Condensed Consolidating Financial Information - Balance Sheets (Details) - USD ($) $ in Thousands	Mar. 31, 2017	Sep. 30, 2016	Mar. 31, 2016	Sep. 30, 2015
Current assets:
Cash and cash equivalents	$ 58,128	$ 65,298	$ 58,491	$ 142,597
Trade receivables, net	133,725	152,084
Inventories	89,997	72,668
Current income taxes	2,681	1,187
Other	10,076	13,517
Total current assets	294,607	304,754
Property, plant and equipment, net	218,399	206,792
Other assets:
Goodwill	300,265	290,503
Intangible assets, net	306,304	319,162
Deferred income taxes	66,532	68,059
Other	43,530	49,173
Total other assets	716,631	726,897
Total assets	1,229,637	1,238,443	1,238,443
Current liabilities:
Accounts payable	28,159	30,211
Accrued personnel costs	38,886	45,366
Other accrued liabilities	55,584	63,785
Current portion of long-term debt		7,785
Total current liabilities	122,629	147,147
Long-term liabilities:
Long-term debt, net	741,048	746,716
Other	44,498	41,230
Total long-term liabilities	785,546	787,946
Total liabilities	908,175	935,093
Redeemable non-controlling interest in consolidated subsidiary	13,458	13,363
Stockholders' equity:
Common stock	75	74
Capital in excess of par value	739,905	733,117
Retained earnings (accumulated deficit)	(430,585)	(441,793)
Treasury stock	(1,391)	(1,411)
Total stockholders' equity	308,004	289,987
Total liabilities and stockholders' equity	1,229,637	1,238,443
Consolidation, Eliminations
Current assets:
Current income taxes	(66,408)	(58,802)
Total current assets	(66,408)	(58,802)
Other assets:
Investments in subsidiaries	(827,541)	(721,760)
Intercompany accounts and notes	(719,052)	(727,747)
Deferred income taxes	(14,385)	(12,077)
Total other assets	(1,560,978)	(1,461,584)
Total assets	(1,627,386)	(1,520,386)
Current liabilities:
Current income taxes	(66,408)	(58,802)
Total current liabilities	(66,408)	(58,802)
Long-term liabilities:
Deferred income taxes		(12,077)
Intercompany accounts and notes	(719,052)	(727,747)
Other	(14,385)
Total long-term liabilities	(733,437)	(739,824)
Total liabilities	(799,845)	(798,626)
Stockholders' equity:
Capital in excess of par value	(836,647)	(764,359)
Retained earnings (accumulated deficit)	9,106	42,599
Total stockholders' equity	(827,541)	(721,760)
Total liabilities and stockholders' equity	(1,627,386)	(1,520,386)
Guarantor Subsidiaries
Current assets:
Cash and cash equivalents	29,344	27,012	15,989	25,819
Trade receivables, net	127,396	145,443
Inventories	84,506	67,549
Other	8,814	11,975
Total current assets	250,060	251,979
Property, plant and equipment, net	200,191	179,758
Other assets:
Goodwill	256,611	248,016
Intangible assets, net	270,779	282,239
Intercompany accounts and notes	116,699	26,707
Other	10,177	13,293
Total other assets	654,266	570,255
Total assets	1,104,517	1,001,992
Current liabilities:
Accounts payable	26,528	27,659
Accrued personnel costs	9,950	14,945
Current income taxes	63,019	56,553
Other accrued liabilities	48,764	55,942
Total current liabilities	148,261	155,099
Long-term liabilities:
Deferred income taxes		12,077
Other	19,501	4,581
Total long-term liabilities	19,501	16,658
Total liabilities	167,762	171,757
Stockholders' equity:
Capital in excess of par value	786,669	711,755
Retained earnings (accumulated deficit)	150,086	118,480
Total stockholders' equity	936,755	830,235
Total liabilities and stockholders' equity	1,104,517	1,001,992
Non-Guarantor Subsidiaries
Current assets:
Cash and cash equivalents	8,783	5,304	3,192	3,577
Trade receivables, net	6,329	6,641
Inventories	5,491	5,119
Other	613	1,481
Total current assets	21,216	18,545
Property, plant and equipment, net	9,761	9,852
Other assets:
Goodwill	43,654	42,487
Intangible assets, net	35,525	36,923
Deferred income taxes	22,618	23,083
Other	8,842	10,922
Total other assets	110,639	113,415
Total assets	141,616	141,812
Current liabilities:
Accounts payable	1,157	1,301
Accrued personnel costs	371	519
Current income taxes	3,389	2,249
Other accrued liabilities	3,328	5,002
Total current liabilities	8,245	9,071
Long-term liabilities:
Intercompany accounts and notes	212,343	211,087
Other	16,960	16,941
Total long-term liabilities	229,303	228,028
Total liabilities	237,548	237,099
Redeemable non-controlling interest in consolidated subsidiary	13,458	13,363
Stockholders' equity:
Capital in excess of par value	49,802	52,429
Retained earnings (accumulated deficit)	(159,192)	(161,079)
Total stockholders' equity	(109,390)	(108,650)
Total liabilities and stockholders' equity	141,616	141,812
Parent
Current assets:
Cash and cash equivalents	20,001	32,982	$ 39,310	$ 113,201
Current income taxes	69,089	59,989
Other	649	61
Total current assets	89,739	93,032
Property, plant and equipment, net	8,447	17,182
Other assets:
Investments in subsidiaries	827,541	721,760
Intercompany accounts and notes	602,353	701,040
Deferred income taxes	58,299	57,053
Other	24,511	24,958
Total other assets	1,512,704	1,504,811
Total assets	1,610,890	1,615,025
Current liabilities:
Accounts payable	474	1,251
Accrued personnel costs	28,565	29,902
Other accrued liabilities	3,492	2,841
Current portion of long-term debt		7,785
Total current liabilities	32,531	41,779
Long-term liabilities:
Long-term debt, net	741,048	746,716
Intercompany accounts and notes	506,709	516,660
Other	22,422	19,708
Total long-term liabilities	1,270,179	1,283,084
Total liabilities	1,302,710	1,324,863
Stockholders' equity:
Common stock	75	74
Capital in excess of par value	740,081	733,292
Retained earnings (accumulated deficit)	(430,585)	(441,793)
Treasury stock	(1,391)	(1,411)
Total stockholders' equity	308,180	290,162
Total liabilities and stockholders' equity	$ 1,610,890	$ 1,615,025