnings	(7,310)	(4,488)
Employee benefits, compensation and other accrued obligations	122,777	73,906
Deferred Tax Liabilities, U.S. Interest Expense Limitation	64,968	0
Deferred Income Tax Liability, Loss Contract Reserve	62,513	12,670
Net operating losses	58,047	46,487
Inventory	39,240	20,916
Deferred Tax Assets, Tax Credit Carryforwards, Foreign	23,746	289
Deferred Tax Assets, Tax Credit Carryforwards	16,850	3,114
Environmental	9,636	8,551
Product warranties	8,394	4,471
Other	11,338	(1,557)
Total deferred tax liabilities	(308,322)	(352,247)
Add: Valuation allowance	(117,660)	(47,249)
Total net deferred tax liabilities	$ (425,982)	$ (399,496)

INCOME TAXES - Reconciliation o

INCOME TAXES - Reconciliation of Beginning and Ending Amount of Unrecognized Tax Benefits (Detail) - USD ($) $ in Thousands	12 Months Ended
	Sep. 30, 2019	Sep. 30, 2018
Reconciliation of Unrecognized Tax Benefits, Excluding Amounts Pertaining to Examined Tax Returns [Roll Forward]
Balance at beginning of period	$ 14,080	$ 8,655
Additions based on tax positions related to the prior year	25,936	4,637
Additions based on tax positions related to the current year	422	2,390
Reductions based on tax positions related to the prior year	(2,691)	(100)
Unrecognized Tax Benefits, Decrease Resulting from Settlements with Taxing Authorities	0	66
Lapse in statute of limitations	(1,238)	(1,436)
Balance at end of period	$ 36,509	$ 14,080

INCOME TAXES Income before Tax

INCOME TAXES Income before Tax from Continuing Operations (Details) - USD ($) $ in Thousands	12 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2017
Income before Tax from Continuing Operations [Abstract]
Income (Loss) from Continuing Operations before Income Taxes, Domestic	$ 877,949	$ 826,539	$ 698,201
Income (Loss) from Continuing Operations before Income Taxes, Foreign	184,916	159,018	139,229
INCOME FROM CONTINUING OPERATIONS BEFORE INCOME TAXES	$ 1,062,865	$ 985,557	$ 837,430

ENVIRONMENTAL LIABILITIES - Nar

ENVIRONMENTAL LIABILITIES - Narratives (Detail) - USD ($) $ in Millions	Sep. 30, 2019	Sep. 30, 2018
Environmental Remediation Obligations [Abstract]
Accrued Environmental Loss Contingencies, Current	$ 9.4	$ 7.3
Accrued Environmental Loss Contingencies, Noncurrent	$ 32.7	$ 31.8

CAPITAL STOCK - Narratives (Det

CAPITAL STOCK - Narratives (Detail) - USD ($)	12 Months Ended
	Sep. 30, 2017	Sep. 30, 2019	Sep. 30, 2018	Nov. 08, 2017
Shareholders Equity [Line Items]
Common stock, shares authorized		224,400,000	224,400,000
Common stock, par value		$ 0.01	$ 0.01
Preferred stock, shares authorized		149,600,000	149,600,000
Preferred stock, par value		$ 0.01	$ 0.01
Common stock, shares issued		57,623,311	56,895,686
Treasury stock, shares		4,161,326	4,161,326
Preferred stock, shares outstanding		0	0
Value of common stock repurchased	$ (389,821,000)
November 8, 2017 Stock Repurchase Program [Member]
Shareholders Equity [Line Items]
Stock Repurchase Program, Authorized Amount		$ 650,000,000		$ 650,000,000

SEGMENTS - Narratives (Detail)

SEGMENTS - Narratives (Detail)	12 Months Ended
	Sep. 30, 2019Segment
Segment Reporting [Abstract]
Number of reporting segments	3

SEGMENTS - Net Sales by Reporta

SEGMENTS - Net Sales by Reportable Segment (Detail) - USD ($) $ in Thousands	12 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2017
Segment Reporting Information [Line Items]
NET SALES	$ 5,223,203	$ 3,811,126	$ 3,504,286
Operating Segments | Power & Control
Segment Reporting Information [Line Items]
NET SALES	2,735,574	2,139,135	1,927,244
Operating Segments | Airframe
Segment Reporting Information [Line Items]
NET SALES	2,329,408	1,530,942	1,442,073
Operating Segments | Non-aviation
Segment Reporting Information [Line Items]
NET SALES	158,221	141,049	134,969
Commercial OEM [Member] | Operating Segments | Power & Control
Segment Reporting Information [Line Items]
NET SALES	547,462	498,654	460,444
Commercial OEM [Member] | Operating Segments | Airframe
Segment Reporting Information [Line Items]
NET SALES	597,765	508,671	497,612
Commercial Aftermarket [Member] | Operating Segments | Power & Control
Segment Reporting Information [Line Items]
NET SALES	710,099	665,663	606,389
Commercial Aftermarket [Member] | Operating Segments | Airframe
Segment Reporting Information [Line Items]
NET SALES	759,697	701,110	630,382
Defense [Member] | Operating Segments | Power & Control
Segment Reporting Information [Line Items]
NET SALES	1,164,545	974,818	860,411
Defense [Member] | Operating Segments | Airframe
Segment Reporting Information [Line Items]
NET SALES	389,426	321,161	314,079
Esterline [Member] | Operating Segments | Power & Control
Segment Reporting Information [Line Items]
NET SALES	313,468	0	0
Esterline [Member] | Operating Segments | Airframe
Segment Reporting Information [Line Items]
NET SALES	$ 582,520	$ 0	$ 0

SEGMENTS - EBITDA Defined by Se

SEGMENTS - EBITDA Defined by Segment to Consolidated Income Before Taxes Operations (Detail) - USD ($) $ in Thousands	12 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2017
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Earnings before interest taxes depreciation and amortization	$ 2,418,801	$ 1,876,558	$ 1,710,563
Depreciation and amortization	225,700	129,844	141,025
Interest expense, net	859,753	663,008	602,589
Stock compensation expense	93,362	58,481	45,524
Refinancing costs	3,013	6,396	39,807
Income before income taxes	1,062,865	985,557	837,430
Operating Segments
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Earnings before interest taxes depreciation and amortization	2,508,339	1,918,027	1,749,151
Operating Segments | Power & Control
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Earnings before interest taxes depreciation and amortization	1,395,085	1,114,464	980,046
Depreciation and amortization	98,366	67,721	85,681
Operating Segments | Airframe
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Earnings before interest taxes depreciation and amortization	1,062,679	759,253	726,630
Depreciation and amortization	119,259	55,732	51,440
Operating Segments | Non-aviation
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Earnings before interest taxes depreciation and amortization	50,575	44,310	42,475
Depreciation and amortization	6,280	5,276	2,745
Corporate, Non-Segment [Member]
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Earnings before interest taxes depreciation and amortization	89,538	41,469	38,588
Depreciation and amortization	1,795	1,115	1,159
Reconciling Items
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Depreciation and amortization	225,700	129,844	141,025
Interest expense, net	(859,753)	(663,008)	602,589
Acquisition-related costs	168,898	28,450	31,191
Stock compensation expense	93,362	58,481	45,524
Refinancing costs		6,396	39,807
Other nonrecurring charges	$ 5,210	$ 4,822	$ 12,997

SEGMENTS - Capital Expenditures

SEGMENTS - Capital Expenditures and Depreciation and Amortization by Segment (Detail) - USD ($) $ in Thousands	12 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2017
Segment Reporting Information [Line Items]
Capital expenditures	$ 101,591	$ 73,341	$ 71,013
Depreciation and amortization	225,700	129,844	141,025
Operating Segments | Power & Control
Segment Reporting Information [Line Items]
Capital expenditures	49,573	38,762	32,424
Depreciation and amortization	98,366	67,721	85,681
Operating Segments | Airframe
Segment Reporting Information [Line Items]
Capital expenditures	48,027	32,028	34,526
Depreciation and amortization	119,259	55,732	51,440
Operating Segments | Non-aviation
Segment Reporting Information [Line Items]
Capital expenditures	2,546	2,156	3,981
Depreciation and amortization	6,280	5,276	2,745
Corporate, Non-Segment [Member]
Segment Reporting Information [Line Items]
Capital expenditures	1,445	395	82
Depreciation and amortization	$ 1,795	$ 1,115	$ 1,159

SEGMENTS - Total Assets by Segm

SEGMENTS - Total Assets by Segment (Detail) - USD ($) $ in Thousands	Sep. 30, 2019	Sep. 30, 2018
Segment Reporting, Asset Reconciling Item [Line Items]
Total assets	$ 16,254,731	$ 12,197,467
Operating Segments | Power & Control
Segment Reporting, Asset Reconciling Item [Line Items]
Total assets	7,037,090	5,698,524
Operating Segments | Airframe
Segment Reporting, Asset Reconciling Item [Line Items]
Total assets	6,672,179	4,091,011
Operating Segments | Non-aviation
Segment Reporting, Asset Reconciling Item [Line Items]
Total assets	261,841	234,770
Corporate, Non-Segment [Member]
Segment Reporting, Asset Reconciling Item [Line Items]
Total assets	1,321,492	2,173,162
Discontinued Operations, Held-for-sale [Member]
Segment Reporting, Asset Reconciling Item [Line Items]
Total assets	$ 962,129	$ 0

STOCK-BASED COMPENSATION - Narr

STOCK-BASED COMPENSATION - Narratives (Detail) - USD ($) $ / shares in Units, $ in Thousands	1 Months Ended	12 Months Ended
	Mar. 31, 2011	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2003	Oct. 03, 2019	Oct. 02, 2014	Sep. 30, 2013
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Non-cash stock compensation		$ 93,362	$ 58,481	$ 45,524
Stock option weighted-average grant date fair value		$ 114.43	$ 81.04	$ 67.11
Unrecognized compensation cost related to non-vested awards expected to vest		$ 103,000
Fair value of options vested		$ 37,700	$ 44,400	$ 42,900
Special cash dividend paid per share (in dollars per share)		$ 30	$ 0	$ 46
Restricted stock outstanding		0
Share-based Compensation Arrangement by Share-based Payment Award, Shares Issued in Period		875
Weighted average grant date fair value, share issued		$ 476.33
Cash dividend and dividend equivalents paid		$ 80,368	$ 16,420	$ 214,849
Payments of Dividends		1,712,219	56,148	2,581,552
Dividend Equivalent Payments On Certain Stock Options, Current		63,796	24,200
Dividend Equivalent Payments on Certain Stock Options, Non-current		$ 48,300
Share-based Payment Arrangement, Nonvested Award, Cost Not yet Recognized, Period for Recognition		2 years 4 months 24 days
2014 Stock Option Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Issuance of common stock							5,000,000
2006 Stock Incentive Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Issuance of common stock	8,119,668
Shares available for award		1,797,892
Restricted stock grant period in years	3 years
2003 Stock Option Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Issuance of common stock								9,339,453
Shares available for award					3,870,152
Restricted stock grant period in years					4 years
Stock split, terms		TD Group (after giving effect to the 149.60 for 1.00 stock split effected on March 14, 2006)
Additional stock option granted					5,469,301
Stock option, expiry period					10 years
Total intrinsic value of options exercised		$ 240,200	192,500	61,100
2003 Stock Option Plan | Employee Service
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Percentage of vesting					20.00%
2003 Stock Option Plan | Other Than Employee Service
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Percentage of vesting					80.00%
Vested Options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Dividend, Share-based Payment Arrangement, Cash		$ 111,000	$ 56,100	$ 19,500
Time Vested Stock Options | 2003 Stock Option Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of Options Exercisable at end of period			0
Subsequent Event [Member] | 2019 Stock Option Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Issuance of common stock						4,000,000

