CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	6 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Cash flows from operating activities
Net income	$ 83,506	$ 27,876
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	17,634	13,730
Gain on settlement of equity method investment		(1,847)
Stock-based compensation	10,129	6,884
Amortization of premium on marketable securities and deferred financing costs	217	28
Earnings of equity method investments	(3,602)	(4,719)
Loss recovery on insurance claim	(1,103)
Deferred income tax benefit	(49,156)	334
Other gains on disposals of assets		(117)
Changes in operating assets and liabilities, net of acquisitions:
Accounts receivable	(16,949)	(9,672)
Inventories	(16,233)	(7,341)
Prepaid expenses and other current assets	(17,248)	(2,256)
Accounts payable	14,899	10,072
Deferred revenue	(2,783)	14,425
Accrued warranty and retrofit costs	(16)	792
Accrued compensation and tax withholdings	(4,151)	(1,799)
Accrued restructuring costs	(1,336)	(3,799)
Accrued expenses and other current liabilities	9,619	707
Net cash provided by operating activities	23,427	43,298
Cash flows from investing activities
Purchases of property, plant and equipment	(5,675)	(5,153)
Purchases of marketable securities	(49,560)
Sales and maturities of marketable securities	100
Acquisitions, net of cash acquired	(64,988)	(5,346)
Purchases of other investments		(170)
Proceeds from sales of property, plant and equipment	200
Net cash used in investing activities	(119,923)	(10,669)
Cash flows from financing activities
Proceeds from term loan	197,554
Proceeds from issuance of common stock	1,395	960
Payment of deferred financing costs	(318)	(27)
Repayment of term loan	(500)
Common stock dividends paid	(14,125)	(13,945)
Net cash provided by (used in) financing activities	184,006	(13,012)
Effects of exchange rate changes on cash and cash equivalents	4,884	(764)
Net increase in cash and cash equivalents	92,394	18,853
Cash and cash equivalents, beginning of period	101,622	85,086
Cash and cash equivalents, end of period	194,016	103,939
Supplemental disclosure of non-cash investing and financing activities:
Purchases of property, plant and equipment included in accounts payable	$ 716	543
Fair value of non-cash consideration for the acquisition of Cool Lab, LLC		$ 10,348