Condensed Consolidating Financial Information - Schedule of Unaudited Condensed Consolidating Statements of Operations and Comprehensive Income (Loss) (Details) - USD ($) $ in Millions	3 Months Ended				6 Months Ended		9 Months Ended
	May. 31, 2015	Aug. 31, 2014	May. 31, 2014	Feb. 28, 2014	May. 31, 2015	May. 31, 2014	Aug. 31, 2014
Condensed Income Statements, Captions [Line Items]
Net sales	$ 456.9	$ 421.2	$ 404.5	$ 332.1	$ 775.5	$ 736.6
Cost of sales (exclusive of items shown separately below)	372.5	376.5	369.4	288.5	655.3	657.9
Selling, general and administrative	12.6	9.7	9.2	9.2	28.1	18.4
Depreciation and amortization	16.1	15.8	15.7	14.9	32.1	30.6	$ 46.4
Interest expense	13.2		12.6		26.6	25.0
Other, net	2.8		48.3		4.4	55.9
Income (loss) from continuing operations before income taxes	39.7	(11.1)	(50.7)	(0.5)	29.0	(51.2)
Income tax provision (benefit)	21.3		(0.6)		14.7	1.2
Income (loss) from continuing operations	18.4	(10.1)	(50.1)	(2.3)	14.3	(52.4)
(Loss) income from discontinued operations, net of income taxes	0.0	0.2	(0.8)	0.0	0.2	(0.8)	(0.6)
(Loss) income before equity income of subsidiaries	18.4		(50.9)		14.5	(53.2)
Equity income of subsidiaries	0.0		0.0		0.0	0.0
Net income (loss)	18.4	$ (9.9)	(50.9)	$ (2.3)	14.5	(53.2)	$ (63.1)
Comprehensive income (loss)	30.6		(43.2)		38.9	(38.0)
Eliminations [Member]
Condensed Income Statements, Captions [Line Items]
Net sales	0.0		0.0		0.0	0.0
Cost of sales (exclusive of items shown separately below)	(0.2)		(0.1)		(0.3)	(0.3)
Selling, general and administrative	0.0		0.0		0.0	0.0
Depreciation and amortization	0.0		0.0		0.0	0.0
Interest expense	0.0		0.0		0.0	0.0
Other, net	0.2		0.1		0.3	0.3
Income (loss) from continuing operations before income taxes	0.0		0.0		0.0	0.0
Income tax provision (benefit)	0.0		0.0		0.0	0.0
Income (loss) from continuing operations			0.0		0.0	0.0
(Loss) income from discontinued operations, net of income taxes			0.0		0.0	0.0
(Loss) income before equity income of subsidiaries	0.0		0.0		0.0	0.0
Equity income of subsidiaries	(36.1)		(4.9)		(46.9)	(16.6)
Net income (loss)	(36.1)		(4.9)		(46.9)	(16.6)
Comprehensive income (loss)	(45.2)		(10.1)		(65.1)	(26.9)
Parent [Member]
Condensed Income Statements, Captions [Line Items]
Net sales	0.0		0.0		0.0	0.0
Cost of sales (exclusive of items shown separately below)	0.0		0.0		0.0	0.0
Selling, general and administrative	5.4		3.4		14.6	5.6
Depreciation and amortization	0.0		0.1		0.0	0.1
Interest expense	12.7		11.9		25.6	23.6
Other, net	6.4		44.6		8.4	49.5
Income (loss) from continuing operations before income taxes	(24.5)		(60.0)		(48.6)	(78.8)
Income tax provision (benefit)	(6.8)		(5.0)		(16.0)	(9.8)
Income (loss) from continuing operations			(55.0)		(32.6)	(69.0)
(Loss) income from discontinued operations, net of income taxes			(0.8)		0.2	(0.8)
(Loss) income before equity income of subsidiaries	(17.7)		(55.8)		(32.4)	(69.8)
Equity income of subsidiaries	36.1		4.9		46.9	16.6
Net income (loss)	18.4		(50.9)		14.5	(53.2)
Comprehensive income (loss)	30.6		(43.2)		38.9	(38.0)
Guarantor Subsidiaries [Member]
Condensed Income Statements, Captions [Line Items]
Net sales	442.2		397.7		755.5	723.2
Cost of sales (exclusive of items shown separately below)	363.9		362.3		643.0	645.3
Selling, general and administrative	6.7		5.5		12.5	12.0
Depreciation and amortization	15.9		15.3		31.6	30.0
Interest expense	0.5		0.7		1.0	1.4
Other, net	(3.2)		4.0		(3.0)	7.2
Income (loss) from continuing operations before income taxes	58.4		9.9		70.4	27.3
Income tax provision (benefit)	24.5		4.7		26.9	10.9
Income (loss) from continuing operations			5.2		43.5	16.4
(Loss) income from discontinued operations, net of income taxes			0.0		0.0	0.0
(Loss) income before equity income of subsidiaries	33.9		5.2		$ 43.5	16.4
Equity income of subsidiaries	0.0		0.0			0.0
Net income (loss)	33.9		5.2		$ 43.5	16.4
Comprehensive income (loss)	43.0		10.4		61.7	26.7
Non-guarantor Subsidiaries [Member]
Condensed Income Statements, Captions [Line Items]
Net sales	14.7		6.8		20.0	13.4
Cost of sales (exclusive of items shown separately below)	8.8		7.2		12.6	12.9
Selling, general and administrative	0.5		0.3		1.0	0.8
Depreciation and amortization	0.2		0.3		0.5	0.5
Interest expense	0.0		0.0		0.0	0.0
Other, net	(0.6)		(0.4)		(1.3)	(1.1)
Income (loss) from continuing operations before income taxes	5.8		(0.6)		7.2	0.3
Income tax provision (benefit)	3.6		(0.3)		3.8	0.1
Income (loss) from continuing operations			(0.3)		3.4	0.2
(Loss) income from discontinued operations, net of income taxes			0.0		0.0	0.0
(Loss) income before equity income of subsidiaries	2.2		(0.3)		$ 3.4	0.2
Equity income of subsidiaries	0.0		0.0			0.0
Net income (loss)	2.2		(0.3)		$ 3.4	0.2
Comprehensive income (loss)	$ 2.2		$ (0.3)		$ 3.4	$ 0.2