STOCK-BASED COMPENSATION - Weig

STOCK-BASED COMPENSATION - Weighted Average Assumptions used to Estimate Fair Value of all Options at Grant Date using Black-Scholes-Merton Option-Pricing Model (Detail)	12 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2017
Share-based Payment Arrangement [Abstract]
Risk-free interest rate, minimum	2.33%	2.01%	1.56%
Risk-free interest rate, maximum	3.03%	2.84%	2.01%
Expected life of options	5 years 6 months	5 years 2 months 12 days	5 years
Expected dividend yield of stock	0.00%	0.00%	0.00%
Expected volatility of stock	25.00%	25.00%	25.00%

STOCK-BASED COMPENSATION - Summ

STOCK-BASED COMPENSATION - Summary of Activity, Pricing and Other Information for Performance Vested Stock-Based Award Activity (Detail) - USD ($)	12 Months Ended
	Sep. 30, 2019	Sep. 30, 2003
2014 Stock Option Plan | Performance Vested Stock Options
Number of Options
Number of Options, Outstanding, beginning of period	2,113,278
Number of Options, Granted	1,184,680
Number of Options, Exercised	(24,150)
Number of Options, Forfeited	(105,350)
Number of Options, Expired	(1,000)
Number of Options, Outstanding, end of period	3,167,458
Number of Options, Expected to vest	1,820,010
Number of Options Exercisable at end of period	824,797
Weighted average exercise price per option
Weighted-Average Exercise Price Per Option, Outstanding, beginning of period	$ 283.84
Weighted-Average Exercise Price Per Option, Granted	393.32
Weighted-Average Exercise Price Per Option, Exercised	251.22
Weighted-Average Exercise Price Per Option, Forfeited	322.71
Weighted-Average Exercise Price Per Option, Expired	303.90
Weighted-Average Exercise Price Per Option, Outstanding, end of period	323.73
Weighted-Average Exercise Price Per Option, Expected to vest	323.70
Weighted-Average Exercise Price Per Option, Exercisable	$ 315.16
Weighted average remaining contractual term
Weighted-Average Remaining Contractual Term, Outstanding, years	8 years 3 months 18 days
Weighted-Average Remaining Contractual Term, Expected to vest, years	8 years 3 months 18 days
Weighted-Average Remaining Contractual Term, Exercisable, years	8 years 2 months 12 days
Aggregate intrinsic value
Aggregate Intrinsic Value, Outstanding	$ 623,799,179
Aggregate Intrinsic Value, Expected to vest	358,483,056
Aggregate Intrinsic Value, Exercisable	$ 169,504,031
2006 Stock Incentive Plan
Number of Options
Number of Options, Granted	1,797,892
2006 Stock Incentive Plan | Performance Vested Stock Options
Number of Options
Number of Options, Outstanding, beginning of period	3,878,127
Number of Options, Granted	0
Number of Options, Exercised	(702,600)
Number of Options, Forfeited	(41,505)
Number of Options, Expired	0
Number of Options, Outstanding, end of period	3,134,022
Number of Options, Expected to vest	141,080
Number of Options Exercisable at end of period	2,995,342
Weighted average exercise price per option
Weighted-Average Exercise Price Per Option, Outstanding, beginning of period	$ 147.50
Weighted-Average Exercise Price Per Option, Granted	0
Weighted-Average Exercise Price Per Option, Exercised	107.90
Weighted-Average Exercise Price Per Option, Forfeited	223.42
Weighted-Average Exercise Price Per Option, Expired	0
Weighted-Average Exercise Price Per Option, Outstanding, end of period	155.34
Weighted-Average Exercise Price Per Option, Expected to vest	225.90
Weighted-Average Exercise Price Per Option, Exercisable	$ 152.08
Weighted average remaining contractual term
Weighted-Average Remaining Contractual Term, Outstanding, years	3 years 10 months 24 days
Weighted-Average Remaining Contractual Term, Expected to vest, years	6 years 1 month 6 days
Weighted-Average Remaining Contractual Term, Exercisable, years	3 years 9 months 18 days
Aggregate intrinsic value
Aggregate Intrinsic Value, Outstanding	$ (1,144,952,257)
Aggregate Intrinsic Value, Expected to vest	(41,586,446)
Aggregate Intrinsic Value, Exercisable	$ 1,104,053,108
2003 Stock Option Plan
Number of Options
Number of Options, Granted		3,870,152
2003 Stock Option Plan | Performance Vested Stock Options
Number of Options
Number of Options, Outstanding, beginning of period	77,829
Number of Options, Granted	0
Number of Options, Exercised	0
Number of Options, Outstanding, end of period	77,829
Number of Options Exercisable at end of period	77,829
Weighted average exercise price per option
Weighted-Average Exercise Price Per Option, Outstanding, beginning of period	$ 130.09
Weighted-Average Exercise Price Per Option, Granted	0
Weighted-Average Exercise Price Per Option, Exercised	0
Weighted-Average Exercise Price Per Option, Outstanding, end of period	130.09
Weighted-Average Exercise Price Per Option, Exercisable	$ 130.09
Weighted average remaining contractual term
Weighted-Average Remaining Contractual Term, Outstanding, years	3 years 1 month 6 days
Weighted-Average Remaining Contractual Term, Exercisable, years	3 years 1 month 6 days
Aggregate intrinsic value
Aggregate Intrinsic Value, Outstanding	$ (30,398,451)
Aggregate Intrinsic Value, Exercisable	$ 30,398,451

LEASES -Narratives (Detail)

LEASES -Narratives (Detail) - USD ($) $ in Millions	12 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2017
Leases [Abstract]
Annual rental expense	$ 25.5	$ 19.2	$ 19
Future minimum rental commitments due next twelve months	22.3
Future minimum rental commitments due in two years	31.5
Future minimum rental commitments due in three years	17.2
Future minimum rental commitments due in four years	14.1
Future minimum rental commitments due in five years	12.5
Future minimum rental commitments, due thereafter	$ 27.8

FAIR VALUE MEASUREMENTS Carryin

FAIR VALUE MEASUREMENTS Carrying Amounts and Fair Values of Financial Instruments (Detail) - USD ($) $ in Thousands	Sep. 30, 2019	Feb. 01, 2019	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2016
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Cash and cash equivalents, Assets, Carrying Amount	$ 1,467,486		$ 2,073,017	$ 650,561	$ 1,586,994
Short-term borrowings - trade receivable securitization facility, Carrying Amount	349,519		299,519
Long-term Debt	16,549,434		12,577,763
Other Noncurrent Assets
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Interest Rate Cash Flow Hedge Asset at Carrying Value	1,225		36,160
Interest Rate Swap Asset Carrying Amount	0		61,126
Foreign Currency Contract, Asset	21		0
Prepaid Expenses and Other Current Assets [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Interest Rate Swap Asset Carrying Amount	0		11,634
Foreign Currency Contract, Asset	80		0
Accrued Liabilities
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Foreign Currency Contract, Asset	6,308
Interest rate swap agreements, Liabilities, Carrying Amount	13,218		528
Other Non-Current Liabilities
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Foreign Currency Contract, Asset	403
Interest rate swap agreements, Liabilities, Carrying Amount	202,378		142
Term Loans
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term Debt	7,448,549		7,509,205
Government Refundable Advances [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term Debt	39,195		0
Long-term debt, Fair Value	39,195		0
Capital Lease Obligations [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term Debt	49,906		0
Fair Value, Inputs, Level 1 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Cash and cash equivalents, Assets, Fair Value	1,467,486		2,073,017
Fair Value, Inputs, Level 2 [Member] | Other Noncurrent Assets
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Interest Rate Cash Flow Hedge Asset at Fair Value	1,225		36,160
Interest Rate Swap Asset at Fair Value	0		61,126
Foreign Currency Contract, Asset	21
Fair Value, Inputs, Level 2 [Member] | Prepaid Expenses and Other Current Assets [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Interest Rate Swap Asset at Fair Value	0		11,634
Foreign Currency Contract, Asset	80
Fair Value, Inputs, Level 2 [Member] | Accrued Liabilities
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Foreign Currency Contract, Asset	6,308
Interest Rate Cash Flow Hedge Liability at Fair Value	13,218		528
Fair Value, Inputs, Level 2 [Member] | Other Non-Current Liabilities
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Foreign Currency Contract, Asset	403
Interest Rate Cash Flow Hedge Liability at Fair Value	202,378		142
Fair Value, Inputs, Level 2 [Member] | Term Loans
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term debt, Fair Value	7,477,552		7,607,323
Fair Value, Inputs, Level 2 [Member] | Capital Lease Obligations [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term debt, Fair Value	49,906		0
5.50% Senior Subordinated Notes, Due 2020 | Senior Subordinated Notes
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term Debt	$ 0		$ 547,813
Debt Instrument, Interest Rate, Stated Percentage	5.50%		5.50%
5.50% Senior Subordinated Notes, Due 2020 | Fair Value, Inputs, Level 1 [Member] | Senior Subordinated Notes
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term debt, Fair Value	$ 0		$ 548,625
7.50% Senior Subordinated Notes, Due 2021 | Senior Subordinated Notes
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Debt Instrument, Interest Rate, Stated Percentage	0.00%		7.50%
6.00% Senior Subordinated Notes, Due 2022 | Senior Subordinated Notes
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term Debt	$ 1,145,939		$ 1,144,499
Debt Instrument, Interest Rate, Stated Percentage	6.00%		6.00%
6.00% Senior Subordinated Notes, Due 2022 | Fair Value, Inputs, Level 1 [Member] | Senior Subordinated Notes
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term debt, Fair Value	$ 1,167,250		$ 1,155,750
6.50% Senior Subordinated Notes, Due 2024 | Senior Subordinated Notes
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term Debt	$ 1,194,310		$ 1,193,134
Debt Instrument, Interest Rate, Stated Percentage	6.50%		6.50%
6.50% Senior Subordinated Notes, Due 2024 | Fair Value, Inputs, Level 1 [Member] | Senior Subordinated Notes
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term debt, Fair Value	$ 1,239,000		$ 1,215,000
6.50% Senior Subordinated Notes, Due 2025 | Senior Subordinated Notes
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term Debt	$ 750,113		$ 750,131
Debt Instrument, Interest Rate, Stated Percentage	6.50%		6.50%
6.50% Senior Subordinated Notes, Due 2025 | Fair Value, Inputs, Level 1 [Member] | Senior Subordinated Notes
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term debt, Fair Value	$ 781,875		$ 757,500
6.375% Senior Subordinated Notes, Due 2026 | Senior Subordinated Notes
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term Debt	$ 943,210		$ 942,202
Debt Instrument, Interest Rate, Stated Percentage	6.375%		6.375%
6.375% Senior Subordinated Notes, Due 2026 | Fair Value, Inputs, Level 1 [Member] | Senior Subordinated Notes
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term debt, Fair Value	$ 998,688		$ 942,875
Senior subordinated notes due 2026 6.875% | Senior Subordinated Notes
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term Debt	$ 491,331		$ 490,779
Debt Instrument, Interest Rate, Stated Percentage	6.875%		0.00%
Senior subordinated notes due 2026 6.875% | Fair Value, Inputs, Level 1 [Member] | Senior Subordinated Notes
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term debt, Fair Value	$ 535,000		$ 507,500
Senior Secured Notes $4B Due 2026 6.25% [Member] | Secured Debt [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term Debt	3,942,182		0
Senior Secured Notes $4B Due 2026 6.25% [Member] | Fair Value, Inputs, Level 1 [Member] | Secured Debt [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term debt, Fair Value	4,290,000		0
Senior Subordinated Notes $550M Due 2027 7.50% [Member] | Senior Subordinated Notes
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term Debt	544,700		0
Long-term debt, Fair Value			0
Debt Instrument, Interest Rate, Stated Percentage		7.50%
Senior Subordinated Notes $550M Due 2027 7.50% [Member] | Fair Value, Inputs, Level 1 [Member] | Senior Subordinated Notes
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term debt, Fair Value	595,375
Asset-backed Securities
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Short-term borrowings - trade receivable securitization facility, Carrying Amount	349,519		299,519
Asset-backed Securities | Fair Value, Inputs, Level 1 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Short-term borrowings - trade receivable securitization facility, Fair Value	$ 349,519		$ 299,519

