CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	12 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2017
Cash flows from operating activities
Net income	$ 437,416	$ 116,464	$ 62,612
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	54,454	37,429	28,149
Gain on settlement of equity method investment			(1,847)
Impairment of property, plant and equipment	285
Stock-based compensation	20,113	19,822	17,278
Amortization of premium on marketable securities and deferred financing costs	1,121	710	252
Earnings of equity method investments	(6,188)	(6,788)	(9,381)
Loss recovery on insurance claim		(1,103)
Deferred income taxes	(15,161)	(45,217)	517
Loss on extinguishment of debt	14,339
Pension settlement			(259)
Other losses (gains) on disposals of assets	209	(758)	(406)
Gain on sale of divestiture, net of tax	(408,575)
Contingent transaction fees paid stemming from divestiture	(13,388)
Changes in operating assets and liabilities, net of acquisitions and divestiture:
Accounts receivable	(11,445)	(28,463)	(11,178)
Inventories	(2,933)	(24,365)	(12,792)
Prepaid expenses and other assets	(16,009)	(3,676)	(5,829)
Accounts payable	4,695	5,457	7,846
Deferred revenue	4,213	2,791	8,049
Accrued warranty and retrofit costs	1,109	(157)	1,602
Accrued compensation and tax withholdings	(6,453)	5,978	5,565
Accrued restructuring costs	399	(1,080)	(4,241)
Accrued pension costs			(32)
Proceeds from recovery on insurance claim	1,082
Accrued expenses and other liabilities	31,615	(3,080)	10,319
Net cash provided by operating activities	90,898	73,964	96,224
Cash flows from investing activities
Purchases of property, plant and equipment	(23,861)	(12,787)	(12,677)
Purchases of technology intangibles			(240)
Purchases of marketable securities	(35,225)	(69,692)
Sales of marketable securities	48,903	1,584	3,590
Maturities of marketable securities	2,557	17,482
Proceeds from divestiture	661,642
Acquisitions, net of cash acquired	(442,704)	(85,755)	(44,791)
Purchase of other investments		(500)	(170)
Proceeds from sales of property, plant and equipment		200	100
Net cash provided by (used in) investing activities	211,312	(148,468)	(54,188)
Cash flows from financing activities
Proceeds from term loans, net of discount	686,386	197,554
Proceeds from issuance of common stock	3,422	2,826	2,040
Payments of financing costs	(687)	(318)	(28)
Principal payments on debt	(850,190)	(1,500)
Payments of capital leases	(1,197)
Common stock dividends paid	(28,895)	(28,285)	(27,932)
Net cash provided by (used in) financing activities	(191,161)	170,277	(25,920)
Effects of exchange rate changes on cash and cash equivalents	(3,586)	313	420
Net increase in cash, cash equivalents and restricted cash	107,463	96,086	16,536
Cash, cash equivalents and restricted cash, beginning of period	197,708	101,622	85,086
Cash, cash equivalents and restricted cash, end of period	305,171	197,708	101,622
Supplemental disclosures:
Cash paid for interest	20,799	6,537	200
Cash paid for income taxes, net	$ 16,990	$ 21,051	8,142
Supplemental disclosure of non-cash investing and financing activities:
Deferred financing costs included in accounts payable			423
Fair value of non-cash consideration for the acquisition of Cool Lab, LLC			$ 10,348