Condensed Consolidating Financial Information (Details 4) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2013	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2013
Cash flows from operating activities:
Net income (loss)	$ 126,774	$ 23,008	$ (25,198)	$ 7,084	$ 16,681	$ 10,893	$ (10,082)	$ (1,434)	$ 131,668	$ 16,058	$ 7,137
Adjustments to reconcile net income (loss) to net cash provided by (used in) operating activities:
Depreciation and amortization									53,973	55,134	52,317
Interest expense related to amortization of debt issue costs and debt discount									6,180	2,175	5,841
Stock-based compensation									2,826	2,165	1,703
Deferred income taxes									(96,742)	1,666	698
Tax benefit from exercise of stock appreciation rights and vesting of restricted stock									(1,543)	0	0
Net loss (gain) on disposition of property, plant and equipment									49	95	(649)
Loss (gain) on sale of discontinued operations, net of income taxes									229	(2,727)	55
Asset impairments									0	1,815	0
Net loss of unconsolidated joint ventures									262	529	0
Equity in earnings of subsidiaries									0	0	0
Decrease (increase) in trade receivables									(14,194)	517	(5,035)
Decrease (increase) in inventories									(1,007)	(2,347)	2,221
Increase (decrease) in accounts payable and accrued liabilities									(11,557)	(13,225)	(4,218)
Other changes in operating assets and liabilities, net									(6,756)	(1,478)	(1,507)
Net cash provided by operating activities									63,388	60,377	58,563
Cash flows from investing activities:
Business acquisitions									(5,650)	(95,604)	(43,250)
Investments in unconsolidated joint ventures									(125)	(1,875)	0
Purchase of property, plant and equipment									(36,859)	(35,799)	(29,119)
Proceeds from disposition of property, plant and equipment									915	905	791
Proceeds from sale of discontinued operations									0	4,666	4,813
Net decrease (increase) in long-term receivables and deposits									3,450	7,445	(1,171)
Net change in other assets									(597)	(1,556)	(437)
Net cash used in investing activities									(38,866)	(121,818)	(68,373)
Cash flows from financing activities:
Net proceeds from issuance of long-term debt									414,675	146,650	0
Net proceeds from issuance of common stock									0	0	77,957
Payments on long-term debt									(449,799)	(7,792)	(47,355)
Dividends paid to non-controlling interest in consolidated subsidiary									(1,690)	(950)	0
Employee stock purchases									804	759	742
Tax benefit from exercise of stock appreciation rights and vesting of restricted stock									1,543	0	0
Intercompany transfers									0	0	0
Net cash provided by (used in) financing activities									(34,467)	138,667	31,344
Net increase (decrease) in cash and cash equivalents									(9,945)	77,226	21,534
Cash and cash equivalents, beginning of period				152,542				75,316	152,542	75,316	53,782
Cash and cash equivalents, end of period	142,597				152,542				142,597	152,542	75,316
Consolidation, Eliminations
Cash flows from operating activities:
Net income (loss)									(54,350)	(62,719)	(47,117)
Adjustments to reconcile net income (loss) to net cash provided by (used in) operating activities:
Equity in earnings of subsidiaries									54,350	62,719	47,117
Guarantor Subsidiaries | Reportable Legal Entities
Cash flows from operating activities:
Net income (loss)									52,799	60,141	47,117
Adjustments to reconcile net income (loss) to net cash provided by (used in) operating activities:
Depreciation and amortization									50,538	52,716	52,027
Stock-based compensation									1,014	843	765
Deferred income taxes									7,850	1,062	698
Net loss (gain) on disposition of property, plant and equipment									(70)	44	(649)
Loss (gain) on sale of discontinued operations, net of income taxes									45	(2,727)	55
Asset impairments										1,815
Decrease (increase) in trade receivables									(14,295)	(90)	(5,035)
Decrease (increase) in inventories									(783)	(3,927)	2,221
Increase (decrease) in accounts payable and accrued liabilities									(2,147)	(17,364)	(5,637)
Other changes in operating assets and liabilities, net									41,907	33,349	31,000
Net cash provided by operating activities									136,858	125,862	122,562
Cash flows from investing activities:
Business acquisitions									(5,650)	(10,500)	(43,250)
Investments in unconsolidated joint ventures									(125)
Purchase of property, plant and equipment									(30,972)	(30,672)	(26,940)
Proceeds from disposition of property, plant and equipment									906	905	791
Proceeds from sale of discontinued operations										4,666	4,813
Net decrease (increase) in long-term receivables and deposits									2,382	7,145	(1,890)