DERIVATIVES AND HEDGING ACTIV_3

DERIVATIVES AND HEDGING ACTIVITIES - Narratives (Detail) - USD ($)		12 Months Ended
		Sep. 30, 2019	Sep. 30, 2018
Interest Rate Swap and Cap
Derivative [Line Items]
Derivative loss to be recognized		$ 17,200,000
Interest Rate Cap
Derivative [Line Items]
Derivative Instruments, Gain (Loss) Reclassification from Accumulated OCI to Income, Estimated Tax to be Transferred		1,500,000
Derivative Instruments, Gain (Loss) Reclassification from Accumulated OCI to Income, Estimated Gross Amount to be Transferred		6,200,000
Foreign Exchange Forward [Member]
Derivative [Line Items]
Derivative Instruments, Gain (Loss) Reclassification from Accumulated OCI to Income, Estimated Gross Amount to be Transferred		5,300,000
Interest rate swap, notional amount		217,200,000
Accumulated Net Gain (Loss) from Cash Flow Hedges Attributable to Parent [Member] | Reclassification out of Accumulated Other Comprehensive Income [Member]
Derivative [Line Items]
Interest Expense	[1]	(3,060,000)	$ (3,443,000)
Tranche F | Interest Rate Cap
Derivative [Line Items]
Interest rate swap, notional amount		$ 400,000,000
Derivative, Cap Interest Rate		2.50%
Tranche F | Interest rate cap agreements beginning June 30, 2016
Derivative [Line Items]
Interest rate swap, notional amount		$ 400,000,000
Derivative, Cap Interest Rate		2.00%
Tranche F | Interest Rate Swap [Member]
Derivative [Line Items]
Interest rate swap, notional amount		$ 1,000,000,000
Derivative, Fixed Interest Rate		4.90%
Tranche F | Interest rate swap June 28, 2016 [Member]
Derivative [Line Items]
Derivative, Fixed Interest Rate		4.30%
Tranche F | Interest rate swap beginning June 30, 2021 [Member]
Derivative [Line Items]
Interest rate swap, notional amount		$ 1,400,000,000
Derivative, Fixed Interest Rate		5.50%
Tranche F | Interest rate swap June 28, 2019 [Member]
Derivative [Line Items]
Interest rate swap, notional amount		$ 1,000,000,000
Tranche E | Interest Rate Cap
Derivative [Line Items]
Interest rate swap, notional amount		750,000,000
Tranche E | Interest rate cap beginning September 30, 2015
Derivative [Line Items]
Interest rate swap, notional amount		$ 750,000,000
Derivative, Cap Interest Rate		2.50%
Tranche E | Interest rate swap beginning June 30, 2020 [Member]
Derivative [Line Items]
Interest rate swap, notional amount		$ 750,000,000
Derivative, Fixed Interest Rate		5.00%
Tranche E | Interest rate swap beginning March 31, 2016 [Member]
Derivative [Line Items]
Interest rate swap, notional amount		$ 750,000,000
Derivative, Fixed Interest Rate		5.30%
Tranche G [Member] | Interest Rate Cap
Derivative [Line Items]
Interest rate swap, notional amount		$ 400,000,000
Tranche G [Member] | Interest Rate Swap [Member]
Derivative [Line Items]
Interest rate swap, notional amount		$ 500,000,000
Derivative, Fixed Interest Rate		4.40%
Tranche G [Member] | Interest rate swap beginning September 30, 2017 [Member]
Derivative [Line Items]
Interest rate swap, notional amount		$ 400,000,000
Derivative, Fixed Interest Rate		4.40%
Tranche G [Member] | Interest rate swap beginning December 31, 2021 [Member]
Derivative [Line Items]
Interest rate swap, notional amount		$ 900,000,000
Derivative, Fixed Interest Rate		5.60%
Tranche G [Member] | Interest rate swap beginning September 30, 2022 [Member]
Derivative [Line Items]
Interest rate swap, notional amount		$ 400,000,000
Derivative, Fixed Interest Rate		5.50%
September 30, 2016 Redesignation [Member] | Accumulated Net Gain (Loss) from Cash Flow Hedges Attributable to Parent [Member] | Reclassification out of Accumulated Other Comprehensive Income [Member]
Derivative [Line Items]
Interest Expense		$ 4,800,000	4,000,000
December 30, 2017 Redesignation [Member] | Interest Rate Swap [Member]
Derivative [Line Items]
Derivative Instruments, Gain (Loss) Reclassification from Accumulated OCI to Income, Estimated Tax to be Transferred		400,000
Derivative Instruments, Gain (Loss) Reclassification from Accumulated OCI to Income, Estimated Gross Amount to be Transferred		1,700,000
December 30, 2017 Redesignation [Member] | Accumulated Net Gain (Loss) from Cash Flow Hedges Attributable to Parent [Member] | Reclassification out of Accumulated Other Comprehensive Income [Member]
Derivative [Line Items]
Interest Expense		1,100,000	800,000
March 31, 2018 Redesignation [Member] | Interest Rate Swap [Member]
Derivative [Line Items]
Derivative Instruments, Gain (Loss) Reclassification from Accumulated OCI to Income, Estimated Tax to be Transferred		2,000,000
Derivative Instruments, Gain (Loss) Reclassification from Accumulated OCI to Income, Estimated Gross Amount to be Transferred		8,600,000
March 31, 2018 Redesignation [Member] | Accumulated Net Gain (Loss) from Cash Flow Hedges Attributable to Parent [Member] | Reclassification out of Accumulated Other Comprehensive Income [Member]
Derivative [Line Items]
Interest Income, Other		2,800,000	$ 1,400,000
Sales [Member]
Derivative [Line Items]
Foreign Currency Cash Flow Hedge Gain (Loss) Reclassified to Earnings, Net		400,000
Selling, General and Administrative Expenses [Member]
Derivative [Line Items]
Gain (Loss) on foreign currency contracts not designated as accounting hedges		$ 100,000
[1]	This component of accumulated other comprehensive (loss) income is included in interest expense (see Note 21, “Derivatives and Hedging Activities,” for additional information).

DERIVATIVES AND HEDGING ACTIV_4

DERIVATIVES AND HEDGING ACTIVITIES - Schedule of Interest Rate Derivatives (Details) - USD ($)		Sep. 30, 2019	Sep. 30, 2018
Derivative [Line Items]
Derivative Asset, Fair Value, Gross Asset		$ 1,225,000	$ 108,250,000
Derivative Asset, Fair Value, Gross Liability		(215,596,000)	0
Derivative Asset, Collateral, Obligation to Return Cash, Offset		0	670,000
Derivative Liability, Collateral, Right to Reclaim Cash, Offset		0	(670,000)
Derivative Asset	[1]	1,225,000	108,920,000
Derivative Liability	[1]	(215,596,000)	(670,000)
Interest Rate Cap
Derivative [Line Items]
Derivative Asset, Fair Value, Gross Asset		1,225,000	36,160,000
Derivative Asset, Fair Value, Gross Liability		0	0
Interest Rate Swap [Member]
Derivative [Line Items]
Derivative Asset, Fair Value, Gross Asset	[2]	0	72,090,000
Derivative Asset, Fair Value, Gross Liability	[2]	(215,596,000)	$ 0
Tranche F | Interest rate swap beginning June 30, 2021 [Member]
Derivative [Line Items]
Interest rate swap, notional amount		$ 1,400,000,000
Derivative, Fixed Interest Rate		5.50%
Derivative, Variable Interest Rate		3.00%
Derivative, Basis Spread on Variable Rate		2.50%
Tranche F | Interest Rate Cap
Derivative [Line Items]
Interest rate swap, notional amount		$ 400,000,000
Derivative, Cap Interest Rate		2.50%
Tranche F | Interest rate cap agreements beginning June 30, 2016
Derivative [Line Items]
Interest rate swap, notional amount		$ 400,000,000
Derivative, Cap Interest Rate		2.00%
Tranche F | Interest rate swap June 28, 2016 [Member]
Derivative [Line Items]
Derivative, Fixed Interest Rate		4.30%
Derivative, Variable Interest Rate		1.80%
Derivative, Basis Spread on Variable Rate		2.50%
Tranche F | Interest Rate Swap [Member]
Derivative [Line Items]
Interest rate swap, notional amount		$ 1,000,000,000
Derivative, Fixed Interest Rate		4.90%
Tranche G [Member] | Interest Rate Cap
Derivative [Line Items]
Interest rate swap, notional amount		$ 400,000,000
Tranche G [Member] | Interest rate swap beginning September 30, 2017 [Member]
Derivative [Line Items]
Interest rate swap, notional amount		$ 400,000,000
Derivative, Fixed Interest Rate		4.40%
Derivative, Variable Interest Rate		1.90%
Derivative, Basis Spread on Variable Rate		2.50%
Tranche G [Member] | Interest Rate Swap [Member]
Derivative [Line Items]
Interest rate swap, notional amount		$ 500,000,000
Derivative, Fixed Interest Rate		4.40%
Derivative, Variable Interest Rate		1.90%
Derivative, Basis Spread on Variable Rate		2.50%
Tranche G [Member] | Interest rate swap beginning December 31, 2021 [Member]
Derivative [Line Items]
Interest rate swap, notional amount		$ 900,000,000
Derivative, Fixed Interest Rate		5.60%
Derivative, Variable Interest Rate		3.10%
Derivative, Basis Spread on Variable Rate		2.50%
Tranche G [Member] | Interest rate swap beginning September 30, 2022 [Member]
Derivative [Line Items]
Interest rate swap, notional amount		$ 400,000,000
Derivative, Fixed Interest Rate		5.50%
Derivative, Variable Interest Rate		3.00%
Derivative, Basis Spread on Variable Rate		2.50%
Tranche E | Interest Rate Cap
Derivative [Line Items]
Interest rate swap, notional amount		$ 750,000,000
Tranche E | Interest Rate Cap [Member]
Derivative [Line Items]
Interest rate swap, notional amount		750,000,000
Tranche E | Interest rate cap beginning September 30, 2015
Derivative [Line Items]
Interest rate swap, notional amount		$ 750,000,000
Derivative, Cap Interest Rate		2.50%
Tranche E | Interest rate swap beginning June 30, 2020 [Member]
Derivative [Line Items]
Interest rate swap, notional amount		$ 750,000,000
Derivative, Fixed Interest Rate		5.00%
Derivative, Variable Interest Rate		2.50%
Derivative, Basis Spread on Variable Rate		2.50%
Tranche E | Interest rate swap beginning June 30, 2022 [Member]
Derivative [Line Items]
Interest rate swap, notional amount		$ 1,500,000,000
Derivative, Fixed Interest Rate		5.60%
Derivative, Variable Interest Rate		3.10%
Derivative, Basis Spread on Variable Rate		2.50%
Tranche E | Interest rate swap beginning March 31, 2016 [Member]
Derivative [Line Items]
Interest rate swap, notional amount		$ 750,000,000
Derivative, Fixed Interest Rate		5.30%
Derivative, Variable Interest Rate		2.80%
Derivative, Basis Spread on Variable Rate		2.50%
Tranche E | Interest rate swap beginning June 29, 2018 [Member]
Derivative [Line Items]
Interest rate swap, notional amount		$ 500,000,000
Derivative, Fixed Interest Rate		5.50%
Derivative, Variable Interest Rate		3.00%
Derivative, Basis Spread on Variable Rate		2.50%
[1]	Refer to Note 20, "Fair Value Measurements," for the consolidated balance sheet classification of our interest rate swap and cap agreements.
[2]	The increase in the interest rate swap liability is primarily attributable to a downward trend in the LIBO rate during fiscal 2019.

