Consolidated Statements of Cash Flows (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2012
Cash flows from operating activities:
Net income	$ 36,911	$ 69,557	$ 35,118
Adjustments to reconcile net income to net cash provided by (used in) operating activities:
Deferred income tax expense (benefit)	818	(523)	808
Depreciation and amortization	17,774	12,229	9,587
Accretion of discounts on short-term-investments	49	162	208
Stock-based compensation expense	4,119	544	762
Bad debt expense	833	457	118
Inventory obsolescence expense	2,617	187	1,793
Gross profit from sale of used rental equipment	(9,031)	(13,627)	(9,992)
(Gain) loss on disposal of property, plant and equipment	(64)	301	(34)
Realized (gain) loss on short-term investments	0	(19)	1
Effects of changes in operating assets and liabilities:
Trade accounts and notes receivable	25,605	(33,717)	3,781
Inventories	(10,452)	(73,357)	(15,630)
Costs and estimated earnings in excess of billings	12,400	(12,400)
Prepaid expenses and other current assets	(1,641)	(458)	(293)
Prepaid income taxes	353	(722)	(4,500)
Accounts payable trade	(11,756)	(442)	12,151
Accrued expenses and other	(3,435)	3,324	576
Deferred revenue	2,685	(7,541)	7,897
Income taxes payable	(135)	(1,116)	873
Net cash provided by (used in) operating activities	67,650	(57,161)	43,224
Cash flows from investing activities:
Purchase of property, plant and equipment	(6,792)	(19,384)	(4,013)
Proceeds from the sale of property, plant and equipment	27		17
Investment in rental equipment	(26,719)	(22,275)	(31,716)
Proceeds from the sale of used rental equipment	16,390	25,497	24,184
Purchases of short-term investments	(21,610)	(1,587)	(16,823)
Proceeds from the sale of short-term investments	2,000	21,139	2,030
Net cash provided by (used in) investing activities	(36,704)	3,390	(26,321)
Cash flows from financing activities:
Net (payments) borrowings under line of credit	(931)	931
Excess tax benefits from stock-based compensation	178	3,390	1,131
Proceeds from exercise of stock options and other	424	1,419	1,358
Net cash provided by (used in) financing activities	(329)	5,740	2,489
Effect of exchange rate changes on cash	14	5	(28)
Increase (decrease) in cash and cash equivalents	30,631	(48,026)	19,364
Cash and cash equivalents, beginning of fiscal year	2,726	50,752	31,388
Cash and cash equivalents, end of fiscal year	$ 33,357	$ 2,726	$ 50,752