Net change in other assets									(718)	(2,275)	(294)
Net cash used in investing activities									(34,177)	(30,731)	(66,770)
Cash flows from financing activities:
Employee stock purchases									583	580	539
Intercompany transfers									(110,997)	(132,872)	(29,695)
Net cash provided by (used in) financing activities									(110,414)	(132,292)	(29,156)
Net increase (decrease) in cash and cash equivalents									(7,733)	(37,161)	26,636
Cash and cash equivalents, beginning of period				33,552				70,747	33,552	70,747	44,111
Cash and cash equivalents, beginning of period								70,713		70,713
Cash and cash equivalents, end of period	25,819				33,552				25,819	33,552	70,747
Cash and cash equivalents, end of period											70,713
Non-Guarantor Subsidiaries | Reportable Legal Entities
Cash flows from operating activities:
Net income (loss)									2,420	3,352
Adjustments to reconcile net income (loss) to net cash provided by (used in) operating activities:
Depreciation and amortization									2,922	2,146
Deferred income taxes									(25,808)	604
Tax benefit from exercise of stock appreciation rights and vesting of restricted stock									(965)
Net loss (gain) on disposition of property, plant and equipment									119	6
Loss (gain) on sale of discontinued operations, net of income taxes									184
Net loss of unconsolidated joint ventures									262	529
Decrease (increase) in trade receivables									101	607
Decrease (increase) in inventories									(224)	1,580
Increase (decrease) in accounts payable and accrued liabilities									3,519	828
Other changes in operating assets and liabilities, net									17,832	129
Net cash provided by operating activities									362	9,781
Cash flows from investing activities:
Investments in unconsolidated joint ventures										(1,875)
Purchase of property, plant and equipment									(662)	(829)
Proceeds from disposition of property, plant and equipment									9
Net cash used in investing activities									(653)	(2,704)
Cash flows from financing activities:
Dividends paid to non-controlling interest in consolidated subsidiary									(1,690)	(950)
Employee stock purchases									45
Tax benefit from exercise of stock appreciation rights and vesting of restricted stock									965
Intercompany transfers									(1,216)	(397)
Net cash provided by (used in) financing activities									(1,896)	(1,347)
Net increase (decrease) in cash and cash equivalents									(2,187)	5,730
Cash and cash equivalents, beginning of period				5,764				34	5,764	34
Cash and cash equivalents, end of period	3,577				5,764				3,577	5,764	34
Parent Company | Reportable Legal Entities
Cash flows from operating activities:
Net income (loss)									130,799	15,284	7,137
Adjustments to reconcile net income (loss) to net cash provided by (used in) operating activities:
Depreciation and amortization									513	272	290
Interest expense related to amortization of debt issue costs and debt discount									6,180	2,175	5,841
Stock-based compensation									1,812	1,322	938
Deferred income taxes									(78,784)
Tax benefit from exercise of stock appreciation rights and vesting of restricted stock									(578)
Net loss (gain) on disposition of property, plant and equipment										45
Equity in earnings of subsidiaries									(54,350)	(62,719)	(47,117)
Increase (decrease) in accounts payable and accrued liabilities									(12,929)	3,311	1,419
Other changes in operating assets and liabilities, net									(66,495)	(34,956)	(32,507)
Net cash provided by operating activities									(73,832)	(75,266)	(63,999)
Cash flows from investing activities:
Business acquisitions										(85,104)
Purchase of property, plant and equipment									(5,225)	(4,298)	(2,179)
Net decrease (increase) in long-term receivables and deposits									1,068	300	719
Net change in other assets									121	719	(143)
Net cash used in investing activities									(4,036)	(88,383)	(1,603)
Cash flows from financing activities:
Net proceeds from issuance of long-term debt									414,675	146,650
Net proceeds from issuance of common stock											77,957
Payments on long-term debt									(449,799)	(7,792)	(47,355)
Employee stock purchases									176	179	203
Tax benefit from exercise of stock appreciation rights and vesting of restricted stock									578
Intercompany transfers									112,213	133,269	29,695
Net cash provided by (used in) financing activities									77,843	272,306	60,500
Net increase (decrease) in cash and cash equivalents									(25)	108,657	(5,102)
Cash and cash equivalents, beginning of period				$ 113,226				$ 4,569	113,226	4,569	9,671
Cash and cash equivalents, end of period	$ 113,201				$ 113,226				$ 113,201	$ 113,226	$ 4,569