DERIVATIVES AND HEDGING ACTIV_5

DERIVATIVES AND HEDGING ACTIVITIES - Schedule of Notional Amounts (Details)	Sep. 30, 2019USD ($)
Tranche G [Member] | Interest Rate Swap [Member]
Derivative [Line Items]
Interest rate swap, notional amount	$ 500,000,000
Tranche G [Member] | Interest Rate Cap
Derivative [Line Items]
Interest rate swap, notional amount	400,000,000
Tranche F | Interest Rate Swap [Member]
Derivative [Line Items]
Interest rate swap, notional amount	1,000,000,000
Tranche F | Interest Rate Cap
Derivative [Line Items]
Interest rate swap, notional amount	$ 400,000,000

ACCUMULATED OTHER COMPREHENSI_3

ACCUMULATED OTHER COMPREHENSIVE LOSS - Schedule of Accumulated Other Comprehensive Loss (Detail) - USD ($) $ in Thousands		6 Months Ended	12 Months Ended
		Mar. 31, 2018	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2017
Accumulated Other Comprehensive Income (Loss) [Line Items]
Cumulative Effect of ASU 2018-02, adopted October 1, 2018			$ (2,199)
Other Comprehensive Income (Loss), Derivatives Qualifying as Hedges, Tax			(69,660)	$ 33,923	$ 20,663
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Balance at beginning of period		$ (85,143)	4,100	(85,143)
Other comprehensive loss before reclassification			(384,636)	86,609
Amounts reclassified from AOCI related to interest rate swap agreements	[1]		3,754	2,634
Interest rate swaps and caps, net of tax			(239,221)	93,860	34,471
Pension liability adjustments, net of tax			(29,004)	5,636	7,932
Foreign currency translation adjustments			(114,856)	(10,253)	22,241
Other comprehensive (loss) income, net of tax, attributable to TD Group			(383,081)	89,243	64,644
Balance at end of period			(378,981)	4,100	(85,143)
Other Comprehensive (Income) Loss, Defined Benefit Plan, after Reclassification Adjustment, Tax			8,513	(1,487)	(4,130)
INCOME TAX PROVISION			221,986	24,021	208,889
Net income including noncontrolling interests			891,311	957,062	596,887
Unrealized (loss) gain on derivatives designated and qualifying as cash flow hedges (2)
Accumulated Other Comprehensive Income (Loss) [Line Items]
Cumulative Effect of ASU 2018-02, adopted October 1, 2018	[1]		(2,199)
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Balance at beginning of period	[1]	(26,669)	67,191	(26,669)
Other comprehensive loss before reclassification	[1]		(240,776)	91,226
Amounts reclassified from AOCI related to interest rate swap agreements	[1]		3,754	2,634
Interest rate swaps and caps, net of tax	[1]		(239,221)	93,860
Balance at end of period	[1]		(172,030)	67,191	(26,669)
Defined benefit pension plan activity (3)
Accumulated Other Comprehensive Income (Loss) [Line Items]
Cumulative Effect of ASU 2018-02, adopted October 1, 2018	[2]		0
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Balance at beginning of period	[2]	(16,365)	(10,729)	(16,365)
Other comprehensive loss before reclassification	[2]		(29,004)	5,636
Amounts reclassified from AOCI related to interest rate swap agreements	[2]		0	0
Pension liability adjustments, net of tax	[2]		(29,004)	5,636
Balance at end of period	[2]		(39,733)	(10,729)	(16,365)
Currency translation adjustment
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Balance at beginning of period		(42,109)	(52,362)	(42,109)
Other comprehensive loss before reclassification			(114,856)	(10,253)
Amounts reclassified from AOCI related to interest rate swap agreements			0	0
Foreign currency translation adjustments			(114,856)	(10,253)
Balance at end of period			(167,218)	(52,362)	$ (42,109)
Reclassification out of Accumulated Other Comprehensive Income [Member] | Unrealized (loss) gain on derivatives designated and qualifying as cash flow hedges (2)
Accumulated Other Comprehensive Income (Loss) [Line Items]
Interest Expense	[3]		(3,060)	(3,443)
Losses from settlement of foreign currency forward contracts	[4]		(20)	0
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
INCOME TAX PROVISION			(714)	$ 809
Net income including noncontrolling interests		$ 2,634	3,754
Accounting Standards Update 2018-02 [Member] | Currency translation adjustment
Accumulated Other Comprehensive Income (Loss) [Line Items]
Cumulative Effect of ASU 2018-02, adopted October 1, 2018			$ 0
[1]	Unrealized gain (loss) represents derivative instruments, net of taxes of $69,660 , $(33,923) and $(20,663) for the fiscal years ended September 30, 2019 , 2018 and 2017 , respectively.
[2]	Defined benefit pension plan and other post-retirement plan activity represents pension liability adjustments, net of taxes of $8,513 , $(1,487) and $(4,130) for the fiscal years ended September 30, 2019 , 2018 and 2017 , respectively.
[3]	This component of accumulated other comprehensive (loss) income is included in interest expense (see Note 21, “Derivatives and Hedging Activities,” for additional information).
[4]	This component of accumulated other comprehensive (loss) income is included in net sales (see Note 21, “Derivatives and Hedging Activities,” for additional information).

DISCONTINUED OPERATIONS - Narra

DISCONTINUED OPERATIONS - Narrative (Details) - USD ($) $ in Thousands	Sep. 20, 2019	Jan. 26, 2018	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2017
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Cash Provided by (Used in) Investing Activities, Discontinued Operations			$ 10,600
Assets held-for-sale			962,129	$ 0
Liabilities held-for-sale			156,739	0
INCOME (LOSS) FROM DISCONTINUED OPERATIONS, NET OF TAX			50,432	(4,474)	$ (31,654)
Cash Provided by (Used in) Operating Activities, Discontinued Operations			35,300
Schroth [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Loss on classification as held-for-sale before income taxes					32,000
Business Acquisition Purchase Price Adjustment				300
Souriau Sunbank [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Disposal Group, Including Discontinued Operation, Cash and Cash Equivalents			28,545
Disposal Group, Including Discontinued Operation, Accounts, Notes and Loans Receivable, Net			66,619
Disposal Group, Including Discontinued Operation, Inventory			87,919
Disposal Group, Including Discontinued Operation, Prepaid and Other Assets			1,740
Disposal Group, Including Discontinued Operation, Property, Plant and Equipment			100,759
Disposal Group, Including Discontinued Operation, Goodwill			480,310
Disposal Group, Including Discontinued Operation, Intangible Assets			194,483
Disposal Group, Including Discontinued Operation, Other Assets			1,754
Assets held-for-sale			962,129
Disposal Group, Including Discontinued Operation, Accounts Payable			33,338
Disposal Group, Including Discontinued Operation, Accrued Liabilities			55,031
Disposal Group, including discontinued operations, Long-term Debt			5,793
Disposal Group, Including Discontinued Operation, Deferred Tax Liabilities			41,769
Disposal Group, Including Discontinued Operation, Other Liabilities			20,808
Liabilities held-for-sale			156,739
Divestiture, Sale Price			920,000
INCOME (LOSS) FROM DISCONTINUED OPERATIONS, NET OF TAX			(3,020)
Schroth [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Divestiture, Sale Price		$ 61,400		61,400
Loss on classification as held-for-sale before income taxes				0	32,000
INCOME (LOSS) FROM DISCONTINUED OPERATIONS, NET OF TAX				$ (4,474)	$ (31,654)
Esterline Interface Technology Group [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Divestiture, Sale Price	$ 190,000
Souriau Sunbank and EIT [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
INCOME (LOSS) FROM DISCONTINUED OPERATIONS, NET OF TAX			$ 50,432

DISCONTINUED OPERATIONS - Sched

DISCONTINUED OPERATIONS - Schedule of Discontinued Operations (Details) - USD ($) $ in Thousands	12 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2017
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
NET SALES	$ 5,223,203	$ 3,811,126	$ 3,504,286
Net loss from discontinued operations	50,432	(4,474)	(31,654)
Schroth [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
NET SALES		11,808	24,590
Income (loss) from discontinued operations before income taxes		354	(5,709)
Loss on classification as held-for-sale before income taxes		0	(32,000)
Income tax benefit		2,016	6,055
Income (loss) from discontinued operations before gain or loss on disposal net of tax		2,370	(31,654)
Discontinued Operation, Gain (Loss) on Disposal of Discontinued Operation, Net of Tax		(6,844)	0
Net loss from discontinued operations		$ (4,474)	$ (31,654)
Souriau Sunbank and EIT [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
NET SALES	293,975
Income (loss) from discontinued operations before income taxes	(64)
Income tax benefit	13,123
Income (loss) from discontinued operations before gain or loss on disposal net of tax	13,059
Discontinued Operation, Gain (Loss) on Disposal of Discontinued Operation, Net of Tax	37,619
Income (Loss) from Discontinued Operations, Net of Tax, Attributable to Noncontrolling Interest	(246)
Net loss from discontinued operations	50,432
Souriau Sunbank [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
NET SALES	199,356
Income (loss) from discontinued operations before income taxes	(17,176)
Income tax benefit	14,254
Income (loss) from discontinued operations before gain or loss on disposal net of tax	(2,922)
Discontinued Operation, Gain (Loss) on Disposal of Discontinued Operation, Net of Tax	0
Income (Loss) from Discontinued Operations, Net of Tax, Attributable to Noncontrolling Interest	(98)
Net loss from discontinued operations	(3,020)
EIT [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
NET SALES	94,619
Income (loss) from discontinued operations before income taxes	17,112
Income tax benefit	(1,131)
Income (loss) from discontinued operations before gain or loss on disposal net of tax	15,981
Discontinued Operation, Gain (Loss) on Disposal of Discontinued Operation, Net of Tax	37,619
Income (Loss) from Discontinued Operations, Net of Tax, Attributable to Noncontrolling Interest	(148)
Net loss from discontinued operations	$ 53,452

