CONSOLIDATED STATEMENTS OF CASH FLOWS (unaudited) - USD ($) $ in Thousands	9 Months Ended
	Jun. 30, 2017	Jun. 30, 2016
Cash flows from operating activities
Net income (loss)	$ 45,226	$ (80,022)
Adjustments to reconcile net income (loss) to net cash provided by operating activities:
Depreciation and amortization	20,649	21,320
Gain on settlement of equity method investment	(1,847)
Stock-based compensation	11,081	8,206
Amortization of premium on marketable securities and deferred financing costs	24	368
Undistributed earnings of equity method investments	(7,249)	(1,248)
Deferred income tax provision	498	71,875
Gain on disposal of long-lived assets	(106)
Changes in operating assets and liabilities, net of acquisitions:
Accounts receivable	(14,644)	2,862
Inventories	(12,851)	2,110
Prepaid expenses and other current assets	(6,076)	(3,909)
Accounts payable	9,470	(4,689)
Deferred revenue	17,875	7,171
Accrued warranty and retrofit costs	1,299	(87)
Accrued compensation and tax withholdings	279	(6,558)
Accrued restructuring costs	(4,201)	3,720
Accrued expenses and other current liabilities	1,954	(5,010)
Net cash provided by operating activities	61,381	16,109
Cash flows from investing activities
Purchases of property, plant and equipment	(6,827)	(9,414)
Purchases of technology intangibles	(240)
Purchases of marketable securities		(12,901)
Sales and maturities of marketable securities	3,590	139,388
Disbursement for a loan receivable		(1,491)
Acquisitions, net of cash acquired	(5,346)	(125,498)
Purchases of other investments	(170)	(500)
Net cash used in investing activities	(8,993)	(10,416)
Cash flows from financing activities
Proceeds from issuance of common stock	960	948
Payment of deferred financing costs	(27)	(508)
Common stock dividends paid	(20,932)	(20,613)
Net cash used in financing activities	(19,999)	(20,173)
Effects of exchange rate changes on cash and cash equivalents	(394)	(126)
Net increase (decrease) in cash and cash equivalents	31,995	(14,606)
Cash and cash equivalents, beginning of period	85,086	80,722
Cash and cash equivalents, end of period	117,081	66,116
Supplemental disclosure of non-cash investing and financing activities:
Purchases of property, plant and equipment included in accounts payable	1,009	$ 1,245
Fair value of non-cash consideration for the acquisition of Cool Lab, LLC	$ 10,348