CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	12 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2019
Cash flows from operating activities
Net income	$ 110,747	$ 64,853	$ 437,416
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	65,333	65,496	54,454
Impairment of intangible assets	13,364		285
Stock-based compensation	27,456	16,317	20,113
Amortization of premium on marketable securities and deferred financing costs	225	233	1,121
Earnings of equity method investments			(6,188)
Deferred income taxes	(17,265)	(5,407)	(15,161)
Loss on extinguishment of debt			14,339
Other losses on disposals of assets	260	226	209
Adjustment to the gain on divestiture, net of tax / Gain on divestiture, net of tax	948	319	(408,575)
Contingent transaction fees paid stemming from divestiture			(13,388)
Taxes paid stemming from divestiture		(91,500)
Changes in operating assets and liabilities, net of acquisitions and divestiture:
Accounts receivable	(69,643)	(18,755)	(11,445)
Inventories	(50,443)	(13,144)	(2,933)
Prepaid expenses and other assets	(15,968)	25,642	(16,009)
Accounts payable	30,967	792	4,695
Deferred revenue	(3,939)	(139)	4,213
Accrued warranty and retrofit costs	54	760	1,109
Accrued compensation and tax withholdings	7,298	11,097	(6,453)
Accrued restructuring costs	124	(865)	399
Proceeds from recovery on insurance claim			1,082
Accrued expenses and other liabilities	50,339	(18,059)	31,615
Net cash provided by (used in) operating activities	149,857	37,866	90,898
Cash flows from investing activities
Purchases of property, plant and equipment	(52,805)	(39,924)	(23,861)
Purchases of marketable securities	(151)	(10,894)	(35,225)
Sales of marketable securities	25	2,492	48,903
Maturities of marketable securities	96	42,328	2,557
Proceeds from divestiture			661,642
Adjustment to proceeds from divestiture	(1,802)
Acquisitions, net of cash acquired	(93,712)	(15,744)	(442,704)
Settlement (issuance) of note receivables	2,000	(1,000)
Net cash (used in) provided by investing activities	(146,349)	(22,742)	211,312
Cash flows from financing activities
Proceeds from term loans, net of discount			686,386
Proceeds from issuance of common stock	5,812	4,595	3,422
Payments of financing costs			(687)
Principal payments on debt	(828)	(828)	(850,190)
Payments of finance leases	(1,164)	(1,277)	(1,197)
Common stock dividends paid	(29,726)	(29,513)	(28,895)
Net cash used in financing activities	(25,906)	(27,023)	(191,161)
Effects of exchange rate changes on cash and cash equivalents	5,205	9,254	(3,586)
Net decrease in cash, cash equivalents and restricted cash	(17,193)	(2,645)	107,463
Cash, cash equivalents and restricted cash, beginning of period	302,526	305,171	197,708
Cash, cash equivalents and restricted cash, end of period	285,333	302,526	305,171
Supplemental disclosures:
Cash paid for interest	1,435	2,159	20,799
Cash paid for income taxes, net	$ 38,020	$ 102,010	$ 16,990