COMMITMENTS AND CONTINGENCIES_2

COMMITMENTS AND CONTINGENCIES (Details) $ in Millions	12 Months Ended
	Sep. 30, 2019USD ($)
Commitments and Contingencies Disclosure [Abstract]
Insurance deductible	$ 1
Fire Related Expense	$ 2.4

QUARTERLY FINANCIAL DATA (UNA_3

QUARTERLY FINANCIAL DATA (UNAUDTIED) - Schedule of Quarterly Financial Data (Unaudited) (Detail) - USD ($) $ / shares in Units, $ in Thousands		3 Months Ended																12 Months Ended
		Sep. 30, 2019		Jun. 29, 2019		Mar. 30, 2019		Dec. 29, 2018		Sep. 30, 2018		Jun. 30, 2018		Mar. 31, 2018		Dec. 30, 2017		Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2017
Quarterly Financial Data [Line Items]
NET SALES																		$ 5,223,203	$ 3,811,126	$ 3,504,286
Gross Profit																		2,809,271	2,177,510	1,984,627
INCOME FROM CONTINUING OPERATIONS INCLUDING NONCONTROLLING INTERESTS																		840,879	961,536	628,541
Net loss from discontinued operations																		50,432	(4,474)	(31,654)
NET INCOME ATTRIBUTABLE TO TD GROUP																		$ 889,770	$ 957,062	$ 596,887
Net earnings per share from continuing operations—basic and diluted																		$ 12.94	$ 16.28	$ 8.45
Net earnings (loss) per share from discontinued operations—basic and diluted																		0.90	(0.08)	(0.57)
Net earnings per share - basic and diluted																		$ 13.84	$ 16.20	$ 7.88
TransDigm Group
Quarterly Financial Data [Line Items]
NET SALES		$ 1,541,320	[1],[2]	$ 1,521,061	[1],[2]	$ 1,167,520	[1],[2]	$ 993,302	[1],[2]	$ 1,049,434	[1],[2]	$ 980,662	[1],[2]	$ 933,070	[1],[2]	$ 847,960	[1],[2]	$ 0	$ 0	$ 0
Gross Profit		882,082	[1],[2]	713,109	[1],[2]	649,964	[1],[2]	564,116	[1],[2]	597,266	[1],[2]	569,520	[1],[2]	534,074	[1],[2]	476,650	[1],[2]	0	0	0
INCOME FROM CONTINUING OPERATIONS INCLUDING NONCONTROLLING INTERESTS		317,157		127,659		200,021		196,042		230,294		217,391		201,840		312,011		889,770	957,062	596,887
Net loss from discontinued operations		30,870		16,951		2,611		0		(1,531)		(145)		(5,562)		2,764		0	0	0
Income (Loss) from Continuing Operations, Net of Tax, Attributable to Noncontrolling Interest		(1,157)		(160)		(224)		0
NET INCOME ATTRIBUTABLE TO TD GROUP		$ 346,870	[1],[2]	$ 144,450	[1],[2]	$ 202,408	[1],[2]	$ 196,042	[1],[2]	$ 228,763	[1],[2]	$ 217,246	[1],[2]	$ 196,278	[1],[2]	$ 314,775	[1],[2]	$ 889,770	$ 957,062	$ 596,887
Net earnings per share from continuing operations—basic and diluted	[1],[3]	$ 4.08		$ 2.27		$ 3.55		$ 3.05		$ 4.14		$ 3.91		$ 3.63		$ 4.60
Net earnings (loss) per share from discontinued operations—basic and diluted	[1],[3]	0.55		0.30		0.05		0		(0.03)		0		(0.10)		0.05
Net earnings per share - basic and diluted	[1]	$ 4.63	[3]	$ 2.57	[3]	$ 3.60	[2]	$ 3.05	[3]	$ 4.11	[3]	$ 3.91	[3]	$ 3.53	[3]	$ 4.65	[3]
[1]	Results adjusted to reflect amounts reclassified to discontinued operations due to the Company’s classification of Souriau-Sunbank and EIT at September 30, 2019, and Schroth at September 30, 2017, as discontinued operations. See Note 23, “Discontinued Operations,” for additional information.
[2]	The Company’s operating results include the results of operations of acquisitions from the effective date of each acquisition. See Note 2 “Acquisitions and Divestitures,” for additional details.
[3]	The sum of the earnings per share for the four quarters in a year does not necessarily equal the total year earnings per share due to the weighted average number of shares outstanding in each quarter.

SUBSEQUENT EVENTS (Details)

SUBSEQUENT EVENTS (Details) - USD ($) $ in Thousands	Oct. 29, 2019	Sep. 30, 2019	Sep. 30, 2018
Subsequent Event [Line Items]
Long-term Debt, Gross		$ 16,712,607	$ 12,699,932
Senior Subordinated Notes | Senior Subordinated Notes $2650M Due 2027 5.50% [Member] | Subsequent Event [Member]
Subsequent Event [Line Items]
Long-term Debt, Gross	$ 2,650,000
Debt Instrument, Interest Rate, Stated Percentage	5.50%
Debt Instrument, Redemption Price, Percentage	100.00%
Senior Subordinated Notes | 6.00% Senior Subordinated Notes, Due 2022
Subsequent Event [Line Items]
Long-term Debt, Gross		$ 1,150,000	$ 1,150,000
Debt Instrument, Interest Rate, Stated Percentage		6.00%	6.00%
Senior Subordinated Notes | 6.00% Senior Subordinated Notes, Due 2022 | Subsequent Event [Member]
Subsequent Event [Line Items]
Subordinated Notes Redemption, Amount	$ 1,150,000

SUPPLEMENTAL GUARANTOR INFORM_3

SUPPLEMENTAL GUARANTOR INFORMATION - Narratives (Details)	Sep. 30, 2019
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Noncontrolling Interest, Ownership Percentage by Parent	100.00%

