Condensed Consolidating Financial Information - Balance Sheets (Details) - USD ($) $ in Thousands	Dec. 31, 2016	Sep. 30, 2016	Dec. 31, 2015	Sep. 30, 2015
Current assets:
Cash and cash equivalents	$ 70,858	$ 65,298	$ 115,636	$ 142,597
Trade receivables, net	118,272	152,084
Inventories	80,466	72,668
Current income taxes	1,905	1,187
Other	12,824	13,517
Total current assets	284,325	304,754
Property, plant and equipment, net	212,639	206,792
Other assets:
Goodwill	296,207	290,503
Intangible assets, net	309,614	319,162
Deferred income taxes	69,367	68,059
Other	48,043	49,173
Total other assets	723,231	726,897
Total assets	1,220,195	1,238,443	1,238,443
Current liabilities:
Accounts payable	25,992	30,211
Accrued personnel costs	31,448	45,366
Other accrued liabilities	61,621	63,785
Current portion of long-term debt		7,785
Total current liabilities	119,061	147,147
Long-term liabilities:
Long-term debt, net	740,402	746,716
Other	44,514	41,230
Total long-term liabilities	784,916	787,946
Total liabilities	903,977	935,093
Redeemable non-controlling interest in consolidated subsidiary	13,524	13,363
Stockholders' equity:
Common stock	75	74
Capital in excess of par value	739,156	733,117
Retained earnings (accumulated deficit)	(435,126)	(441,793)
Treasury stock	(1,411)	(1,411)
Total stockholders' equity	302,694	289,987
Total liabilities and stockholders' equity	1,220,195	1,238,443
Consolidation, Eliminations
Current assets:
Current income taxes	(58,566)	(58,802)
Total current assets	(58,566)	(58,802)
Other assets:
Investments in subsidiaries	(739,326)	(721,760)
Intercompany accounts and notes	(718,844)	(727,747)
Deferred income taxes	(11,929)	(12,077)
Total other assets	(1,470,099)	(1,461,584)
Total assets	(1,528,665)	(1,520,386)
Current liabilities:
Current income taxes	(58,566)	(58,802)
Total current liabilities	(58,566)	(58,802)
Long-term liabilities:
Deferred income taxes		(12,077)
Intercompany accounts and notes	(718,844)	(727,747)
Other	(11,929)
Total long-term liabilities	(730,773)	(739,824)
Total liabilities	(789,339)	(798,626)
Stockholders' equity:
Capital in excess of par value	(764,360)	(764,359)
Retained earnings (accumulated deficit)	25,034	42,599
Total stockholders' equity	(739,326)	(721,760)
Total liabilities and stockholders' equity	(1,528,665)	(1,520,386)
Guarantor Subsidiaries
Current assets:
Cash and cash equivalents	27,568	27,012	28,363	25,819
Trade receivables, net	111,306	145,443
Inventories	75,253	67,549
Other	11,924	11,975
Total current assets	226,051	251,979
Property, plant and equipment, net	194,299	179,758
Other assets:
Goodwill	252,553	248,016
Intangible assets, net	273,594	282,239
Intercompany accounts and notes	51,464	26,707
Other	12,155	13,293
Total other assets	589,766	570,255
Total assets	1,010,116	1,001,992
Current liabilities:
Accounts payable	24,205	27,659
Accrued personnel costs	10,598	14,945
Current income taxes	56,164	56,553
Other accrued liabilities	54,077	55,942
Total current liabilities	145,044	155,099
Long-term liabilities:
Deferred income taxes		12,077
Other	17,512	4,581
Total long-term liabilities	17,512	16,658
Total liabilities	162,556	171,757
Stockholders' equity:
Capital in excess of par value	711,756	711,755
Retained earnings (accumulated deficit)	135,804	118,480
Total stockholders' equity	847,560	830,235
Total liabilities and stockholders' equity	1,010,116	1,001,992
Non-Guarantor Subsidiaries
Current assets:
Cash and cash equivalents	7,661	5,304	3,715	3,577
Trade receivables, net	6,966	6,641
Inventories	5,213	5,119
Other	491	1,481
Total current assets	20,331	18,545
Property, plant and equipment, net	9,743	9,852
Other assets:
Goodwill	43,654	42,487
Intangible assets, net	36,020	36,923
Deferred income taxes	22,993	23,083
Other	10,982	10,922
Total other assets	113,649	113,415
Total assets	143,723	141,812
Current liabilities:
Accounts payable	1,119	1,301
Accrued personnel costs	472	519
Current income taxes	2,402	2,249
Other accrued liabilities	4,916	5,002
Total current liabilities	8,909	9,071
Long-term liabilities:
Intercompany accounts and notes	212,135	211,087
Other	17,564	16,941
Total long-term liabilities	229,699	228,028
Total liabilities	238,608	237,099
Redeemable non-controlling interest in consolidated subsidiary	13,524	13,363
Stockholders' equity:
Capital in excess of par value	52,429	52,429
Retained earnings (accumulated deficit)	(160,838)	(161,079)
Total stockholders' equity	(108,409)	(108,650)
Total liabilities and stockholders' equity	143,723	141,812
Parent
Current assets:
Cash and cash equivalents	35,629	32,982	$ 83,558	$ 113,201
Current income taxes	60,471	59,989
Other	409	61
Total current assets	96,509	93,032
Property, plant and equipment, net	8,597	17,182
Other assets:
Investments in subsidiaries	739,326	721,760
Intercompany accounts and notes	667,380	701,040
Deferred income taxes	58,303	57,053
Other	24,906	24,958
Total other assets	1,489,915	1,504,811
Total assets	1,595,021	1,615,025
Current liabilities:
Accounts payable	668	1,251
Accrued personnel costs	20,378	29,902
Other accrued liabilities	2,628	2,841
Current portion of long-term debt		7,785
Total current liabilities	23,674	41,779
Long-term liabilities:
Long-term debt, net	740,402	746,716
Intercompany accounts and notes	506,709	516,660
Other	21,367	19,708
Total long-term liabilities	1,268,478	1,283,084
Total liabilities	1,292,152	1,324,863
Stockholders' equity:
Common stock	75	74
Capital in excess of par value	739,331	733,292
Retained earnings (accumulated deficit)	(435,126)	(441,793)
Treasury stock	(1,411)	(1,411)
Total stockholders' equity	302,869	290,162
Total liabilities and stockholders' equity	$ 1,595,021	$ 1,615,025