Segment Information (Details) - USD ($) $ in Thousands		3 Months Ended		9 Months Ended
		May 31, 2017	May 31, 2016	May 31, 2017	May 31, 2016
Segment Reporting Information [Line Items]
Net sales to unaffiliated customers		$ 645,795	$ 650,439	$ 1,814,473	$ 1,891,419
Total gross profit		98,427	109,474	288,628	304,227
Operating income (loss)		32,222	31,588	72,659	73,740
Interest expense		(13,179)	(13,557)	(39,450)	(40,965)
Foreign currency transaction gains (losses)		68	(392)	(1,575)	(2,071)
Other income (expense), net		682	311	1,138	529
Income (loss) before taxes		19,793	17,950	32,772	31,233
Restructuring Related Costs		$ 2,000	$ 5,300	$ 8,800	$ 12,000
Net sales, percentage		100.00%	100.00%	100.00%	100.00%
Segment Reconciling Items [Member]
Segment Reporting Information [Line Items]
Accelerated depreciation and restructuring related costs		$ (236)	$ (2,930)	$ (2,101)	$ (7,311)
Costs related to acquisitions and integrations in gross profit		0	(423)	(57)	(2,522)
Lucent costs in gross profit	[1]	(104)	(466)	(190)	(1,844)
Costs related to acquisitions and integrations in operating income		0	(1,443)	(605)	(7,570)
Restructuring and related costs		(2,932)	(9,520)	(21,176)	(19,959)
Accelerated depreciation		(237)	(1,286)	(1,060)	(4,796)
Lucent costs in operating income	[1]	(1,730)	(1,951)	(3,135)	(6,268)
Asset impairment		0	0	(678)	0
CEO transition costs		0	0	(196)	0
Operating Segments [Member]
Segment Reporting Information [Line Items]
Total segment gross profit		98,767	113,293	290,976	315,904
Operating income (loss)		44,394	53,277	124,660	135,994
Corporate, Non-Segment [Member]
Segment Reporting Information [Line Items]
Corporate		(7,273)	(7,489)	(25,151)	(23,661)
EC [Member]
Segment Reporting Information [Line Items]
Net sales to unaffiliated customers		$ 59,252	$ 54,476	$ 165,091	$ 153,815
Net sales, percentage		9.00%	8.00%	9.00%	8.00%
Custom Concentrates and Services [Member]
Segment Reporting Information [Line Items]
Net sales to unaffiliated customers		$ 296,917	$ 300,391	$ 832,424	$ 864,685
Net sales, percentage		46.00%	47.00%	46.00%	46.00%
Performance Materials [Member]
Segment Reporting Information [Line Items]
Net sales to unaffiliated customers		$ 289,626	$ 295,572	$ 816,958	$ 872,919
Net sales, percentage		45.00%	45.00%	45.00%	46.00%
EMEA Segment [Member] | Operating Segments [Member]
Segment Reporting Information [Line Items]
Net sales to unaffiliated customers		$ 318,026	$ 322,368	$ 891,000	$ 940,794
Total segment gross profit		42,509	49,852	126,297	136,489
Total segment operating income		19,712	23,382	56,006	59,147
USCAN Segment [Member] | Operating Segments [Member]
Segment Reporting Information [Line Items]
Net sales to unaffiliated customers		167,881	183,338	476,217	532,437
Total segment gross profit		21,844	32,560	66,420	90,095
Total segment operating income		6,474	15,576	20,416	38,166
LATAM Segment [Member] | Operating Segments [Member]
Segment Reporting Information [Line Items]
Net sales to unaffiliated customers		47,408	43,377	129,286	126,738
Total segment gross profit		9,928	9,055	28,940	27,226
Total segment operating income		6,189	4,748	17,083	14,581
APAC [Member] | Operating Segments [Member]
Segment Reporting Information [Line Items]
Net sales to unaffiliated customers		53,228	46,880	152,879	137,635
Total segment gross profit		9,155	8,080	27,189	24,153
Total segment operating income		5,260	4,540	15,174	13,517
EC [Member] | Operating Segments [Member]
Segment Reporting Information [Line Items]
Total segment gross profit		15,331	13,746	42,130	37,941
Total segment operating income		$ 6,759	$ 5,031	$ 15,981	$ 10,583

[1] (1) Refer to Note 13, Commitments and Contingencies, for additional discussion on this matter. Lucent costs in cost of sales include additional product and manufacturing operational costs for reworking inventory. Lucent costs in selling, general and administrative expenses include legal and investigative costs. In addition, in the three and nine months ended May 31, 2016, Lucent costs in SG&A also include dedicated internal personnel costs that would have otherwise been focused on normal operations.