SUPPLEMENTAL GUARANTOR INFORM_4

SUPPLEMENTAL GUARANTOR INFORMATION - Supplemental Condensed Consolidating Balance Sheet (Detail) - USD ($) $ in Thousands	Sep. 30, 2019	Oct. 01, 2018	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2016
Condensed Balance Sheet Statements, Captions [Line Items]
Cash and cash equivalents	$ 1,467,486		$ 2,073,017	$ 650,561	$ 1,586,994
Trade accounts receivable—Net	1,067,603		704,310
Inventories—Net	1,232,649	$ 801,315	805,292
Assets held-for-sale	962,129		0
Prepaid expenses and other	135,380		74,668
Total current assets	4,865,247		3,657,287
INVESTMENT IN SUBSIDIARIES AND INTERCOMPANY BALANCES	0		0
PROPERTY, PLANT AND EQUIPMENT—NET	756,757		388,333
GOODWILL	7,820,103		6,223,290	5,745,338
OTHER INTANGIBLE ASSETS—NET	2,743,820		1,788,404
OTHER	68,804		140,153
TOTAL ASSETS	16,254,731		12,197,467
Current portion of long-term debt	80,213		75,817
Short-term borrowings—trade receivable securitization facility	349,519		299,519
Accounts payable	276,590		173,603
Accrued liabilities	675,695		351,443
Liabilities held-for-sale	156,739		0
Total current liabilities	1,538,756		900,382
LONG-TERM DEBT	16,469,221		12,501,946
DEFERRED INCOME TAXES	440,817	$ 400,507	399,496
OTHER NON-CURRENT LIABILITIES	691,020		204,114
Total liabilities	19,139,814		14,005,938
Total stockholders’ deficit	(2,894,905)		(1,808,471)	(2,951,204)	(651,490)
NONCONTROLLING INTERESTS	9,822		0
TOTAL LIABILITIES AND STOCKHOLDERS’ DEFICIT	16,254,731		12,197,467
TransDigm Group
Condensed Balance Sheet Statements, Captions [Line Items]
Cash and cash equivalents	29		389	2,416	13,560
Trade accounts receivable—Net	0		0
Inventories—Net	0		0
Assets held-for-sale	0
Prepaid expenses and other	0		0
Total current assets	29		389
INVESTMENT IN SUBSIDIARIES AND INTERCOMPANY BALANCES	(2,894,934)		(1,808,860)
PROPERTY, PLANT AND EQUIPMENT—NET	0		0
GOODWILL	0		0
OTHER INTANGIBLE ASSETS—NET	0		0
OTHER	0		0
TOTAL ASSETS	(2,894,905)		(1,808,471)
Current portion of long-term debt	0		0
Short-term borrowings—trade receivable securitization facility	0		0
Accounts payable	0		0
Accrued liabilities	0		0
Liabilities held-for-sale	0
Total current liabilities	0		0
LONG-TERM DEBT	0		0
DEFERRED INCOME TAXES	0		0
OTHER NON-CURRENT LIABILITIES	0		0
Total liabilities	0		0
Total stockholders’ deficit	(2,894,905)		(1,808,471)
NONCONTROLLING INTERESTS	0		0
TOTAL LIABILITIES AND STOCKHOLDERS’ DEFICIT	(2,894,905)		(1,808,471)
TransDigm Inc.
Condensed Balance Sheet Statements, Captions [Line Items]
Cash and cash equivalents	1,092,209		1,821,437	439,473	1,421,251
Trade accounts receivable—Net	0		0
Inventories—Net	52,291		45,262
Assets held-for-sale	0
Prepaid expenses and other	27,175		16,231
Total current assets	1,171,675		1,882,930
INVESTMENT IN SUBSIDIARIES AND INTERCOMPANY BALANCES	14,729,513		10,459,497
PROPERTY, PLANT AND EQUIPMENT—NET	16,971		15,562
GOODWILL	82,924		97,002
OTHER INTANGIBLE ASSETS—NET	25,444		31,362
OTHER	5,364		104,633
TOTAL ASSETS	16,031,891		12,590,986
Current portion of long-term debt	75,688		75,817
Short-term borrowings—trade receivable securitization facility	0		0
Accounts payable	16,517		18,470
Accrued liabilities	215,562		118,600
Liabilities held-for-sale	0
Total current liabilities	307,767		212,887
LONG-TERM DEBT	15,893,314		12,011,166
DEFERRED INCOME TAXES	0		345,357
OTHER NON-CURRENT LIABILITIES	315,262		77,573
Total liabilities	16,516,343		12,646,983
Total stockholders’ deficit	(484,452)		(55,997)
NONCONTROLLING INTERESTS	0		0
TOTAL LIABILITIES AND STOCKHOLDERS’ DEFICIT	16,031,891		12,590,986
TransDigm UK
Condensed Balance Sheet Statements, Captions [Line Items]
Cash and cash equivalents	280		125	0	0
Trade accounts receivable—Net	0		0
Inventories—Net	0		0
Assets held-for-sale	0
Prepaid expenses and other	0		0
Total current assets	280		125
INVESTMENT IN SUBSIDIARIES AND INTERCOMPANY BALANCES	974,663		1,099,886
PROPERTY, PLANT AND EQUIPMENT—NET	0		0
GOODWILL	0		0
OTHER INTANGIBLE ASSETS—NET	0		0
OTHER	0		0
TOTAL ASSETS	974,943		1,100,011
Current portion of long-term debt	0		0
Short-term borrowings—trade receivable securitization facility	0		0
Accounts payable			0
Accrued liabilities	12,892		13,274
Liabilities held-for-sale	0
Total current liabilities	12,892		13,274
LONG-TERM DEBT	491,331		490,780
DEFERRED INCOME TAXES	0		0
OTHER NON-CURRENT LIABILITIES	0		0
Total liabilities	504,223		504,054
Total stockholders’ deficit	470,720		595,957
NONCONTROLLING INTERESTS	0		0
TOTAL LIABILITIES AND STOCKHOLDERS’ DEFICIT	974,943		1,100,011
Subsidiary Guarantors
Condensed Balance Sheet Statements, Captions [Line Items]
Cash and cash equivalents	(12,263)		(1,763)	(203)	8,808
Trade accounts receivable—Net	172,099		40,916
Inventories—Net	879,681		648,574
Assets held-for-sale	206,419
Prepaid expenses and other	45,220		47,020
Total current assets	1,291,156		734,747
INVESTMENT IN SUBSIDIARIES AND INTERCOMPANY BALANCES	16,373,195		8,928,726
PROPERTY, PLANT AND EQUIPMENT—NET	513,337		319,567
GOODWILL	5,544,529		5,466,148
OTHER INTANGIBLE ASSETS—NET	2,063,944		1,514,983
OTHER	33,931		29,805
TOTAL ASSETS	25,820,092		16,993,976
Current portion of long-term debt	1,020		0
Short-term borrowings—trade receivable securitization facility	0		0
Accounts payable	160,793		115,735
Accrued liabilities	237,026		162,618
Liabilities held-for-sale	22,306
Total current liabilities	421,145		278,353
LONG-TERM DEBT	49,240		0
DEFERRED INCOME TAXES	346,456		(2,329)
OTHER NON-CURRENT LIABILITIES	232,520		104,829
Total liabilities	1,049,361		380,853
Total stockholders’ deficit	24,770,731		16,613,123
NONCONTROLLING INTERESTS	0		0
TOTAL LIABILITIES AND STOCKHOLDERS’ DEFICIT	25,820,092		16,993,976
Non-Guarantor Subsidiaries
Condensed Balance Sheet Statements, Captions [Line Items]
Cash and cash equivalents	387,231		252,829	208,875	143,375
Trade accounts receivable—Net	895,504		663,394
Inventories—Net	315,966		115,913
Assets held-for-sale	755,710
Prepaid expenses and other	62,985		11,417
Total current assets	2,417,396		1,043,553
INVESTMENT IN SUBSIDIARIES AND INTERCOMPANY BALANCES	6,898,707		2,160,236
PROPERTY, PLANT AND EQUIPMENT—NET	226,449		53,204
GOODWILL	2,192,650		660,140
OTHER INTANGIBLE ASSETS—NET	654,432		242,059
OTHER	29,509		5,715
TOTAL ASSETS	12,419,143		4,164,907
Current portion of long-term debt	3,505		0
Short-term borrowings—trade receivable securitization facility	349,519		299,519
Accounts payable	99,280		39,398
Accrued liabilities	210,215		56,951
Liabilities held-for-sale	134,433
Total current liabilities	796,952		395,868
LONG-TERM DEBT	35,336		0
DEFERRED INCOME TAXES	94,361		56,468
OTHER NON-CURRENT LIABILITIES	143,238		21,712
Total liabilities	1,069,887		474,048
Total stockholders’ deficit	11,339,434		3,690,859
NONCONTROLLING INTERESTS	9,822		0
TOTAL LIABILITIES AND STOCKHOLDERS’ DEFICIT	12,419,143		4,164,907
Eliminations
Condensed Balance Sheet Statements, Captions [Line Items]
Cash and cash equivalents	0		0	$ 0	$ 0
Trade accounts receivable—Net	0		0
Inventories—Net	(15,289)		(4,457)
Assets held-for-sale	0
Prepaid expenses and other	0		0
Total current assets	(15,289)		(4,457)
INVESTMENT IN SUBSIDIARIES AND INTERCOMPANY BALANCES	(36,081,144)		(20,839,485)
PROPERTY, PLANT AND EQUIPMENT—NET	0		0
GOODWILL	0		0
OTHER INTANGIBLE ASSETS—NET	0		0
OTHER	0		0
TOTAL ASSETS	(36,096,433)		(20,843,942)
Current portion of long-term debt	0		0
Short-term borrowings—trade receivable securitization facility	0		0
Accounts payable	0		0
Accrued liabilities	0		0
Liabilities held-for-sale	0
Total current liabilities	0		0
LONG-TERM DEBT	0		0
DEFERRED INCOME TAXES	0		0
OTHER NON-CURRENT LIABILITIES	0		0
Total liabilities	0		0
Total stockholders’ deficit	(36,096,433)		(20,843,942)
NONCONTROLLING INTERESTS	0		0
TOTAL LIABILITIES AND STOCKHOLDERS’ DEFICIT	$ (36,096,433)		$ (20,843,942)

