CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	3 Months Ended		6 Months Ended		12 Months Ended
	Mar. 31, 2017	Mar. 31, 2016	Mar. 31, 2017	Mar. 31, 2016	Sep. 30, 2016
Cash flows from operating activities:
Net income	$ 5,132	$ 2,384	$ 11,960	$ 15,105
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	18,365	14,115	36,207	27,897
Interest expense related to amortization of debt issue costs and debt discount	700	600	1,606	1,184
Debt pre-payment premiums			0	93
Stock-based compensation	400	800	901	1,521
Deferred income taxes			7,099	8,643
Tax benefit from exercise of stock appreciation rights and vesting of restricted stock			(5,860)	(97)
Net gain on disposition of property, plant and equipment			(216)	(46)
Net loss of unconsolidated joint venture			19	26
Decrease in trade receivables			19,682	33,538
Increase in inventories			(14,958)	(4,066)
Decrease in accounts payable and accrued liabilities			(19,413)	(36,372)
Other changes in operating assets and liabilities, net			(2,357)	(2,985)
Net cash provided by (used in) operating activities			34,670	44,441
Cash flows from investing activities:
Business acquisitions, net of cash acquired			(10,530)	(96,457)
Purchase of property, plant and equipment	(14,193)	(13,197)	(29,733)	(20,882)
Proceeds from disposition of property, plant and equipment			626	404
Net decrease (increase) in long-term receivables and deposits			4,890	(1,729)
Net change in other assets			2,368	(3,817)
Net cash provided by (used in) investing activities			(32,379)	(122,481)
Cash flows from financing activities:
Payments on long-term debt			(15,000)	(5,874)
Debt pre-payment premiums			0	(93)
Dividends paid to non-controlling interest in consolidated subsidiary			(657)	(735)
Employee stock purchases			336	539
Tax benefit from exercise of stock appreciation rights and vesting of restricted stock			5,860	97
Net cash provided by (used in) financing activities			(9,461)	(6,066)
Net increase (decrease) in cash and cash equivalents			(7,170)	(84,106)
Cash and cash equivalents, beginning of period			65,298	142,597	$ 142,597
Cash and cash equivalents, end of period	$ 58,128	$ 58,491	$ 58,128	$ 58,491	$ 65,298