SUPPLEMENTAL GUARANTOR INFORM_5

SUPPLEMENTAL GUARANTOR INFORMATION - Supplemental Condensed Consolidating Statement of Income and Comprehensive Income (Detail) - USD ($) $ in Thousands	3 Months Ended																12 Months Ended
	Sep. 30, 2019		Jun. 29, 2019		Mar. 30, 2019		Dec. 29, 2018		Sep. 30, 2018		Jun. 30, 2018		Mar. 31, 2018		Dec. 30, 2017		Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2017
Condensed Income Statements, Captions [Line Items]
NET SALES																	$ 5,223,203	$ 3,811,126	$ 3,504,286
COST OF SALES																	2,413,932	1,633,616	1,519,659
GROSS PROFIT																	2,809,271	2,177,510	1,984,627
SELLING AND ADMINISTRATIVE EXPENSES																	747,773	449,676	412,555
AMORTIZATION OF INTANGIBLE ASSETS																	134,952	72,454	89,226
(LOSS) INCOME FROM OPERATIONS																	1,926,546	1,655,380	1,482,846
INTEREST EXPENSE—Net																	859,753	663,008	602,589
REFINANCING COSTS																	3,013	6,396	39,807
OTHER EXPENSE—Net																	915	419	3,020
EQUITY IN INCOME OF SUBSIDIARIES																	0	0	0
INCOME BEFORE INCOME TAXES																	1,062,865	985,557	837,430
INCOME TAX PROVISION (BENEFIT)																	221,986	24,021	208,889
Net income from continuing operations attributable to TD Group																	839,338	961,536	628,541
Net loss from discontinued operations																	50,432	(4,474)	(31,654)
Net income including noncontrolling interests																	891,311	957,062	596,887
NET INCOME ATTRIBUTABLE TO NONCONTROLLING INTERESTS																	(1,541)	0	0
INCOME FROM CONTINUING OPERATIONS INCLUDING NONCONTROLLING INTERESTS																	840,879	961,536	628,541
NET INCOME																	889,770	957,062	596,887
Statement of Comprehensive Income [Abstract]
Other comprehensive loss, net of tax																	(383,081)	89,243	64,644
TOTAL COMPREHENSIVE INCOME (LOSS)																	506,689	1,046,305	661,531
TransDigm Group
Condensed Income Statements, Captions [Line Items]
NET SALES	$ 1,541,320	[1],[2]	$ 1,521,061	[1],[2]	$ 1,167,520	[1],[2]	$ 993,302	[1],[2]	$ 1,049,434	[1],[2]	$ 980,662	[1],[2]	$ 933,070	[1],[2]	$ 847,960	[1],[2]	0	0	0
COST OF SALES																	0	0	0
GROSS PROFIT	882,082	[1],[2]	713,109	[1],[2]	649,964	[1],[2]	564,116	[1],[2]	597,266	[1],[2]	569,520	[1],[2]	534,074	[1],[2]	476,650	[1],[2]	0	0	0
SELLING AND ADMINISTRATIVE EXPENSES																	0	0	69
AMORTIZATION OF INTANGIBLE ASSETS																	0	0	0
(LOSS) INCOME FROM OPERATIONS																	0	0	(69)
INTEREST EXPENSE—Net																	0	0	0
REFINANCING COSTS																	0	0	0
OTHER EXPENSE—Net																	0	0	0
EQUITY IN INCOME OF SUBSIDIARIES																	(889,770)	(957,062)	(596,956)
INCOME BEFORE INCOME TAXES																	889,770	957,062	596,887
INCOME TAX PROVISION (BENEFIT)																	0	0	0
Net loss from discontinued operations	30,870		16,951		2,611		0		(1,531)		(145)		(5,562)		2,764		0	0	0
Net income including noncontrolling interests																	889,770	957,062	596,887
NET INCOME ATTRIBUTABLE TO NONCONTROLLING INTERESTS																	0	0	0
INCOME FROM CONTINUING OPERATIONS INCLUDING NONCONTROLLING INTERESTS	317,157		127,659		200,021		196,042		230,294		217,391		201,840		312,011		889,770	957,062	596,887
NET INCOME	$ 346,870	[1],[2]	$ 144,450	[1],[2]	$ 202,408	[1],[2]	$ 196,042	[1],[2]	$ 228,763	[1],[2]	$ 217,246	[1],[2]	$ 196,278	[1],[2]	$ 314,775	[1],[2]	889,770	957,062	596,887
Statement of Comprehensive Income [Abstract]
Other comprehensive loss, net of tax																	(383,081)	89,243	64,644
TOTAL COMPREHENSIVE INCOME (LOSS)																	506,689	1,046,305	661,531
TransDigm Inc.
Condensed Income Statements, Captions [Line Items]
NET SALES																	186,360	163,348	143,631
COST OF SALES																	109,414	94,387	79,403
GROSS PROFIT																	76,946	68,961	64,228
SELLING AND ADMINISTRATIVE EXPENSES																	258,465	110,405	99,558
AMORTIZATION OF INTANGIBLE ASSETS																	925	1,261	1,003
(LOSS) INCOME FROM OPERATIONS																	(182,444)	(42,705)	(36,333)
INTEREST EXPENSE—Net																	855,325	678,155	614,353
REFINANCING COSTS																	2,745	6,300	39,807
OTHER EXPENSE—Net																	(71,003)	(1,718)	(1,881)
EQUITY IN INCOME OF SUBSIDIARIES																	(1,866,584)	(1,306,511)	(1,318,945)
INCOME BEFORE INCOME TAXES																	897,073	581,069	630,333
INCOME TAX PROVISION (BENEFIT)																	0	(375,993)	33,377
Net loss from discontinued operations																	(7,303)	0	0
Net income including noncontrolling interests																	889,770	957,062	596,956
NET INCOME ATTRIBUTABLE TO NONCONTROLLING INTERESTS																	0	0	0
INCOME FROM CONTINUING OPERATIONS INCLUDING NONCONTROLLING INTERESTS																	897,073	957,062	596,956
NET INCOME																	889,770	957,062	596,956
Statement of Comprehensive Income [Abstract]
Other comprehensive loss, net of tax																	(278,353)	95,076	31,603
TOTAL COMPREHENSIVE INCOME (LOSS)																	611,417	1,052,138	628,559
TransDigm UK
Condensed Income Statements, Captions [Line Items]
NET SALES																	0	0	0
COST OF SALES																	0	0	0
GROSS PROFIT																	0	0	0
SELLING AND ADMINISTRATIVE EXPENSES																	14	0	0
AMORTIZATION OF INTANGIBLE ASSETS																	0	0	0
(LOSS) INCOME FROM OPERATIONS																	(14)	0	0
INTEREST EXPENSE—Net																	35,420	6,943	0
REFINANCING COSTS																	268	96	0
OTHER EXPENSE—Net																	89,539	0	0
EQUITY IN INCOME OF SUBSIDIARIES																	0	0	0
INCOME BEFORE INCOME TAXES																	(125,241)	(7,039)	0
INCOME TAX PROVISION (BENEFIT)																	0	0	0
Net loss from discontinued operations																	0	0	0
Net income including noncontrolling interests																	(125,241)	(7,039)	0
NET INCOME ATTRIBUTABLE TO NONCONTROLLING INTERESTS																	0	0	0
INCOME FROM CONTINUING OPERATIONS INCLUDING NONCONTROLLING INTERESTS																	(125,241)	(7,039)	0
NET INCOME																	(125,241)	(7,039)	0
Statement of Comprehensive Income [Abstract]
Other comprehensive loss, net of tax																	0	0	0
TOTAL COMPREHENSIVE INCOME (LOSS)																	(125,241)	(7,039)	0
Subsidiary Guarantors
Condensed Income Statements, Captions [Line Items]
NET SALES																	4,103,848	3,118,032	2,911,950
COST OF SALES																	1,771,217	1,253,018	1,191,770
GROSS PROFIT																	2,332,631	1,865,014	1,720,180
SELLING AND ADMINISTRATIVE EXPENSES																	348,928	425,736	277,083
AMORTIZATION OF INTANGIBLE ASSETS																	98,868	62,915	80,053
(LOSS) INCOME FROM OPERATIONS																	1,884,835	1,376,363	1,363,044
INTEREST EXPENSE—Net																	(11,638)	1,308	(1,248)
REFINANCING COSTS																	0	0	0
OTHER EXPENSE—Net																	(590,135)	(156,284)	7,736
EQUITY IN INCOME OF SUBSIDIARIES																	0	0	0
INCOME BEFORE INCOME TAXES																	2,486,608	1,531,339	1,356,556
INCOME TAX PROVISION (BENEFIT)																	187,331	379,665	156,251
Net loss from discontinued operations																	0	(2,427)	(9,496)
Net income including noncontrolling interests																	2,299,277	1,149,247	1,190,809
NET INCOME ATTRIBUTABLE TO NONCONTROLLING INTERESTS																	0	0	0
INCOME FROM CONTINUING OPERATIONS INCLUDING NONCONTROLLING INTERESTS																	2,299,277	1,151,674	1,200,305
NET INCOME																	2,299,277	1,149,247	1,190,809
Statement of Comprehensive Income [Abstract]
Other comprehensive loss, net of tax																	10,204	8,491	16,310
TOTAL COMPREHENSIVE INCOME (LOSS)																	2,309,481	1,157,738	1,207,119
Non-Guarantor Subsidiaries
Condensed Income Statements, Captions [Line Items]
NET SALES																	1,105,379	610,688	535,129
COST OF SALES																	705,685	367,153	333,985
GROSS PROFIT																	399,694	243,535	201,144
SELLING AND ADMINISTRATIVE EXPENSES																	140,366	(86,465)	35,845
AMORTIZATION OF INTANGIBLE ASSETS																	35,159	8,278	8,170
(LOSS) INCOME FROM OPERATIONS																	224,169	321,722	157,129
INTEREST EXPENSE—Net																	(19,354)	(23,398)	(10,516)
REFINANCING COSTS																	0	0	0
OTHER EXPENSE—Net																	572,514	158,421	(2,835)
EQUITY IN INCOME OF SUBSIDIARIES																	0	0	0
INCOME BEFORE INCOME TAXES																	(328,991)	186,699	170,480
INCOME TAX PROVISION (BENEFIT)																	34,655	20,349	19,261
Net loss from discontinued operations																	57,735	(2,047)	(22,158)
Net income including noncontrolling interests																	(305,911)	164,303	129,061
NET INCOME ATTRIBUTABLE TO NONCONTROLLING INTERESTS																	(1,541)	0	0
INCOME FROM CONTINUING OPERATIONS INCLUDING NONCONTROLLING INTERESTS																	(363,646)	166,350	151,219
NET INCOME																	(307,452)	164,303	129,061
Statement of Comprehensive Income [Abstract]
Other comprehensive loss, net of tax																	(147,493)	(17,837)	58,856
TOTAL COMPREHENSIVE INCOME (LOSS)																	(454,945)	146,466	187,917
Eliminations
Condensed Income Statements, Captions [Line Items]
NET SALES																	(172,384)	(80,942)	(86,424)
COST OF SALES																	(172,384)	(80,942)	(85,499)
GROSS PROFIT																	0	0	(925)
SELLING AND ADMINISTRATIVE EXPENSES																	0	0	0
AMORTIZATION OF INTANGIBLE ASSETS																	0	0	0
(LOSS) INCOME FROM OPERATIONS																	0	0	(925)
INTEREST EXPENSE—Net																	0	0	0
REFINANCING COSTS																	0	0	0
OTHER EXPENSE—Net																	0	0	0
EQUITY IN INCOME OF SUBSIDIARIES																	2,756,354	2,263,573	1,915,901
INCOME BEFORE INCOME TAXES																	(2,756,354)	(2,263,573)	(1,916,826)
INCOME TAX PROVISION (BENEFIT)																	0	0	0
Net loss from discontinued operations																	0	0	0
Net income including noncontrolling interests																	(2,756,354)	(2,263,573)	(1,916,826)
NET INCOME ATTRIBUTABLE TO NONCONTROLLING INTERESTS																	0	0	0
INCOME FROM CONTINUING OPERATIONS INCLUDING NONCONTROLLING INTERESTS																	(2,756,354)	(2,263,573)	(1,916,826)
NET INCOME																	(2,756,354)	(2,263,573)	(1,916,826)
Statement of Comprehensive Income [Abstract]
Other comprehensive loss, net of tax																	415,642	(85,730)	(106,769)
TOTAL COMPREHENSIVE INCOME (LOSS)																	$ (2,340,712)	$ (2,349,303)	$ (2,023,595)
[1]	Results adjusted to reflect amounts reclassified to discontinued operations due to the Company’s classification of Souriau-Sunbank and EIT at September 30, 2019, and Schroth at September 30, 2017, as discontinued operations. See Note 23, “Discontinued Operations,” for additional information.
[2]	The Company’s operating results include the results of operations of acquisitions from the effective date of each acquisition. See Note 2 “Acquisitions and Divestitures,” for additional details.

SUPPLEMENTAL GUARANTOR INFORM_6

SUPPLEMENTAL GUARANTOR INFORMATION - Supplemental Condensed Consolidating Statement of Cash Flows (Detail) - USD ($)	12 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2016
Condensed Cash Flow Statements, Captions [Line Items]
Net cash provided by operating activities	$ 1,015,472,000	$ 1,022,173,000	$ 788,733,000
Capital expenditures, net of disposals	(101,591,000)	(73,341,000)	(71,013,000)
Acquisition of business, net of cash acquired	(3,976,155,000)	(667,619,000)	(215,990,000)
Proceeds in connection with the sale of discontinued operations	188,766,000	57,383,000	0
Net cash used in investing activities	(3,888,980,000)	(683,577,000)	(287,003,000)
Intercompany activities	0	0	0
Proceeds from exercise of stock options	81,875,000	57,583,000	21,177,000
Special dividends and dividend equivalent payments	(1,712,219,000)	(56,148,000)	(2,581,552,000)
Treasury stock purchased	0	0	(389,821,000)
Proceeds from term loans, net	0	12,779,694,000	2,937,773,000
Repayments of Long-term Debt	(76,428,000)	(12,174,305,000)	(1,284,698,000)
Proceeds from senior secured notes due 2026, net	3,935,567,000	0	0
Cash tender and redemption of senior subordinated notes due 2020	(550,000,000)	0	0
Proceeds from senior subordinated notes, net	544,248,000	489,608,000	300,386,000
Cash tender and redemption of senior subordinated notes due 2021, including premium	0	0	(528,847,000)
Proceeds from trade receivable securitization facility, net	49,423,000	0	99,471,000
Financing fees and other	(1,113,000)	(10,832,000)	(17,571,000)
Net cash provided by (used in) financing activities	2,271,353,000	1,085,600,000	(1,443,682,000)
EFFECT OF EXCHANGE RATE CHANGES ON CASH AND CASH EQUIVALENTS	(3,376,000)	(1,740,000)	5,519,000
Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents, Period Increase (Decrease), Including Exchange Rate Effect	(605,531,000)
NET INCREASE (DECREASE) IN CASH AND CASH EQUIVALENTS	(605,531,000)	1,422,456,000	(936,433,000)
CASH AND CASH EQUIVALENTS, BEGINNING OF PERIOD	2,073,017,000	650,561,000	1,586,994,000
CASH AND CASH EQUIVALENTS, END OF PERIOD	1,467,486,000	2,073,017,000	650,561,000
Cash and Cash Equivalents	1,467,486,000	2,073,017,000	650,561,000	$ 1,586,994,000
Eliminations
Condensed Cash Flow Statements, Captions [Line Items]
Net cash provided by operating activities	10,832,000	2,174,000	475,000
Capital expenditures, net of disposals	0	0	0
Acquisition of business, net of cash acquired	0	0	0
Proceeds in connection with the sale of discontinued operations	0	0
Net cash used in investing activities	0	0	0
Intercompany activities	(10,832,000)	(2,174,000)	(475,000)
Proceeds from exercise of stock options	0	0	0
Special dividends and dividend equivalent payments	0	0	0
Treasury stock purchased			0
Proceeds from term loans, net		0	0
Repayments of Long-term Debt	0	0	0
Proceeds from senior secured notes due 2026, net	0
Cash tender and redemption of senior subordinated notes due 2020	0
Proceeds from senior subordinated notes, net	0	0	0
Cash tender and redemption of senior subordinated notes due 2021, including premium			0
Proceeds from trade receivable securitization facility, net	0		0
Financing fees and other	0	0	0
Net cash provided by (used in) financing activities	(10,832,000)	(2,174,000)	(475,000)
EFFECT OF EXCHANGE RATE CHANGES ON CASH AND CASH EQUIVALENTS	0	0	0
Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents, Period Increase (Decrease), Including Exchange Rate Effect	0
NET INCREASE (DECREASE) IN CASH AND CASH EQUIVALENTS		0	0
CASH AND CASH EQUIVALENTS, BEGINNING OF PERIOD	0	0	0
CASH AND CASH EQUIVALENTS, END OF PERIOD	0	0	0
Cash and Cash Equivalents	0	0	0
TransDigm UK
Condensed Cash Flow Statements, Captions [Line Items]
Net cash provided by operating activities	(249,794,000)	6,598,000	0
Capital expenditures, net of disposals	0	0	0
Acquisition of business, net of cash acquired	0	0	0
Proceeds in connection with the sale of discontinued operations	0	0
Net cash used in investing activities	0	0	0
Intercompany activities	250,986,000	(496,081,000)	0
Proceeds from exercise of stock options	0	0	0
Special dividends and dividend equivalent payments	0	0	0
Treasury stock purchased			0
Proceeds from term loans, net		0	0
Repayments of Long-term Debt	0	0	0
Proceeds from senior secured notes due 2026, net	0
Cash tender and redemption of senior subordinated notes due 2020	0
Proceeds from senior subordinated notes, net	0	489,608,000	0
Cash tender and redemption of senior subordinated notes due 2021, including premium			0
Proceeds from trade receivable securitization facility, net	0		0
Financing fees and other	(1,037,000)	0	0
Net cash provided by (used in) financing activities	249,949,000	(6,473,000)	0
EFFECT OF EXCHANGE RATE CHANGES ON CASH AND CASH EQUIVALENTS	0	0	0
Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents, Period Increase (Decrease), Including Exchange Rate Effect	155,000
NET INCREASE (DECREASE) IN CASH AND CASH EQUIVALENTS		125,000	0
CASH AND CASH EQUIVALENTS, BEGINNING OF PERIOD	125,000	0	0
CASH AND CASH EQUIVALENTS, END OF PERIOD	280,000	125,000	0
Cash and Cash Equivalents	280,000	125,000
TransDigm Group
Condensed Cash Flow Statements, Captions [Line Items]
Net cash provided by operating activities	0	0	(69,000)
Capital expenditures, net of disposals	0	0	0
Acquisition of business, net of cash acquired	0	0	0
Proceeds in connection with the sale of discontinued operations	0	0
Net cash used in investing activities	0	0	0
Intercompany activities	1,629,984,000	(3,462,000)	2,939,121,000
Proceeds from exercise of stock options	81,875,000	57,583,000	21,177,000
Special dividends and dividend equivalent payments	(1,712,219,000)	(56,148,000)	(2,581,552,000)
Treasury stock purchased			389,821,000
Proceeds from term loans, net		0	0
Repayments of Long-term Debt	0	0	0
Proceeds from senior secured notes due 2026, net	0
Cash tender and redemption of senior subordinated notes due 2020	0
Proceeds from senior subordinated notes, net	0	0	0
Cash tender and redemption of senior subordinated notes due 2021, including premium			0
Proceeds from trade receivable securitization facility, net	0		0
Financing fees and other	0	0	0
Net cash provided by (used in) financing activities	(360,000)	(2,027,000)	(11,075,000)
EFFECT OF EXCHANGE RATE CHANGES ON CASH AND CASH EQUIVALENTS	0	0	0
Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents, Period Increase (Decrease), Including Exchange Rate Effect	(360,000)
NET INCREASE (DECREASE) IN CASH AND CASH EQUIVALENTS		(2,027,000)	(11,144,000)
CASH AND CASH EQUIVALENTS, BEGINNING OF PERIOD	389,000	2,416,000	13,560,000
CASH AND CASH EQUIVALENTS, END OF PERIOD	29,000	389,000	2,416,000
Cash and Cash Equivalents	29,000	389,000	2,416,000
TransDigm Inc.
Condensed Cash Flow Statements, Captions [Line Items]
Net cash provided by operating activities	(868,208,000)	(386,152,000)	(587,800,000)
Capital expenditures, net of disposals	(3,608,000)	(2,001,000)	(1,984,000)
Acquisition of business, net of cash acquired	(3,923,850,000)	(667,619,000)	(215,990,000)
Proceeds in connection with the sale of discontinued operations	188,766,000	57,383,000
Net cash used in investing activities	(3,738,692,000)	(612,237,000)	(217,974,000)
Intercompany activities	21,960,000	1,785,796,000	(1,682,518,000)
Proceeds from exercise of stock options	0	0	0
Special dividends and dividend equivalent payments	0	0	0
Treasury stock purchased			0
Proceeds from term loans, net		12,779,694,000	2,937,773,000
Repayments of Long-term Debt	76,428,000	(12,174,305,000)	(1,284,698,000)
Proceeds from senior secured notes due 2026, net	3,935,567,000
Cash tender and redemption of senior subordinated notes due 2020	(550,000,000)
Proceeds from senior subordinated notes, net	544,248,000	0	300,386,000
Cash tender and redemption of senior subordinated notes due 2021, including premium			(528,847,000)
Proceeds from trade receivable securitization facility, net	0		99,471,000
Financing fees and other	2,325,000	(10,832,000)	(17,571,000)
Net cash provided by (used in) financing activities	3,877,672,000	2,380,353,000	(176,004,000)
EFFECT OF EXCHANGE RATE CHANGES ON CASH AND CASH EQUIVALENTS	0	0	0
Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents, Period Increase (Decrease), Including Exchange Rate Effect	(729,228,000)
NET INCREASE (DECREASE) IN CASH AND CASH EQUIVALENTS		1,381,964,000	(981,778,000)
CASH AND CASH EQUIVALENTS, BEGINNING OF PERIOD	1,821,437,000	439,473,000	1,421,251,000
CASH AND CASH EQUIVALENTS, END OF PERIOD	1,092,209,000	1,821,437,000	439,473,000
Cash and Cash Equivalents	1,092,209,000	1,821,437,000	439,473,000
Subsidiary Guarantors
Condensed Cash Flow Statements, Captions [Line Items]
Net cash provided by operating activities	2,449,925,000	1,216,263,000	1,334,099,000
Capital expenditures, net of disposals	(97,220,000)	(61,896,000)	(63,305,000)
Acquisition of business, net of cash acquired	(52,305,000)	0	0
Proceeds in connection with the sale of discontinued operations	0	0
Net cash used in investing activities	(149,525,000)	(61,896,000)	(63,305,000)
Intercompany activities	(2,310,900,000)	(1,155,927,000)	(1,279,805,000)
Proceeds from exercise of stock options	0	0	0
Special dividends and dividend equivalent payments	0	0	0
Treasury stock purchased			0
Proceeds from term loans, net		0	0
Repayments of Long-term Debt	0	0	0
Proceeds from senior secured notes due 2026, net	0
Cash tender and redemption of senior subordinated notes due 2020	0
Proceeds from senior subordinated notes, net	0	0	0
Cash tender and redemption of senior subordinated notes due 2021, including premium			0
Proceeds from trade receivable securitization facility, net	0		0
Financing fees and other	0	0	0
Net cash provided by (used in) financing activities	(2,310,900,000)	(1,155,927,000)	(1,279,805,000)
EFFECT OF EXCHANGE RATE CHANGES ON CASH AND CASH EQUIVALENTS	0	0	0
Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents, Period Increase (Decrease), Including Exchange Rate Effect	(10,500,000)
NET INCREASE (DECREASE) IN CASH AND CASH EQUIVALENTS		(1,560,000)	(9,011,000)
CASH AND CASH EQUIVALENTS, BEGINNING OF PERIOD	(1,763,000)	(203,000)	8,808,000
CASH AND CASH EQUIVALENTS, END OF PERIOD	(12,263,000)	(1,763,000)	(203,000)
Cash and Cash Equivalents	(12,263,000)	(1,763,000)	(203,000)
Non-Guarantor Subsidiaries
Condensed Cash Flow Statements, Captions [Line Items]
Net cash provided by operating activities	(327,283,000)	183,290,000	42,028,000
Capital expenditures, net of disposals	(763,000)	(9,444,000)	(5,724,000)
Acquisition of business, net of cash acquired	0	0	0
Proceeds in connection with the sale of discontinued operations	0	0
Net cash used in investing activities	(763,000)	(9,444,000)	(5,724,000)
Intercompany activities	418,802,000	(128,152,000)	23,677,000
Proceeds from exercise of stock options	0	0	0
Special dividends and dividend equivalent payments	0	0	0
Treasury stock purchased			0
Proceeds from term loans, net		0	0
Repayments of Long-term Debt	0	0	0
Proceeds from senior secured notes due 2026, net	0
Cash tender and redemption of senior subordinated notes due 2020	0
Proceeds from senior subordinated notes, net	0	0	0
Cash tender and redemption of senior subordinated notes due 2021, including premium			0
Proceeds from trade receivable securitization facility, net	49,423,000		0
Financing fees and other	(2,401,000)	0	0
Net cash provided by (used in) financing activities	465,824,000	(128,152,000)	23,677,000
EFFECT OF EXCHANGE RATE CHANGES ON CASH AND CASH EQUIVALENTS	(3,376,000)	(1,740,000)	5,519,000
Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents, Period Increase (Decrease), Including Exchange Rate Effect	134,402,000
NET INCREASE (DECREASE) IN CASH AND CASH EQUIVALENTS		43,954,000	65,500,000
CASH AND CASH EQUIVALENTS, BEGINNING OF PERIOD	252,829,000	208,875,000	143,375,000
CASH AND CASH EQUIVALENTS, END OF PERIOD	387,231,000	252,829,000	208,875,000
Cash and Cash Equivalents	$ 387,231,000	$ 252,829,000	$ 208,875,000

Valuation and Qualifying Acco_2

Valuation and Qualifying Accounts (Detail) - USD ($) $ in Thousands		12 Months Ended
		Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2017
Allowance for Doubtful Accounts
SEC Schedule, 12-09, Valuation and Qualifying Accounts Disclosure [Line Items]
Balance at Beginning of Period		$ 4,674	$ 3,819	$ 4,414
Charged to Costs and Expenses		(5,377)	(1,498)	1,095
Acquisitions		9,417	989	363
Deductions from Reserve	[1]	(2,066)	(1,632)	(2,053)
Balance at End of Period		17,402	4,674	3,819
SEC Schedule 12-09, Inventory Reserve [Member]
SEC Schedule, 12-09, Valuation and Qualifying Accounts Disclosure [Line Items]
Balance at Beginning of Period		94,498
Balance at End of Period			94,498
Reserve for excess and obsolete inventory
SEC Schedule, 12-09, Valuation and Qualifying Accounts Disclosure [Line Items]
Balance at Beginning of Period		99,351	79,775	80,039
Charged to Costs and Expenses		(17,148)	(14,998)	(17,361)
Acquisitions		16,980	10,764	4,254
Deductions from Reserve	[1]	(9,676)	(11,039)	(21,879)
Balance at End of Period		123,803	99,351	79,775
Valuation Allowance of Deferred Tax Assets
SEC Schedule, 12-09, Valuation and Qualifying Accounts Disclosure [Line Items]
Balance at Beginning of Period		47,249	33,214	27,286
Charged to Costs and Expenses		(39,651)	(14,035)	5,928
Acquisitions		30,760	0	0
Deductions from Reserve	[1]	0	0	0
Balance at End of Period		$ 117,660	$ 47,249	$ 33,214
[1]	The amounts in this column represent charge-offs net of recoveries and the impact of foreign currency translation adjustments.